domain: sdv info

text:
Umar Faruk Murtala

Isabelle Bouvarel

Nathalie Même

Roffidal Lucien

Tukur ; Hussaini

Yves Nys

Dr Philippe Lescoat
email: lescoat@tours.inra.fr

Faruk

Usman

Adaptation of wheat and protein-mineral concentrate intakes by individual hens fed ad libitum in sequential or in loose-mix systems

Keywords: sequential feeding, loose-mix feeding, Feed intake, whole-wheat, Laying hen Treatment effect: p< 0.01 Time x Treatment: p<0.01 Anova repeated measures Treatment effect: p< 0.01 Time x Treatment: p<0.01 Anova repeated measures Treatment effect: p< 0.01

The use of whole cereal grain in poultry feeding is a popular practice in Northern Europe. The 65 reason has been the economic benefit as well as the local availability of these feedstuffs. In 66 countries where the cost of feed mixing hinders production, direct incorporation of cereal 67 grains could be an alternative. Although the benefits depend on the relative price of cereals, it 68 is important to have a clear knowledge of the impact of incorporating cereal grains in poultry 69 feeds on bird performance. Different methods such as choice feeding, loose-mix feeding and 70 sequential feeding can be used to offer cereal grains to poultry (Noirot et al., 1998). Choice 71 feeding is the simultaneous feeding of grains and a protein-mineral concentrate placed in 72 different containers. Loose-mix feeding is the distribution of these dietary components in a 73 single container. Sequential feeding involves the distribution of the two dietary components 74 separately at different times of the day. Choice feeding using cereal grains is accompanied by 75 an improvement in feed utilisation because it allows a degree of feed selection by the animal 76 [START_REF] Forbes | Application of diet selection by poultry with 397 particular reference to whole cereals[END_REF]Noirot et al., 1998). It has, however, the inconvenience of 77 requiring more than one feed trough to offer the different diets. Loose-mix and sequential 78 feeding, however, could be practical alternatives since only one trough is required. 79

Studies evaluating sequential and loose-mix feeding in laying hen are limited. Loose-80 mix feeding of laying hens was reported to reduce both feed and protein intakes when a 81 mixture of whole wheat, whole barley, kibbled maize and pellet protein concentrate was 82 offered [START_REF] Blair | Egg production responses of hens 388 given a complete mash or unground grain together with concentrate pellets[END_REF], or when fed on a (50:50) mixture of high energy/protein Ca diets 83 [START_REF] Lee | Effects of nutrient levels and feeding regimen of a.m. and 416 p.m. on laying hen performances and feed cost[END_REF]. Although the former observed similar egg production and egg weight to 84 conventional feeding, the latter reported a decrease in egg weight, which was related to a 85 decrease in energy intake. Loose-mix feeding of 60% barley and a protein concentrate was 86 reported to increase feed, energy and protein intakes, but to reduce egg production while 87 increasing egg weight [START_REF] Bennet | Performance of two strains of laying hens fed 385 ground and whole barley with and without access to insoluble grit[END_REF]. However, when the quantity of whole 88 4 wheat in a loose-mix diet was limited to 20%, similar intakes and egg production were 89 observed [START_REF] Kermanshashi | Feeding whole wheat with or without a 407 dietary enzyme or grit to laying hens[END_REF][START_REF] Macisaac | Effect of whole wheat, enzyme 421 supplementation and grain texture on the production performance of laying hens[END_REF]. 90 Sequential feeding of a mixture of whole cereals followed by a pelleted protein 91 concentrate resulted in increased feed and protein intakes while maintaining similar energy 92 intake, egg production and egg weight compared to a control diet [START_REF] Blair | Egg production responses of hens 388 given a complete mash or unground grain together with concentrate pellets[END_REF]. 93 Nevertheless, sequential feeding was reported to reduce feed, energy and protein intakes when 94 birds were fed on a protein concentrate in the morning followed by whole oats in the 95 afternoon [START_REF] Robinson | Performance of laying hens as affected by split time and split time 443 composition dietary regimens using ground and unground cereals[END_REF], or when fed on high-energy diet in the morning and protein 96 concentrate in the afternoon [START_REF] Leeson | Voluntary food restriction by laying hens mediated 419 through dietary self selection[END_REF][START_REF] Reichmann | The effects of meal feeding of calcium, 440 protein and energy on production and calcium status of laying hens[END_REF]Lee 97 and Ohh, 2002). Except for the work of [START_REF] Blair | Egg production responses of hens 388 given a complete mash or unground grain together with concentrate pellets[END_REF], all the other studies have reported 98 that sequential feeding results in lower egg production and egg weights. 99

Recent investigations on the sequential and loose-mix feeding of whole wheat and a 100 protein-mineral concentrate in laying hen revealed that sequential feeding was more efficient 101 compared to loose-mix and the conventional feeding of a complete diet (Umar Faruk et al., 102 2010). However, it was possible that this increased efficiency was linked to the experimental 103 protocol used. Feed intake was controlled by feeding a limited quantity (121 g/bird/d) of a 104 diet that contained 60.5 g each of whole wheat and concentrate. Birds were kept in groups and 105 this can facilitate social interactions among individuals and modify the birds' feeding patterns 106 through imitation [START_REF] Meunier-Salaün | On the feeding and social behaviour of 424 the laying hen[END_REF]. This management system also prevents 107 the study of individual responses to sequential and loose-mix feeding, since only the average 108 cage values could be measured. 109

The objective of the present experiment was to investigate the impact of sequential and 110 loose-mix feeding of birds kept in individual cages and given the diets ad libitum. 111 Furthermore, the study investigated the ability of birds under these feeding systems to adapt 112 their feed intake according to their requirements. 113

Pre-experimental period (weeks 16 -18) 115

A total of 149 ISA Brown layer hens were trained [START_REF] Forbes | Application of diet selection by poultry with 397 particular reference to whole cereals[END_REF] from week 16 116 to 18 to get them habituated to the feeding systems studied. The specific objective was to 117 adapt the sequentially-fed birds to whole-wheat intakes before they reached point of lay 118 [START_REF] Umar Faruk | Loose-450 mix and sequential feeding of mash diets with whole-wheat: effect on feed intake in laying 451 hens[END_REF]. The animals were housed in a three-tier battery having individual 119 cages (25 x 38cm). Each cage was equipped with a feed trough (20 cm per hen) and a nipple 120 drinker. A complete diet, named 'control habituation' (Table 1) and containing 160 g CP /kg 121 and 11.7 MJ/kg, was fed to a group of 33 birds as control (CH). Another diet, named 'balancer 122 diet habituation' and containing 180 g CP /kg and 11.0 MJ/kg, was fed sequentially (SH) with 123 wheat (13.0 MJ/kg) to another group containing 58 birds. Hens in this group were given 124 access to whole wheat (Triticum aestivum) in the morning and to the balancer diet in the 125 afternoon. The same diet, 'balancer diet habituation', was mixed with whole wheat and fed in a 126 loose-mix (LH) to another group containing 58 birds. The 'balancer diet habituation' was 127 formulated on the assumption that if the birds consumed 65% of it and 35% whole wheat, 128 they would ingest an equal amount of nutrients as those receiving diet CH. 129

Birds were fed ad libitum in line with the breeders' guidelines (ISA Hendrix Genetics, 130 2007). The total quantity of diet offered was progressively increased to account for the 131 increase in feed intake of a growing bird; it was increased from 70 g/bird/d in week 16 to 83 132 g/bird/d in week 18. In sequential feeding, the duration for which birds were given access to 133 wheat was increased in equal amounts from 3 h/d (week 16) to 7 h/d (week 18). were housed in the same house and kept in the individual cages that were used during the 141 habituation period. Body weight (BW) was used as criterion for the placement of the birds so 142 as to obtain a similar intra treatment BW. However, due to limited number of birds habituated 143 and the random choice of birds dissected for the measurement of the digestive organs, initial 144 BW for the treatment L50 was lower than C, S50 or S25. Photoperiod was 16 h and 145 temperature was maintained at 20.6±1.8°C throughout the experimental period. 146 A complete diet (Table1) containing 175 g CP /kg and 11.5 MJ/kg was fed ad libitum 147 as the control treatment (C). To investigate the ability of laying hens to adapt their intake 148 according to their energy and protein requirements, the balancer diet B50 (232 g CP /kg, 10.0 149 MJ/kg) was formulated to provide a similar nutritive value to C and assuming that the birds 150 would ingest equal quantities (50:50) of the diet and whole wheat. This diet was fed to two 151 experimental groups either sequentially (S50) or as a loose-mix (L50). Another balancer diet 152 B25 (195 g CP /kg, 11.0 MJ/kg) was formulated to provide similar nutritive values as C and 153 assuming that the birds would ingest it on a 75:25 basis with wheat. It was fed to the other 154 two groups either sequentially (S25) or in loose-mix (L25). Diets were fed ad libitum 155 containing equal amount of each of the fractions (wheat/protein mineral concentrate). Birds 156 fed on the B50 diet were expected to have a 50% wheat intake, while only 25% wheat intake 157 was expected for those fed on the B25 diet. Calcium carbonate (Ca) was ground and 158 incorporated in the balancer diet since the separate provision of granular Ca is not a 159 prerequisite when birds are fed on nutrient-fractioned diets (Balnave and Muritasari, 1990) Feed intake was measured weekly. In the two S fed treatments, wheat and balancer diet 162 intakes were determined separately. During the experimental period, wheat intake in L was 163 measured after manual separation using a sieve (2 mm Ф). 164

Eggs were collected daily and weighed individually. The weight of egg components 165 (yolk, albumen and shell) was determined on a daily sample every 4 weeks, starting at week 166 21. The albumen and the chalazae were separated using forceps prior to weighing the yolk. 167

The shells were washed and dried for 12 h in a drying oven at 70°C and then weighed. 168

Birds were weighed individually at 16, 19, 26 and 37 weeks of age. The weight of the 169 digestive organs was recorded at the end of the pre-experimental (week 19) and experimental 170 (week 42) periods to assess the effect of the feeding system on these organs. The birds were 171 weighed before being injected with sodium pentobarbital solution (1ml/kg body weight). The 172 abdominal cavity was opened and the digestive tract dissected and separated into 173 proventriculus, gizzard, duodenum, pancreas, jejunum and ileum. The segments were first 174 emptied and dried using a paper towel before weighing. The proventriculus and the gizzard 175 were placed in an ice container (-4°C) for 3 h to facilitate the removal of the surrounding fat. 176

The organs were emptied prior to weighing. 177

Metabolisable energy (kJ/b/d) and protein (g/b/d) intakes were estimated as a product 178 of feed intake and ME and protein contents of the experimental diets respectively. ME 179 requirement was estimated according to [START_REF] Sakomura | Modelling energy utilization in broiler breeders, laying hens and 446 broilers[END_REF] 180

ME (kJ/b/d) = W 0.

Statistical analysis 188

Individual values from cages were analysed using StatView (version 5, SAS Institute Inc., 189 Cary, NC). A one-way ANOVA was performed using the GLM model to test the treatment 190 effect on feed intake, egg production, egg weight, body weight, digestive organs weight, ME 191 intake and requirements. A 2x2 factorial ANOVA was carried out to test the effect of feeding 192 system (loose-mix vs sequential) and balancer diet effect (50 vs 25). Results were considered 193 significantly different if P <0.05 and Bonferroni-Dunnet pairwise comparison was used to 194 compare differences between means. Repeated measures ANOVA was performed on BW, 195 feed and wheat intakes, and egg mass to test the effect of treatment over time. 196 RESULTS 197 During the habituation period, no differences in total feed intakes were observed between the 198 treatments (62.4, 62.5 and 62.4 ± 0.3 g/bird/d for CH, LH and SH respectively). The wheat 199 intakes of the birds given the SH treatment increased from 13.0 to 40.0 g/bird/d from week 16 200 to 18 respectively. Their balancer-diet intake, however, decreased with increasing age and 201 wheat intake from 51.6 g/bird/d in week 16 to 40.0 g/bird/d in week 18. This increase in 202 wheat intake with the resulting decrease in balancer diet intake during this period suggested a 203 successful adaptation to wheat intake for SH-fed birds. There were no differences in BWG 204 between week 16 and week 18 (8.1, 8.3, and 8.6 ± 0.1 g/bird/d for CH, LH and SH 205 respectively). 206

During the experimental period, the mean total feed intake was lower for birds given 207 the treatment L25 than C, S50 and S25, although it was similar to L50 (Table 2). and L50 had lower feed intakes from week 30 of age but with a higher weekly variability than 211 the other three treatments. Wheat intake was higher for birds given L50, L25, S50 and S25 212 (Table 2). There was a progressive but significant decrease in wheat intake over time, 213 especially with treatments S25 and S50 (Figure c). 214

Egg production and egg weight were reduced with L25 compared with S50 and S25 215 (Table 2). Egg production and weight were, however, not statistically different between L25, 216 shows that the birds which received L50 had a similar growth rate to the other treatments. 227 Conversely, L25, which was similar in BW to all treatments at the beginning of the 228 experiment, had reduced growth, thus having a lower BW than C, S50 and S25 at the end of 229 the experiment. 230

Feeding system affected the birds' feed intakes and egg-laying performance and the 231 birds fed sequentially had higher total feed intakes than those fed on the loose-mix (Table 2). 232

The latter had higher wheat intakes. Hens fed sequentially had higher egg numbers, egg 233 weight and albumen weight than those fed on the loose-mix. BW was higher in the birds fed 234 Birds receiving balancer diet optimised for 25% wheat intake had lower mean total 237 feed and wheat intakes compared with those receiving diet optimised for 50% (Table 2). Egg 238 numbers, egg weight, egg albumen weight, FCR and final BW were similar for these two 239 diets. However, BWG was higher in the birds fed on balancer diet optimised for 50% wheat 240 intake compared with that optimised for 25%. 241

There was a similar ME intake for all treatment groups (Table 3). Estimated ME 242 requirement for treatment L25 was lower than that of C, S50 and S25 but similar to L50. The 243 difference between ME intake and ME requirement was higher for birds fed on L25 than S50, 244 S25 or C, although it was similar to L50, indicating a surplus in ME intake of birds in these 245 treatment groups. Protein intake was reduced with L25-fed birds compared with the other 4 246 treatments. Protein intake of birds fed on L50 was lower than C and S50 but similar to S25. 247

The estimated protein requirement was reduced in birds fed on L25 compared with C, S50 248 and S25 but similar to L50. The difference between protein intake and requirement was small 249 for birds fed on L25 and S25 compared with those fed on S50. 250 ME intake was similar for the sequential and loose-mix systems (Table 3). Estimated 251 ME requirement of sequentially fed birds was significantly higher than the loose-mix group. 252

The difference between ME intake and estimated requirement was lower for birds fed 253 sequentially. Both intake and estimated requirement of protein were significantly higher in 254 birds fed sequentially than in those fed on loose-mix. 255 ME intake and estimated requirements and the differences between ME intake and 256 estimated requirement were similar between the two balancer diets (Table 3). Protein intake 257 was low for birds receiving the balancer diet formulated for 25% wheat intake relative to 258 At the end of habituation period (week 19), similar relative weights of proventriculus, 261 liver and pancreas were observed between CH, SH and LH (Table 4). The relative weight of 262 the duodenum was lower for birds in the LH group than SH. The relative weight of the ileum 263 was heavier for birds in SH group than with those in LH and CH. There were significant 264 differences in gizzard and jejunum weights between the treatment groups, but the differences 265 were not proven using the Bonferroni-Dunnet pairwise comparison test due, probably because 266 of the limited number of birds killed (8/treatment). 267

At the end of the experimental period (week 42), the proventriculus was heavier in the 268 birds given S than the C and L treatments; the gizzard was heavier for the S and L treatments 269 compared with C; the duodenum was heavier for S compared with C; the liver was heavier 270 with the L treatment compared with C and the pancreas was heavier for S and L treatments 271 compared with C. There were no significant differences in the weights of the jejunum and 272 ileum between the three treatments. 273 DISCUSSION 274

None of the 4 treatments receiving whole wheat had a daily wheat intake that met the 275 expected 25 or 50% of the total daily feed intake. The birds receiving the diet formulated for 276 50% wheat intake consumed slightly less wheat (47%) than anticipated, whereas those fed on 277 the diet formulated for 25% wheat intake consumed more wheat (41%). However, no 278 treatment differences in ME intake were observed, which suggests that there was an 279 adjustment by the sequential and loose-mix fed birds to consume a similar ME to those fed on 280 the complete diet C. This lends support to work of [START_REF] Blair | Egg production responses of hens 388 given a complete mash or unground grain together with concentrate pellets[END_REF], Kermanshashi and 281 Classen (2001) and [START_REF] Macisaac | Effect of whole wheat, enzyme 421 supplementation and grain texture on the production performance of laying hens[END_REF], who reported similar ME intakes in birds 282 fed on a loose-mix or complete diet. However, in sequential feeding, Leeson and [START_REF] Reichmann | The effects of meal feeding of calcium, 440 protein and energy on production and calcium status of laying hens[END_REF], [START_REF] Robinson | Performance of laying hens as affected by split time and split time 443 composition dietary regimens using ground and unground cereals[END_REF], and [START_REF] Lee | Effects of nutrient levels and feeding regimen of a.m. and 416 p.m. on laying hen performances and feed cost[END_REF] reported a 284 decrease in ME intake, along with a reduced feed intake, which was not the case in the present 285 work. 286 Birds fed sequentially had higher feed intakes compared with the loose-mix treatment, 287 but this was not in accordance to our earlier work with birds housed in groups (Umar Faruk et 288 al., 2010), where a higher feed intake was obtained with loose-mix than with sequential 289 feeding. In this earlier work, the birds were housed in groups and fed on limited quantities of 290 the two dietary fractions. The lower feed intakes with loose-mix in the present experiment 291 was mainly attributed to treatment L25, because of its similar balancer diet intake compared 292 to L50. Although L25 fed birds consumed more wheat than expected, their balancer diet 293 intake remained similar to L50, thereby reducing their total intake. 294

The higher wheat intake when birds were fed with a loose-mix relative to those fed 295 sequentially agree with earlier observations under different conditions (Umar Faruk et al., 296 2010). Increased wheat intake has been associated with larger feed particle preference in 297 laying hens [START_REF] Picard | Picorage et 435 préhensibilité des particules alimentaires chez les volailles[END_REF][START_REF] Umar Faruk | Loose-450 mix and sequential feeding of mash diets with whole-wheat: effect on feed intake in laying 451 hens[END_REF]. [START_REF] Portella | Apparent feed particle size 438 preference in laying hens[END_REF] observed a 298 greater disappearance of larger particles when birds were fed on regular crumbles, and the 299 smaller particles disappeared only as the concentration of large ones decreased. In the present 300 work, the inclusion of whole wheat in the concentrate diet is likely to have increased the 301 heterogeneity of the diet, thus increasing selection of the larger particles (whole wheat) first. 302

Birds fed sequentially consumed more balancer diet than those fed on a loose-mix. 303 [START_REF] Blair | Egg production responses of hens 388 given a complete mash or unground grain together with concentrate pellets[END_REF] observed an increased feed intake when birds were fed sequentially and, in 304 particular, when there was a high intake of protein concentrate. However, sequential feeding 305 using an energy-rich diet in the morning and a protein concentrate in the afternoon (Leeson 306 and Summers, 1978;[START_REF] Reichmann | The effects of meal feeding of calcium, 440 protein and energy on production and calcium status of laying hens[END_REF]) reduced feed intake. Feed intake was also 307 reduced when oats/sorghum were sequentially fed with a protein concentrate (Robinson,308 . [START_REF] Lee | Effects of nutrient levels and feeding regimen of a.m. and 416 p.m. on laying hen performances and feed cost[END_REF] also reported a reduction in feed intake when birds were fed on a 309 high energy/protein and low Ca diet in the morning followed by a low energy/protein and 310 high Ca in the afternoon. In the present work, the high balancer diet intake with the sequential 311 feeding agreed with the feeding patterns observed with laying hens (Ballard and Biellier, 312 1969;[START_REF] Nys | Food, calcium and 433 water intakes by hens lit continuously from hatching[END_REF]Keshavarz, 1998a,b;[START_REF] Choi | Feed consumption pattern of laying hens 391 in relation to time of oviposition[END_REF]. Birds consume larger amount 313 of food in the afternoon partly in association with the hen Ca appetite which coincides with 314 the initiation of eggshell formation during this period. For example, Keshavarz (1998a) found 315 that hens subjected to a 16-h photoperiod consumed 40% of daily feed intake in the first 8 h 316 after light-on and 60% during the second 8 h period before light-off, with a marked increase 317 recorded 4 h before light-off (Keshavarz, 1998b). 318

The laying hen adapts its feed intake relatively well to the energy value of its feed, 319 although this regulation is not perfect [START_REF] Joly | Influence du niveau énergétique sur les performances de la 400 pondeuse à oeufs roux et évolution de l'ingérée en fonction de l'âge. 2ème Journées de la 401 recherches avicoles[END_REF], because the hen is influenced 320 by the form and method in which the feed is presented. Data in the present work were 321 subjected to a t-test to see if the ME intake minus ME requirement were different from zero. 322

Results showed that no difference between the ME intake and the ME requirements for the 323 birds in groups C as well as L50, suggesting that the two groups have adapted their ME intake 324 to their estimated requirements. However, birds fed on S50 and S25 had lower ME intakes 325 than the estimated requirements. L25 had a significantly higher intake than requirement, 326 although their efficiency of utilising this energy was apparently poor because they had the 327 lowest performance. Despite their lower-than-estimated ME intake, the birds fed on S50 and 328 S25 had similar egg-laying performance to those fed on the control diet. This was also 329 observed in previous work (Umar Faruk et al., 2010) and in the earlier work of Leeson and 330 Summers (1978) and [START_REF] Reichmann | The effects of meal feeding of calcium, 440 protein and energy on production and calcium status of laying hens[END_REF], who observed that sequential feeding 331 reduced the mean feed intake without reducing egg production, relative to the control. These 332 authors associated it to lower maintenance requirements due to the lower body weights in the 333 sequentially fed birds. In the present work, it may be due to an improvement in the rate of 334 utilisation of nutrients evidenced by a heavier gizzard, proventriculus and duodenum observed 335 with sequential than the loose-mix or control birds. 336

Loose-mix-fed birds laid fewer eggs and had a lower egg weight than those fed 337 sequentially. A reduction in protein intake is usually accompanied by a reduction in both egg 338 production and egg weight [START_REF] Morris | Partitioning of the response to protein between egg 426 numbers and egg weight[END_REF], and protein intakes were lower with 339 loose-mix treatment. Ad libitum access to the diets gave higher wheat consumption in the 340 loose-mix birds [START_REF] Umar Faruk | Loose-450 mix and sequential feeding of mash diets with whole-wheat: effect on feed intake in laying 451 hens[END_REF], which resulted in a low overall protein intake. 341

At the end of the experimental period, the sequential and loose-mix fed birds had 342 heavier gizzards than those receiving the control diet. This was to be expected because 343 feeding whole wheat grain increases the dietary particle size of the diets, and dietary particle 344 size is known to influence the avian digestive tract [START_REF] Nir | Effect of particle size of sorghum grains on 428 feed intake and performance of young broilers[END_REF]. This increase in gizzard 345 weight was hypothesised to contribute to the better performance of sequentially-fed, group-346 housed hens studied by Umar Faruk et al. (2010). In the present work, no improvement in 347 performance was observed; this was likely to be a consequence of the broad intra-treatment 348 variations and the ad libitum feeding. Changes in liver weight were in line with the findings of 349

De [START_REF] De Basilio | Early age thermal 394 conditioning and a dual feeding program for male broilers challenged by heat stress[END_REF], who found heavier livers in broilers that had been fed on cereal 350 grains. It was also in line with the observations of Umar Faruk et al. (2010), who observed 351 heavier liver weights in birds fed on whole wheat. 352

In conclusion, the present study confirmed our earlier report (Umar Faruk et al., 2010) 353 that sequential feeding has no adverse effect on egg production, thus outlining its potential as 354 a feed management method for egg producers. When birds are allowed ad libitum access to 355 concentrate diets formulated for different proportion of wheat intake, it is evident that they 356 will not always consume the expected proportion of the respective fractions. In sequential 357 feeding, similar feed intakes and egg-laying performance to the control group were obtained 358 irrespective of the concentrate diet used. This system could therefore be used to advantage in 359 situations where the cost of grinding and feed mixing hinders production. In loose-mix 360 feeding, distributing concentrated diets optimised for 25% wheat intake reduced nutrient 361 intake and performance as the hens failed to eat the appropriate proportion of the dietary 362 fractions, and so this management technique should be avoided. 363

The advantages of sequential feeding needs to be further explored in terms of the 364 physical form (whole, ground) and type of cereals (millet, sorghum, maize etc) to be used. Ad 365 libitum feeding in sequential feeding resulted in excessive intake of the concentrate diet and 366 this may increase cost and so requires additional investigation. Feeding management (van 367 Krimpen et al., 2005), especially sequential feeding (Jordan et al., 2009), induces feather 368 pecking in laying hens, due to a reduction in time spent on feeding activity. Therefore, the 369 optimal duration of the sequence (wheat-balancer diet) in sequential feeding needs to be 370 1 C = Control, S50 = Sequential feeding of diet formulated for 50% wheat, S25 = Sequential feeding of diet formulated for 25% wheat, L50 = Loose-470 mix feeding of diet formulated for 50% wheat, L25 = Loose-mix feeding of diet formulated for 25% wheat. 471 2 Results were not presented where interaction between feeding system and balancer diet effect were observed 472 a,b,c Values within the same column not sharing a common superscript differ significantly at P <0.05, NS = not significant at P >0.05. 473 474 Difference between requirement and intake were estimated as intake minus requirement.

481 5 C = Control, S50 = Sequential feeding of diet formulated for 50% wheat, S25 = Sequential feeding of diet formulated for 25% wheat, L50 = Loose-mix feeding of diet formulated for 482 50% wheat, L25 = Loose-mix feeding of diet formulated for 25% wheat. Result were not presented where interaction between feeding system and balancer diet effect were observed. No difference in organs weight between treatments of the same feeding system and no interaction (feeding system x balancer diet level) was observed. 490 Therefore, animals receiving diet 25 were put together with their corresponding 50 treatments to increase the population size from 16 to 24.

  75 *(165.74 -2.37*T) + 6.68*WG + 2.40*EM 181 where, ME = energy requirement (kJ/bird/d), W = Body weight (kg), T = Temperature (°C), 182 WG = weight gain (g/d), EM = Egg mass (g/bird/d). 183 Protein requirement was estimated according to Sakomura et al., (2002) 184 PB = 1.94*W .075 + 0.480*G + 0.301*EM 185 = protein requirement (g/bird/d), W = body weight (kg), G = daily weight gain 186 (g/d) and EM = egg mass (g/bird/d). 187

  Figure (b) 208shows the weekly change in feed intake according to treatment from 19 to 42 weeks. There 209 was a significant increase in feed intake in all treatments with time, although birds fed on L25 210

  L50 and C. Birds in treatment L25 had a significantly smaller egg mass and lower egg yolk 217 weight compared with the other 4 treatments. Egg mass in this treatment was progressively 218 reduced from week 23 and was generally low through out the experimental period (Figure d). 219 Eggshell weight was significantly reduced with L25 when compared with S25, S50 and L50. 220 There were no significant treatment differences for albumen weight. Feed conversion ratios 221 (FCR) were similar among all treatments. 222 BW at week 19 was significantly lower for birds receiving L50 than for C, S50 and 223 S25, although they were similar to L25 (Table 2); this was associated with the low BW of the 224 treatment group upon arrival at week 16 (Figure a). Although L50 was initially low in BW, 225 the final BW (week 42) was lower for L25 compared with C, S25 and S50. The Figure (a) 226

  those fed on loose-mix and this was associated with the higher initial 235 BW. FCR and BWG were similar for the two systems. 236

F

  (KJ/b/d) and protein (g/b/d) intakes were calculated as the product of feed intake and diet composition.

  (kJ/b/d) and protein (g/b/d) were estimated according to[START_REF] Sakomura | Modelling energy utilization in broiler breeders, laying hens and 446 broilers[END_REF] and[START_REF] Sakomura | Modelling 448 protein utilization in laying hens[END_REF] respectively. 480 4

F

  ,c Values within the same column not sharing a common superscript differ significantly at P <0.05, NS = not significant at P >0.05. 485

  491 2 CH= Control Habituation, SH= sequential habituation, LH= loose-mix habituation, C = Control, L = Loose-mix, S = Sequential 492 a,b,c: Values within the same row not sharing a common superscript differ significantly with Bonferroni-Dunnet (P <0.05), NS = not significant at P 493

of wheat and protein-mineral concentrate intakes by individual hens fed ad 2 libitum in sequential or in loose-mix systems.

	1 64	INTRODUCTION
	Adaptation 3
	4
	5	M. UMAR FARUK 3 , I. BOUVAREL 1 , N. MÊME, L. ROFFIDAL 2 ,
	6	H. M. TUKUR 3 , Y. NYS AND P. LESCOAT
	7
	F o r P e e r R e v i e w O n l y INRA, UR83 Recherches Avicoles, F-37380 Nouzilly, France, 1 Institut Technique de l'Aviculture (ITAVI), F-37380 Nouzilly, 2 INZO°, Montgermont, France and 3 Department of Animal Science, Usman Danfodio University Sokoto, Nigeria o r P e e r R e v i e w O n l 37 F 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 y
		1

Experimental period (weeks 19 -42) 137

	138	Five treatments were introduced at 19 weeks of age. Each of the sequential and loose-mix
	139	groups was divided into two groups to form 4 treatments of 25 birds each. The other 25 birds
	140	from the CH group formed the control treatment. During the experimental period, the birds
		F o r
		P
		e
		e r
		R
		e
		v i e	Table 1 near here
		w
		O n l
		y
	134		The
	135	photoperiod was 10 h at week 16 and reached 16 h at week 18. Water was given ad libitum
	136	throughout the study.
			6

  . 160

		F o r
		P
		e
		e r
		R
		e
		v i e
		w
		O n l
		y
	161	Measurements
		7

Table 2 and

 2 Figure near here

Table 3

 3

	near here

Table 1 .

 1 Composition of experimental diets 461 462

			Habituation Period (16-18 week)	Experimental Period (19-42 week)	Both periods
		Ingredient (g/kg )	Control habituation (CH)	Balancer diet habituation (LH)	Control (C)	Balancer diet Balancer diet B50 B25	Whole Wheat (Triticum aestivum)
		Wheat	346.6	-	500.0	-	-	100
		Maize	350.0	535.7	161.3	320.8	498.4
		Wheat bran	100.0	153.1	25.4	50.1	45.0
		Maize gluten	-	-	32.9	66.2	24.0
		Soya bean meal (T48)	165.0	252.5	169.7	340.8	285.0
		Soya bean oil	-	-	8.0	16.0	10.0
		Calcium carbonate	18.4	28.2	80.0	160.4	105.1
		Bi-calcium phosphate	10.9	16.7	11.6	23.3	17.4
		Refined sodium chloride	2.0	3.1	2.0	4.0	2.7
		Sodium bicarbonate	2.0	3.1	2.0	4.0	2.7
		L-Lysine 78	-	-	1.1	2.2	1.3
		DL-Methionine	0.1	0.2	1.1	2.2	1.8
		Premix (Sup 64 J 02) 1	5.0	7.7	5.0	10.0	6.7
		Calculated composition (g/kg as fed
		basis)
		Metabolisable energy (MJ/kg)	11.7	11.0	11.5	10.0	11.0	13.0
		CP	160.5	183.3	175.2	233.2	194.7	119.0
		DM	877.0	875.0	891.0	899.0	889.0	868.0
		Fibre	35.9	41.0	30.1	33.7	32.7	26.5
		Lysine	7.2	9.3	8.1	13.1	10.7	3.1
		Methionine	3.2	3.9	4.5	7.1	5.7	2.0
		Calcium	12.0	18.2	36.1	72.0	48.0	0.3
		Total P	5.6	7.1	5.3	7.6	6.4	3.0
		Analysed composition (g/kg)
		DM	890.0	887.0	888.0	895.0	890.0	867.0
		CP	157.0	186.0	173.0	230.0	195.0	119.0
	463	1 Vitamin and mineral premix supplied the following amounts per kg of premix: 1200 mg of Cu (sulphate), 4000 mg of Fe, 200 mg of I, 60 mg of Se, 120 g of DL-methionine, 200
	464	mg of canthaxanthine; 11000 mg of Zn, 12000 mg of Mn; retinol 480 mg, cholecalciferol 12 mg, DL ∝-tocopherol acetate 2000 mg, menadione 400 mg, thiamine mononitrate 109
	465	mg.

Table 2 .

 2 Effect of treatment, feeding system and balancer-diet composition on the feed intake and performance of hens fed whole wheat sequentially 466 (S) or in loose-mix (L) with a balancer diet formulated for either 50 or 25% wheat intake from 19 to 42 weeks of age 467 468

				Eggs
		Feed	Wheat	produced		Egg	FCE				Egg	Egg
		Intake	intake/Feed	per hen	Egg	mass	(g egg/ g	BW wk 19	BW wk	BWG	Yolk	Albumen	Eggshell
		(g/b/d)	intake	per d	weight (g)	(g/d)	feed)	(g)	42 (g) 2	(g/d)	(g)	(g)	(g)
	Treatments 1
	C	114.4 ab	-	0.946 ab	57.3 ab	54.2 a	0.473	1560 a	1832 a	1.7 a	14.2 a	36.9	6.0 ab
	S50	115.7 a	0.384 c	0.950 a	58.2 a	55.5 a	0.481	1588 a	1810 a	1.4 ab	14.0 a	38.0	6.1 a
	S25	111.5 ab	0.315 d	0.947 a	58.4 a	55.3 a	0.498	1603 a	1809 a	1.1 ab	14.1 a	38.0	6.3 a
	L50	107.0 bc	0.563 a	0.924 ab	57.2 ab	53.4 a	0.486	1485 b	1722 ab	1.4 ab	14.0 a	37.2	6.1 a
	L25	102.8 c	0.502 b	0.886 b	55.0 b	49.0 b	0.476	1545 ab	1622 b	0.6 b	13.2 b	35.4	5.7 b
	P value	<0.01	<0.01	<0.05	<0.05	<0.01	NS	<0.01	<0.05	<0.05	<0.05	NS	<0.05
	SEM	0.97	1.20	0.69	0.35	0.50	0.004	8.10	17.73	0.09	0.09	0.30	0.04
	Feeding system 2
	L	104.8 b	0.532 a	0.904 b	56.0 b	-	0.480	1515 b	1688 b	1.1	-	36.4 b	-
	S	113.7 a	0.350 b	0.948 a	58.3 a	-	0.490	1596 a	1810 a	1.3	-	38.0 a	-
	P value	<0.01	<0.01	<0.05	<0.05	-	NS	>0.01	<0.05	NS	-	<0.05	-
	SEM	1.11	1.20	0.83	0.40		0.005	9.52	20.23	0.09		0.34
	Balancer Diet effect
	50	111.3 a	0.474 a	0.937	57.8	-	0.483	1535 b	1766	1.4 a	-	37.7	-
	25	107.0 b	0.412 b	0.916	56.6	-	0.487	1573 a	1716	0.9 b	-	36.9	-
	P value	<0.05	<0.05	NS	NS	-	NS	<0.05	NS	<0.05	-	NS	-
	SEM	1.11	1.20	0.83	0.40		0.005	9.52	20.23	0.09		0.34
	Interaction
	FS x DC	NS	NS	NS	NS	<0.05	NS	NS	NS	NS	<0.05	NS	<0.05
	469

Table 3 .

 3 Effect of treatment, feeding system and balancer-diet composition on the feed, ME and protein intakes and ME and protein requirements of 475hens fed whole wheat sequentially (S) or in loose-mix (L) with a balancer diet formulated for either 50 or 25% intake of wheat from 19 to 37 weeks ofValues shown are averages from week 19 to 37 because body weight at week 42 was only measured for the birds used in the measurement of digestive organs.

	476
	477				age 1
			Wheat			Difference	Protein	Protein	Difference
		Feed intake	intake/Feed	ME intake	ME Requirement	ME	intake	Requirement	Protein
		(g/b/d)	intake	(kJ/b/d) 2	(kJ/b/d) 3	(kJ/b/d) 4	(g/b/d)	(g/b/d)	(g/b/d)
	Treatments 5
	C	113.1 a	-	1300.0	1321.4 a	-21.1 b	19.8 b	19.9 a	-0.1 ab
	S50	113.6 a	0.387 c	1264.2	1311.0 a	-47.0 b	21.4 a	20.1 a	1.3 a
	S25	109.9 a	0.320 d	1280.0	1308.1 a	-28.2 b	18.7 bc	20.0 a	-1.3 b
	L50	106.6 ab	0.569 a	1274.0	1241.0 ab	33.0 ab	18.4 c	18.5 ab	-0.1 ab
	L25	101.5 b	0.503 b	1226.0	1178.1 b	47.7 a	15.9 d	17.4 b	-1.5 b
	P	<0.01	<0.01	NS	<0.01	<0.05	<0.01	<0.01	<0.01
	SEM	1.00	1.17	9.20	10.30	9.00	0.23	0.23	0.22
	Feeding system 6
	L	103.9 b	0.533 a	1248.0	1207.0 b	41.0 a	17.1 b	18.0 b	-
	S	111.8 a	0.354 b	1272.0	1310.0 a	-37.7 b	20.1 a	20.0 a	-
	P	<0.05	<0.01	NS	<0.01	<0.01	<0.01	<0.01	-
	SEM	1.12	1.17	10.50	11.61	10.60	0.27	0.27
	Balancer Diet effect
	50	110.4 a	0.472 a	1269.0	1279.2	-11.0	20.0 a	19.4	-
	25	105.5 b	0.415 b	1252.3	1242.0	11.0	17.3 b	18.7	-
	P	<0.05	<0.05	NS	NS	NS	<0.01	NS	-
	SEM	1.12	1.17	10.50	11.61	10.60	0.27	0.27
	Interaction
	FS x DC	NS	NS	NS	NS	NS	NS	NS	<0.05
	1

Table 4 .

 4 Effect of feeding system on weight of digestive organs (g/kg body weight) at weeks 19 and 42 of birds fed whole wheat sequentially or in

	486
	487			loose-mix with a balancer diet
	488
			Week 19					Week 42 1
	Organ (g/kg)	Feeding system 2 CH (n=8) SH (n=8) (n=8) LH	P value	SEM	C (n=16)	Feeding system S (n=24) L (n=24)	P value	SEM (n=16)	SEM (n=24)
	Proventriculus	3.1	3.1	2.8	NS 0.08 3.3 b	3.7 a	3.3 b	<0.05 0.11	0.08
	Gizzard	18.5	21.9	21.7 <0.05 0.62 11.8 b	13.8 a	14.7 a <0.05 0.48	0.37
	Duodenum	5.4 ab	6.4 a	5.1 b <0.05 0.21 5.2 b	5.9 a	5.5 ab <0.05 0.20	0.18
	Jejunum	8.5	10.1	8.5	<0.05 0.30	9.4	9.5	9.7	NS	0.26	0.24
	Ileum	6.3 b	7.5 a	6.2 b <0.05 0.22	7.6	7.2	7.4	NS	0.25	0.19
	Liver	24.7	25.1	24.4	NS 0.74 25.5 b	26.8 ab	28.9 a <0.05 0.76	0.91
	Pancreas	2.1	2.2	2.2	NS 0.06 1.6 b	1.8 a	1.8 a	<0.05 0.06	0.06
	489
	1

E-mail: br.poultsci@bbsrc.ac.uk URL: http://mc.manuscriptcentral.com/cbps British Poultry Science

E-mail: br.poultsci@bbsrc.ac.uk URL: http://mc.manuscriptcentral.com/cbps

ACKNOWLEDGEMENTS 372

The authors acknowledge the technical assistance given by Jean-Marc Hallouis, Anne-Marie 373 Chagneau, Maryse Leconte and Serge Mallet. They also thank Lucille Delestre, Valentine 374

Froget and Amandine Soria for their help in data collection. The help of our experimental unit 375 (UE PEAT) in the set-up of this experiment was highly appreciated. Finally we thank France 376 AgriMer, CNPO and INZO° for their financial support. 377


Dr Jennifer Ann Howie
email: jhowie@aviagen.com

Bert J Tolkamp

Ilias Tobias ; Bley

I Kyriazakis

Short-term feeding behaviour has a similar structure in broilers, 1 turkeys and ducks 2

Keywords: Behaviour, Feed intake, Modelling, Turkeys, Ducks, Broilers

HAL is

Because of the importance of feed consumption in animal production systems, records of 50 visits to feeders are increasingly being collected to measure daily intake in animals such as 51 cattle (Tolkamp et al., 1998b), pigs (Morgan et al., 2000a) and poultry (Howie et al.,. 52 2009a). Such data sets have also formed the basis for analyses of short-term feeding 53 behaviour in each of these species [START_REF] Friggens | Effects of feed composition and stage of lactation on the short-term feeding 416 behavior of dairy cows[END_REF]Hall et al., 1999;Bley and Bessei 54 2008). It has been shown, however, that even small changes in feeder construction or software 55 settings can have large effects on daily number of visits, median visit duration and intake per 56 visit, without changing daily intake [START_REF] Tolkamp | The biologically 459 relevant unit for the analysis of short-term feeding behavior of dairy cows[END_REF]. It is, therefore, difficult to 57 quantitatively compare analyses of short-term feeding behaviour between studies, even if the 58 basic unit is measured in terms of visits to feeders in the same species. This is further 59 complicated if data are collected with species-specific feeders or by other techniques, such as 60 direct observation [START_REF] Bokkers | Eating behaviour and preprandial and 410 postprandial correlations in male broiler and layer chickens[END_REF] or recording pecks [START_REF] Machlis | An analysis of the temporal pattern of pecking in chicks[END_REF], that result 61 in different definitions of the basic unit in which feeding is expressed. 62

In many species, feeding behaviour is organised in bouts and these bouts, or meals, are 63 therefore considered a more biologically relevant unit for analyses of short-term feeding 64 behaviour [START_REF] Lemagnen | Hunger[END_REF][START_REF] Forbes | Voluntary food intake and diet selection in farm animals[END_REF]). The grouping of short feeding events, such as 65 visits to feeders or pecks, into meals would allow a comparison of feeding behaviour, even 66 when data are obtained with different techniques or different species. To do this, a meal 67 criterion needs to be estimated [START_REF] Slater | Minimizing errors in splitting behavior into bouts[END_REF][START_REF] Langton | Splitting Behavior Into Bouts -A 428 Maximum-Likelihood Approach[END_REF]. Because results 68 of meal pattern analysis can be greatly affected by the value of the meal criterion estimate 69 robust estimations of reliable meal criteria by previously developed methods (Howie et al., 74 2009a). The study also suggested that the underlying controls of food intake were unaffected 75 by intensive selection for production traits. For the current study we hypothesised that the 76 structure of short-term feeding behaviour of Pekin ducks and turkeys would be sufficiently 77 similar to that of broilers so that the same methodologies for the estimation of meal criteria 78 could be used. We tested this hypothesis with data that were collected in several separate 79 experiments, with birds of different ages and under different conditions for the three species. 80

In addition, we tested whether or not the main principle upon which the methodologies 81 developed by Howie et al., (2009a) are based, that is, a continuous increase in the probability 82 of birds starting to feed with time since the last meal, applies to birds of each of these species. 83

We also investigated how appropriate disaggregation of the data can aid in fully 84 understanding the structure of feeding behaviour. Finally, we briefly describe the observed 85 feeding behaviour of these three species after grouping it into meals. 86

MATERIALS AND METHODS 88

Records of visits to feeders of 3470 female broiler chickens (Gallus gallus), 3314 male 89 turkeys (Meleagris gallopavo) and 480 male and female Pekin ducks (Anas platyrhynchos 90 domestica) were available for analysis in this study (see summary in Table 1). The methods 91 and equipment for obtaining the basic duck and broiler data have been previously described in 92 detail by [START_REF] Bley | Recording of individual feed intake and feeding 408 behavior of Pekin ducks kept in groups[END_REF] and Howie et al., (2009a), respectively, but data were 93 analysed here using novel methods. The turkey data were collected from a set of 16 hatches. 94 Each hatch, consisting of around 200 male birds, was housed from 18 to 22 weeks of age in a 95 single pen. The actual number of turkeys per pen varied slightly due to differences in the 96 number of available birds per hatch. 97 Pens for broilers were equipped with one and pens for ducks and turkeys with two 98 feeding stations. Each feeding station, previously described in detail for ducks (Bley and 99 Bessei 2008) and broilers (Howie et al., 2009a), consisted of 8 feeders and was linked to a 100 computer to allow automatic recording of visits. The feeding stations for turkeys were scaled-101 up versions of the ones used to collect broiler data. Each feeder had a back bar and side plates 102 that were adjusted as the birds grew to allow entry of only one bird at a time. Each feeder 103 contained a feeding tray that was linked to electronic scales to record the weight of food at the 104 start and end of each visit. All birds were tagged with electronic wing bands and a radio 105 frequency antenna system was used to identify individuals entering and leaving the feeders. 106

Start and stop time, weight of food consumed, bird ID, visit duration, date, pen and feeder 107 number were recorded per visit and stored electronically in a database. 108 Birds of all species were placed in their pens at least a few days before data collection 109 began to allow acclimatisation to the environment and feeding equipment. Birds had ad 110 libitum access to a species-appropriate pelleted feed throughout the data collection period. 111

Lighting regimes and stocking densities differed between the species, with turkeys having the 112 most hours of darkness and ducks having the lowest stocking density (Table 1). 113

[Insert Table 1 around here please] 114

Analysis of feeding behaviour 115

The data were screened to remove visits where the wing band of the bird was not recorded, 116 which affected less than 0.1% of the total number of broiler and turkey visits. Scale errors 117 were also removed from the calculations of feed intake, but were included for other 118 characteristics (less than 0.5% of all visits). On rare occasions, ducks were not properly 119 First the interval length between two consecutive visits to feeders of the same bird was 122 calculated. The frequency distributions of these interval lengths, as well as of log e -123 transformed interval lengths (measured in s), were plotted to assist in determining the 124 structure of short-term feeding behaviour and the estimation of meal criteria. On the basis of 125 previous experience, bin-widths of 5 min and 0.5 log e -units were selected to present the 126 clearest graphs. 127

The effects of data pooling (Morgan et al., 2000b;[START_REF] Yeates | Consequences of variation in 466 feeding behaviour for the probability of animals starting a meal as estimated from 467 pooled data[END_REF] on the 128 distribution of interval lengths and on starting probabilities were investigated by 129 disaggregation of the data into sub-sets. First, 'day-time' data sets were produced for each 130 species that consisted of intervals that occurred entirely during the light period only. For each 131 species, day-time intervals of all birds were further disaggregated into two groups, that is, (i) 132 intervals between visits to the same feeder and (ii) intervals between visits to different 133 feeders. After meal criteria were estimated (see below) three additional data sets were created 134 of birds with similar feeding strategies in each species for further analyses. To that end, first 135 the mean number of daily meals was calculated per bird. For each species, data of three sub-136 groups of 50 birds each were pooled. These sub-groups consisted of birds with a mean daily 137 meal number that was (i) around the average or (ii) the lowest or (iii) the highest of the total 138 population. To further investigate the structure of short-term feeding behaviour of ducks, we 139 calculated for each duck the number of intervals with an intermediate duration (between 1 and 140 10 min) as a proportion of all intervals between visits to feeders. Two data sets were created 141 by pooling the data of 50 ducks each with either (i) the lowest or (ii) the highest proportion of 142 such intermediate intervals. normal model was fitted to the distribution of log e -transformed between-visit interval lengths 145 using GENSTAT (VSN International 2008), as described in detail by Howie et al.. (2009a). 146

The model was fitted to the lengths of day-time intervals longer than 7.5 log e units and has the 147 following probability density function (PDF): 148

PDF = (1/cunormal((7.5-µ)/σ))(1/(2.506628 σ))exp(-((x-µ) 2 )/(2σ 2 )) 149
Where: cunormal = GENSTAT cumulative normal correction factor to allow for truncation, µ 150 and σ = mean and standard deviation of the log-normal distribution, and x = log e interval 151 length (in sec). The meal criterion was estimated at the interval length where the number of 152 observed intervals was twice that predicted by the model, as outlined by Howie et al. 2009a). 153

Meal criteria were also estimated on the basis of the probability of birds starting to eat 154 in relation to time since last feeding (P start ). The probability of birds starting to feed within the 155 next 5 min at time t since feeding last was calculated as the number of intervals > t and ≤ t + 5 156 min divided by the number of intervals > t min (Tolkamp and Kyriazakis 1999a). For the 157 estimation of meal criteria, these probabilities were also calculated with bin-width of 1 min. 158

As described previously (Howie et al., 2009a), the meal criterion is estimated as the time 159 since feeding last where P start is lowest, using a rolling average over 5-min intervals to reduce 160 the effect of random variation in values. 161

Meal criteria according to both methods were estimated per hatch. ANOVA was used 162 to test for an effect of methodology of estimation on resulting meal criteria estimates and the 163 associated meal characteristics. 164

Distribution of interval lengths between visits 170

Figure 1 (top row) shows the relative frequency distributions of the length of intervals 171 between visits to feeders for all data pooled per species. Broilers, turkeys and ducks all 172 showed a rapid decrease in frequencies with increasing interval length to a minimum between 173 15 and 30 min. The frequencies then increased to a peak between 50 and 80 min, and then 174 gradually decreased to very low frequencies at long intervals. Although the values of the 175 minima and maxima varied between the species, all species show a similarly shaped 176 distribution of between-visit interval lengths.

[Insert Figure 1 around here please]

177 Log e -transformation of interval lengths resulted in the distributions shown in Figure 1 178 (centre row). From the data obtained with turkeys, it was evident that there was a population 179 of very long intervals, longer than approximately 10.5 log e -units (corresponding to 10 h), that 180 was almost entirely separated from the remainder of the interval distribution. These very long 181 intervals all included at least part of the dark period. When the three data sets were 182 disaggregated by removing all intervals that included the entire dark period or parts thereof, 183 the separate distribution for very long intervals in turkeys completely disappeared (Figure 1, 184 bottom row). The same procedure also removed 'blips' that were previously observed in the 185 frequency distribution of long log e -transformed intervals for broilers (around 9.6 log e -units, 186 corresponding to 4 h) and ducks (compare centre with bottom row graphs in Figure 1). The 187 remaining distributions of the population of longer log e -transformed intervals were 188 approximately normal in all species. Figure 1 shows that, apart from the approximately log-189 normal distribution of a population of longer intervals, there is at least one additional 190 population of shorter log e -transformed interval lengths for broilers and turkeys and there are 191 at least two for ducks. These are investigated in more detail below. 192 decrease in P start to a nadir between 20 and 30 min was followed by an increase to a plateau or 197 even a later decrease. As this may be an effect of pooling across day and night data (Morgan 198 et al., 2006b), the intervals that included (part of) the night period were removed, resulting in 199 the probabilities depicted by the graphs in the middle row of Figure 2. The bottom row of 200

Figure 2 shows the effects of disaggregation by feeding strategy on P start estimates. In contrast 201 with the trend seen in the pooled data, P start generally continued to increase with time since 202 feeding last for birds with a given feeding strategy. 203

[Insert Figure 2 around here please]

204

Effect of disaggregation of interval data by feeder visited 205

For ducks, with few very short between-visit intervals, the sub-set of day-time intervals 206 between visits to the same feeder had virtually the same distribution as the sub-set of day-time 207 intervals between visits to different feeders (Figure 3). Disaggregation of data obtained with 208 broilers and turkeys, however, showed that very short intervals were recorded between visits 209 to the same feeder only (Figure 3, centre row graphs) and not between visits to different 210 feeders (Figure 3, bottom row graphs). For broilers, the frequency distributions of the log e -211 transformed length of intervals between visits to different feeders clearly showed two 212 overlapping populations that were both approximately log-normally distributed (Figure 3). 213

For turkeys, the data suggest that there is a population of shorter intervals, similar to that 214 observed in broilers but much smaller, that overlaps with the log-normally distributed 215 population of between-meal intervals. 216 Duck data were examined in more detail in an attempt to find an explanation for the 219 occurrence of three populations of intervals between visits to different feeders rather than the 220 two that were observed in birds of the other two species. A preliminary inspection of interval 221 distributions obtained with individuals showed that there was little variation between ducks in 222 the distribution of the populations of very short (with a peak around 2.75 log e -units 223 corresponding to 15 s) and very long (with a peak between 8 and 9 log e -units, corresponding 224 to 50 and 135 min) intervals. There was, however, considerable individual variation in the 225 number of intervals between 1 and 10 min, corresponding to 4.1 and 6.4 log e -units, as a 226 percentage of all intervals (from 1 to 46%). Figure 4 distinguished from the other two populations of intervals (Figure 4). 233

[

Estimation of meal criteria 234

A truncated normal function describing all pooled log e -transformed day-time intervals longer 235 than 7.5 log e -units gave a good fit to the data pooled across species (Figure 1, bottom row 236 graphs). The model converged easily for all data sets and species-specific meal criteria could 237 quickly be estimated (Table 2). Similarly, a clear trough in the plot of the probability of birds 238 starting to feed in relation to time since last feeding (Figure 2, centre row) allowed an easy 239 estimate of meal criteria for each species by this method. Meal criteria estimated per hatch in 240 this manner were 150, 70 and 75 s shorter for broilers, ducks and turkeys, respectively, than 241 estimates resulting from the truncated normal method. Because of the scarcity of intervals in 242 this range, the effect of these shorter meal criteria on average number of daily meals (an 243 11 increase with less than 0.1 in each species) and other meal characteristics was, however, very 244 small. Meal criteria estimated by the truncated log-normal method were used to group visits 245 into meals for further analyses (all between-feeding intervals shorter than the meal criterion 246 were ignored for the calculation of meals). 247

[Please insert Table 2 around here]

248

Meal characteristics 249

Broilers and ducks had a very similar average daily number of meals but turkeys consumed 250 their food in considerably fewer meals (Table 2). Ducks not only had the shortest meals but 251 also spent the smallest proportion of total meal duration feeding (24.1% vs. 70.6% and 81.8% 252 for broilers and turkeys, respectively). This resulted in ducks having by far the shortest daily 253 feeding times (less than 12 min/d, compared with 34.2 and 63.6 min for turkeys and broilers, 254 respectively; Table 2). 255 256 DISCUSSION 257

The main objective of this study was to test the hypothesis that the same methods could be 258 applied for the estimation of meal criteria in broilers, ducks and turkeys because of a similar 259 structure of their feeding behaviour. The distribution of longer (that is, between-meal) 260 intervals has a major effect on meal criteria estimates and this distribution is, therefore, 261 discussed first. 262

Structure of feeding behaviour: the distribution of longer intervals 263

Plots of the frequency distribution of log e -transformed interval lengths between behavioural 264 events can reveal much about the structure of animal behaviour (Tolkamp et al., 1998a;265 Yeates et al., 2001). Figure 1 shows that the distribution of interval lengths between visits 266 was clearly not consisting of just a single interval population in any of the three species, 267 which is evidence for a bouted structure of behaviour. Most of the longer intervals in each 268 species were part of a skewed normal distribution that could be normalised by log e - 13 meals has many short and very few long intervals between meals. In contrast, a bird with few 295 daily meals will have few, mainly long, intervals between meals. This will result in a higher 296 average P start for the bird with many than for the bird with few daily meals at any time since 297 the last meal. However, even if P start increases for both animals with time since the last meal, 298 this may not be so when the data of the animals are pooled (Morgan et al.,., 2000b). Since 299 young/small birds usually have more daily meals, and therefore a higher P start , than 300 older/larger birds (Howie et al., 2009a;b), disaggregation by age is in essence also a 301 disaggregation by feeding strategy. Figure 2 shows that in all species, when data were 302 properly disaggregated, P start continued to increase with time since the last meal, in a manner 303 that can be expected on the basis of the satiety concept [START_REF] Yeates | Pooling of between-feeding intervals across day and night or across individuals with different 290 feeding strategies can obscure real changes in starting probability with time since the last 291 meal for an individual at a given time[END_REF]. In the pooled 304 data set, however, the estimated P start is consistent with a log-normal distribution of intervals 305 between meals in broilers, turkeys and ducks and this resulted in similar distributions of 306 longer between-feeding interval lengths in all three species. 307

Estimating meal criteria 308

There were large numbers of short intervals, especially for broilers and turkeys, that were 309 clearly not part of the log-normal distribution of the population of longer, that is, between-310 meal, intervals (Figure 1). It was not immediately clear how many populations of short 311 intervals there were and how each of these was distributed. For such situations, Howie et al., 312 (2009a) developed two methods that allow estimation of meal criteria on the basis of broiler 313 data. The method based on fitting a truncated log e -normal model to the distribution of long 314 intervals only, suited the duck and turkey data as well (Figure 1). The second method 315 developed with broilers relies on estimation of the trough in starting probabilities calculated 316 from pooled data (Howie et al., 2009a). Such a trough is also clearly observed in data 317 obtained with ducks and turkeys (Figure 2). Meal criteria that were estimated with this, rather 318 than the truncated log-normal method, resulted in similar predictions of daily meal number 319 (Howie et al., 2009a,b). The hypothesis that disaggregation of data in 325 subsets of intervals in which drinking did or did not occur would assist model fitting proved 326 to be wrong for broilers (Howie et al., 2009a). In the present study we further explored the 327 use of disaggregation of pooled data into subsets, which showed that very short intervals were 328 not recorded between visits to different feeders. It will take more than a few seconds for a bird 329 to leave a feeder and access another one (certainly if adjacent feeders are occupied by other 330 birds), which explains the absence of very short intervals between visits to different feeders. It 331 is not immediately clear, however, what caused the considerable number of very short 332 intervals between visits to the same feeder in broilers and turkeys (Figure 3). A temporary 333 loss of contact between the tag on the bird and the RFI antenna system for certain positions of 334 a bird that remained in a feeder seems a more plausible explanation. Until that is validated 335 (for example by means of video recordings during an experiment), this suggestions remains, 336 however, speculative. 337

In the duck data collection, such very short intervals had already been removed from 338 the data set that was available for analysis, but they occurred only sporadically. This could 339 well have been caused by a difference between feeder systems in the sensitivity of continuous 340 bird identification. In the pooled duck data, log-transformation of interval length suggested 341 that there were three populations of between-feeding intervals (Figure 1). Inspection of 342 individual data showed that one log-normal distribution of short intervals and one log-normal 343 distribution of long day intervals (with a peak between 1 and 2.5 h) occurred in all birds. A 344 turkey data were obtained from birds that were more mature than the birds from the other two 373 species, this may not be solely a species effect. Howie et al. (2009a;b) observed a trend of 374 fewer and larger meals from electronic feeders in broiler lines as birds increased in age and 375 weight and this will have affected any comparisons of meal patterns across species here. In 376 addition, birds of all species consumed most of their feed during the light period, which was 377 shortest in the experiment involving turkeys. This will have stimulated turkeys to consume 378 their daily intake in a shorter time, which must have resulted in a relatively higher bird 379 pressure per feeder in turkeys compared to other species than suggested by the data in Table 380 1. Such an increase in pressure per feeder may well have contributed to increased visit and 381 meal sizes, as has been observed in other species (Nielsen et al., 1995). 382

In conclusion, the same methodologies can be applied to investigate the feeding 383 behaviour of the three bird species included in this study. The frequency distribution of 384 longer, between-meal, intervals was very similar in broilers, ducks and turkeys. This was a 385 direct result of similar changes in the probability of birds starting to feed with time since last 386 feeding, which could be estimated accurately because very large data sets of feeding 387 behaviour were available for the present study. As a result of this similarity, methods that 388 were developed for the estimation of meal criteria in broilers, based on fitting a truncated log-389 normal function or on analysis of changes in P start , could be applied to data obtained with 390 turkeys and ducks. This was despite considerable differences between species in the 391 distribution of shorter, that is, within-meal, intervals. Disaggregation of data that were 392 originally pooled across day and night, across all individuals and across visited feeder 393 numbers provided a powerful tool to further the understanding of the structure of short-term 394 This revealed that the feeding behaviour of all three avian species is underpinned by the same 396 principle, that of satiety. The quantitative analysis of such behaviour will not only improve 397 our understanding of the role of hunger and satiety in food intake regulation but could also 398 provide additional traits for selecting the most desirable future genotypes of domestic poultry 399 species. 400 to feeders recorded with broilers, turkeys and ducks after deleting intervals that include (part 499 of) the dark period (all bin widths 0.5 log e -units). The graphs show the frequency distributions 500 of the pooled log e -transformed intervals (top row), intervals between visits to the same feeder 501 only (centre row) and intervals between visits to different feeders only (bottom row). 502 503 Figure 4. Frequency distributions of log e -transformed intervals between visits to feeders that 504 were observed in ducks (bin widths 0.5 log e -units). Graphs show the distribution of all data 505 pooled (left-hand graph) and of data pooled across 48 birds (10% of the total) with a number 506 of intervals between 1 and 10 min that, as a proportion of all intervals, was either lowest 507 (from 0.01 to 0.04; n = 12,303; centre graph) or highest (from 0.21 to 0.48; n = 22,865; 508 right-hand graph). 509

  -term feeding behaviour of broiler chickens of different genetic lines to allow 73

  feeders, which resulted in many short 'between-feeding' intervals which 120 were removed before analyses. 121

  143

  used to estimate meal criteria per hatch. First a truncated log-144

9

  Figure 2 (top row) shows how the probability of birds starting to feed within the next 5 min 195

  Insert Figure 3 around here please] 217 Effects of disaggregation of duck data by individual feeding strategy 218

  shows the observed frequency 227 distributions of interval lengths pooled across the 10% of individuals with a low or a high 228 proportion of intervals in the range of 1 to 10 min. The Figure demonstrates that a 229 considerable proportion of ducks showed little evidence of a third population of intervals. At 230 the same time, another considerable proportion of ducks produced a relatively large third 231 population with 'intermediate' lengths (from around 1 to around 10 min) that was very clearly 232

  measured with electronic feeders in the poultry species considered here. 395

Figure 1 .Figure 2 .Figure 3 .

 123 Figure 1. Frequency distributions of (log e -transformed) interval lengths between visits to 474

  Figure 1 510

Table 1 .

 1 Details of experimental setup for the collection of short-term feeding behaviour data of 538

	27

that underlie food intake regulation[START_REF] Lemagnen | Hunger[END_REF][START_REF] Zorrilla | Measuring meals: structure of prandial food and water intake of rats[END_REF] but could also

assist in identifying desirable traits for animal breeding programmes(Howie et al., 2009b).

E-mail: br.poultsci@bbsrc.ac.uk URL: http://mc.manuscriptcentral.com/cbps British Poultry Science

[START_REF] Yeates | Consequences of variation in 466 feeding behaviour for the probability of animals starting a meal as estimated from 467 pooled data[END_REF] and chickens(Savory, 1980; Howie et al., 2009a) have a much lower

probability of feeding in dark than in light conditions. As a result, between-feeding intervals

are on average longest when these include part or all of the dark period. In the present

analysis, this was shown most clearly by the separate population of very long log e -

for broilers can be successfully applied to estimate meal criteria in turkeys and ducks.

well understood what caused the observed distribution(s) of intervals shorter than the

very rare in other birds (Figure4). This suggested clear individual differences between ducks

in the structure of short-term feeding behaviour. A similar individual variation in the number

of populations of between-feeding intervals has been observed in cows.(Tolkamp and

parameter estimates for feeding pattern and performance test traits in pigs. Animal

Science,

space feeders. Livestock Production Science 44: 73-85.

SAVORY, C.J. (1980) Diurnal feeding pattern in domestic fowls. Applied Animal Behaviour

Journal of TheoreticalBiology,

Table 2. Summary of mean (± standard error) meal characteristics for broilers, ducks and turkeys.

Acknowledgements 401

The authors would like to thank the BBSRC, Aviagen Ltd. and Genesis Faraday for financial 402 support for this project; to Aviagen Ltd. for providing the broiler and turkey data and to Georg 403 Stolle GmbH for providing the duck data for this study. SAC receives support from the 404 Scottish Government. 405 406


Kelly A Drake

Christl A Donnelly

Marian Stamp

Prof Stamp Marian

Dawkins

The influence

Keywords: Feather pecking, Feathers, Welfare

come

A major welfare problem in the commercial egg production industry is that of 58 injurious feather pecking (FP) in laying hens (Savory, 1995; [START_REF] Green | Cross-sectional study of the 417 prevalence of feather pecking in hens in alternative systems and its 418 associations with management and disease[END_REF]59 Bright, 2009;[START_REF] Bestman | Influence of farm 380 factors on the occurrence of feather pecking in organic reared hens and 381 their predictability for feather pecking in the laying period[END_REF]. Injurious FP leads to increased feed 60 consumption due to heat loss [START_REF] Tauson | Influence of plumage condition on the 460 hen's feed requirements[END_REF], a reduction in egg 61 production (El-Lethey et al., 2000), pain and suffering of the injured birds (Gentle and 62 Hunter, 1991) and increased bird mortality, including cannibalism (Huber-Eicher and 63 Sebo, 2001). 64

In 2012, barren cages will be banned in the European Union in line with 65 Directive 1999/74/EU. This will increase the number of birds kept in non-cage laying 66 systems (barn, colony, free range and organic), which in turn will increase the 67 numbers of birds at risk of injurious FP and cannibalism [START_REF] Blokhuis | The LayWel 384 project: welfare implications of changes in production systems for laying hens. 385[END_REF]68 Fossum et al, 2009). Beak treatments that blunt the beak and so reduce the impact of 69 pecking either by infra-red or hot blade [START_REF] Dennis | Infrared beak treatment 395 method compared with conventional hot-blade trimming in laying hens[END_REF] remain the main methods 70 of controlling FP, but raise welfare issues in their own right [START_REF] Gentle | 411 Behavioral evidence for persistent pain following partial beak amputation in 412 chickens[END_REF]71 Hughes and Gentle, 1995). Furthermore, beak treatments of all types will be 72 banned in the UK from 2011. There is therefore an urgent need to find ways of 73 controlling FP without resorting to beak treatment. 74 Despite the much greater understanding of the factors predisposing hens to 75 feather peck that has been gained from research over the past 25 years, prevention is 76 still not possible [START_REF] Rodenburg | Feather pecking in laying hens: new insights and directions for 446 research?[END_REF][START_REF] Dixon | Feather pecking behaviour and associated welfare issues in 400 laying hens[END_REF]. The problem is multi-77 factorial and stems from interactions between the bird, the environment and 78 management variables in ways that are not yet understood (Rodenburg et al., 2008a). [START_REF] Gunnarsson | Effect of rearing 420 factors on the prevalence of floor eggs, cloacal cannibalism and feather 421 pecking in commercial flocks of loose housed laying hens[END_REF]van der Weerd, 2006, Staack et al, 2007;Riber et al, 82 2007;Rodenburg, et al., 2008b) but it is not clear whether particular factors are 83 critical or whether it is the change between rearing and lay factors that is most 84 important. However, even if it is not currently possible to prevent FP altogether, it 85 would greatly help producers if they were able to predict outbreaks of FP before they 86 occur or at least detect them at the onset. This would allow action to be taken before 87 the welfare and production of the birds was adversely affected and to concentrate such 88 measures on high risk flocks. 89

The aim of this longitudinal study was to identify factors (bird, management 90 and environment) in the early environments of laying hens in commercial non-cage 91 systems that predict which flocks are at the greatest risk of developing FP later in lay. 92

Commercial flocks were followed from rear throughout the laying period until 93 clearance and we collected data on a variety of factors about the birds themselves 94 (strain, feather cover, feed intake) as well as the environments they were in. We 95 looked for signs in young flocks that might indicate they were at high risk of 96 developing FP later in life and also at factors in the rearing and laying environments 97 that might be associated with severe feather damage. We examined both the role of 98 particular factors in the rearing environment that might predispose an adult flock to 99 feather damage and also the role of changes between the rearing and the laying 100 environment that might constitute a particularly high risk. 101

MATERIALS AND METHODS 102

Approximately 335 000 commercially reared laying hens were followed from colony could contain between 780-4000 birds. As colonies within a house were not 109 fully independent, data were analysed statistically with house (n=44) as the 110 independent unit. 111

The study included three different types of laying systems: barn (2 houses/10 112 colonies), organic free-range (19 houses/19 colonies) and free-range systems (42 113 houses/55 colonies). Flocks were comprised of 5 laying bird hybrids: Hyline,114 Lohmann (Brown and Traditional), Shaver, Bovans Goldline, Columbian Black Tail 115 and a mix of Hyline and Goldline. Birds from 18 out of the 19 farms were beak-116 treated at 5-7 d old. One farm which did not beak-treat initially, had to beak treat two 117 colonies at 30 weeks of age. Another farm had to repeat the beak-treatment for 4 118 colonies at 35 weeks of age. The methods used for beak treatment were; infra-red (4 119 houses) and traditional hot-blade (40 houses). Each house was visited on at least 4 120 occasions; towards the end of rear (<17 weeks), after transfer to the lay house (~18-121 22 weeks), peak-lay (~23-30 weeks) and close to clearance (~50 wks). Additional 122 visits were made to some farms to establish a more thorough database of events. Due 123 to insufficient numbers in the barn systems and houses using infra-red beak 124 treatments, we were unable to meaningfully compare the impact of these 125 variables on propensity for feather damage. 126

Feather damage 127

Feather damage scores were recorded during each visit for each colony both inside the 128 house and from birds on the corresponding range outside the house by visual 129 inspection using the method described by [START_REF] Bright | A non-intrusive method of 387 assessing plumage condition in commercial flocks of laying hens[END_REF] (neck, back, rump, tail and wing) and 133 scored on a best (0) to worst (4) scale (Table 1). Feather damage scores were 134 collected during each visit and averaged to give a mean feather damage score for each 135 body region and an average total (that is,. summed) feather score for each colony. We 136 considered mean feather damage greater than or equal to the threshold of 3.8 (at any 137 age) to be substantial feather damage in an attempt to 'predict' whether a flock was at 138 risk of becoming a 'feather pecking flock'. 139

Management and husbandry 140

The first visit was conducted at the rearing house (12 -17 weeks of age). This visit 141 gathered detailed information on general management, husbandry practices and the 142

Environmental variables 159

Environmental variables were measured during each visit. Within each colony, 4 160 locations were chosen randomly using a grid map, two in the slatted area and 161 two on litter. Environmental measures were taken at all 4 locations and the mean of 162 these calculated for each colony. The measures taken were: sound (dB) intensity 163 (using a Sound level meter ST-8850, Farnell in One, Leeds, UK), lux (using a TES 164 1330A Digital Lux meter, York Survey Supply Centre, York, UK), litter pH and 165 temperature (using a HI-991300 pH/Temperature meter, Hanna Instruments, Bedford, 166 UK) and ammonia and carbon dioxide gas concentrations (5-100 ppm and 300-5000 167 ppm respectively) (using RAE gas detection tubes, RAE Systems Inc., California, 168 USA and a Gastec GV-100S pump, Gastec Corporation, Japan) were recorded. All 169 variables were recorded at bird height (~ 30 cm from ground). 170

Production variables 171

Weekly production records were collected by the producers and included percent of 172 birds in lay, percent mortality and feed consumed (gram/hen/d). Production records 173 that were not directly supplied varied from farm to farm, and not all farms collected 174 the same information; however all recorded those listed above. 175

Statistical analysis 176

The independent unit for analysis was the house (n=44). The aim of the analysis was 177 to identify which factors contributed to the risk of 'failure', that is a given flock 178 yielding a mean feather damage score of ≥3.8. Although any arbitrary level of feather 179 damage could be defined as 'failure', 3.8 represents a substantial level when feathers 180 are severely damaged and/or areas of naked skin are visible (Table 1). This is the level 181 Table 2 shows that the feather damage score at a given age predicted the time 225 in the future when a flock would reach the FP threshold. (A unit = an increase of 1.0 226 in the average total feather score as defined in Table 1). Particularly notable is the fact 227 that predictions could be made even by observing young birds less than 20 week of 228 age, where there was relatively little feather damage (Figure 2). The feather damage 229 scores for birds 17-20 weeks ranged between 0.03-1.18. Nevertheless, the feather 230 Neither % mortality in the flock nor the % of birds in lay was predictive of when that 240 flock would reach a FS of ≥3.8 (for mortality p>0.1 at all ages; for % birds in lay 241 p>0.5 at all ages). However, the mean amount of feed eaten (g/day per individual) 242 was significantly predictive, at least when birds were less than 17 weeks and between 243 20 and 24 weeks of age, indicating that the more feed that was eaten, the earlier 244 failure time occurred (Table 4). 245

Environmental variables 246

The levels of the environmental variables recorded (carbon dioxide (CO 2 ), ammonia 247 (NH 3 ), light (lux), noise (dB), litter pH and temperature ( 0 C) are shown in Table 5. 248

In laying houses, higher CO

Environmental factors during rearing 267

Factors in rearing that influenced FP later in lay are shown in Table 6. The type of 268 feeders and drinkers had a significant effect on age at which FP developed. FP 269 developed earlier in flocks that came from rearing houses with chain feeders than 270 from those with pan feeders or a combination of feeder types. FP developed earlier in 271 laying flocks that had been reared in houses with a bell and nipple drinker system than 272 those with nipples only, or nipple/cup systems. 273

Changes from rearing to laying environment 274

Table 7 shows the effects of changes from the rearing environment to the laying 275 environment. Where the feeder system did not change from rear to lay, FP was found 276 to start sooner than when the feeder system changed between farms (Table 7). 277 However, it should be noted that the only recorded instances of where the feeder 278 system was the same in rear and in lay were those in which there was a chain feeder in 279 both. Chain feeders appear to be a risk factor in themselves (Table 6). An earlier start 280 to FP occurred earlier in lay with birds that were moved to a different farm (Table 7). 281

To obtain an idea of whether FP was affected by the number of changes 282 between rearing and lay, we added together the effects of all recorded changes 283 (veranda, perches, feeder type, drinker type, lighting, transfer to a different lay farm). 284 This is shown as 'sum' in the bottom row of Table 7 and Our results also show that it is possible to predict which flocks are at greatest 297 risk of feather pecking before serious feather damage is apparent. Even in young birds 298 (under 20 weeks of age), when very little feather damage is seen in any flocks, slight 299 differences in feather score are predictive of the level of feather damage at later ages 300 (Table 2). In other words, even slightly raised feather scores in young birds are 301 associated with earlier onset of serious feather damage, supporting similar studies by 302 [START_REF] Bestman | Influence of farm 380 factors on the occurrence of feather pecking in organic reared hens and 381 their predictability for feather pecking in the laying period[END_REF]. This means that just by looking at a 303 Another factor that is suggestive of future problems is feed intake. Flocks 306 that showed early signs of increased daily feed intake were also likely to show earlier 307 severe feather damage (Table 4). However, this was only shown to be significant 308 between 20 -24 weeks of age. This is of interest as it is known that birds increase 309 their feed consumption due to heat loss, if, severely feather pecked (Tauson and 310 Svensson, 1980). Therefore, the first signs of an increase in food consumption may 311 indicate a measure in which to 'predict' a problem before it becomes an issue of 312 welfare or productivity. 313 that they are associated with more restricted feeding would be well worth further 336 investigation. Although our data are suggestive rather than conclusive, a lack of a 337 veranda for young birds during rearing may also be associated with earlier risk of 338 feather pecking. (The value of providing verandas for young birds could usefully be 339 explored). Among environmental factors, poor air quality (levels of CO 2 and 340 ammonia) and higher light levels predispose flocks to develop feather pecking at an 341 earlier age (Table 6). 342

Bright (2009) and

In addition, increased sound levels within a house (up to 20 weeks of age) 343 were associated with an early propensity to feather peck. However, as in a study by 344 [START_REF] Bright | Vocalisations and acoustic parameters of flock noise from 390 feather pecking and non-feather pecking laying flocks[END_REF], it is not clear whether the observed effects were due to noise made by 345 the birds themselves (birds that vocalise a lot have a tendency to FP) or due to 346 environmental noise increasing the tendency to FP. Either way, the role of sound 347 deserves more attention in future [START_REF] Bright | Vocalisations and acoustic parameters of flock noise from 390 feather pecking and non-feather pecking laying flocks[END_REF]. It could either be a useful indicator 348 that a given flock is 'at risk' of developing FP or a pointer to the relatively easy 349 intervention of reducing noise levels to reduce risk of FP. 350

We then examined the effects of change between rear and lay. One factor 351 that seemed to be of considerable importance was whether birds moved farms 352 between rear and lay. Although the numbers reported here are small, there is a strong 353 7). This might be because birds staying on the same farm do not 355 experience a long journey or it could be that where rearing and laying houses are on 356 the same farm, they are more likely to provide more similar conditions than if they are 357 on different farms. We attempted to test the idea that 'amount of change' in 358 environmental conditions was important by looking at the effects of the number of 359 changes between rear and lay. We failed to detect any additive effect of the number 360 of changes (Table 9). Nevertheless, we suggest that further studies of the transition 361 between rearing and laying environments could be very valuable. Keeping birds on 362 the same farm throughout their lives is not usually possible, but more attention to the 363 differences they experience as they move from rear to lay might suggest ways of 364 reducing the chances of severe feather damage later on. 365

In conclusion, it is possible to predict which flocks are at risk of FP before 366 serious feather damage has occurred later in lay. Given the multifactorial nature of 367 FP and the difficulties of eliminating it altogether, the ability to identify 'at risk' 368 flocks could still be of value to producers since it could enable them to target 369 preventive action specifically on the flocks most at risk. Future research aimed at 370 reducing the risk of feather pecking could profitably concentrate on the role of feeder 371 layout, air quality, and light and sound levels, as well as the role of changes between 372 rearing and laying environments. 373

  79 Environmental factors experienced by birds during rearing have been identified as 80 particularly important to the development of later FP in adult flocks (Johnsen et al.,

  12 103 rearing farms on to 19 laying farms between February 2006 and August 2008. The 104 laying farms consisted of 44 houses, the majority of which were internally sub-105 divided into colonies (birds physically separated by a barrier but within the same 106 internal barriers between flocks) or a single undivided house. A single 108

  bird. The following were recorded: season of rear and hatch month, size of farm 143 (number of houses, numbers and ages of birds currently on farm, strain of bird, 144 age of parent flock, flock size, stocking density, drinker type (bell, bell and 145 nipple, nipple, nipple with cup), number of drinkers per house, feeder type 146 (chain, chain and pan, pan), number of feeders per house, litter type (cut straw, 147 newspaper, woodchip), lighting source/number (fluorescent, tungsten, daylight, 148 redlight or combination, enrichments such as perches, bales etc. Birds were 149 transferred to the laying houses between 17 -18 weeks. A record was kept of 150 whether the laying houses were on the same or a different farm. The first visit to the 151 laying farm (between 18 and 22 weeks of age) consisted of recording the 152 management, husbandry practices, bird, environment and production variables listed 153 above and in addition recording details of the laying system (barn, free-range, 154 organic), other species on farm, age at transfer, verandas (Y/N) % of house floor 155 slatted or litter, range size, % range area covered by vegetation, vegetation type 156

  Figure1shows initial bird numbers on transfer into the lay houses (n=44), final bird 214

Table 3 .

 3 Chain feeders were significantly associated with earlier failure times than 235 pan feeders. Low feeders (those on the ground) were associated with earlier onset of 236 FP than High (raised above the ground). Pan feeders were always raised above 237 ground level. 238 Production 239

  2 levels were associated with earlier onset of FP: 249 between 24 and 30 weeks of age, each 200 ppm increase in CO 2 was associated 250 with a 14.8% reduction in time to failure (95% confidence interval -19.7% --251 9.5%; p=0.0001). Higher ammonia levels were also associated with earlier onset 252 of FP: every 15 ppm increase in NH 3 recorded between the ages of 15 and 17 253 weeks was associated with a 10.1% reduction in time to failure (CI -16.2%--risk factor, particularly if light levels were high in 257 young birds. Higher light levels in birds of 17-20 weeks were associated with an 258 earlier onset of FP: each 100 lux increase was associated with a 12.2% reduction 259 in time to failure (C.I.: -18.9%--3.9%; p=0.0034). The final factor we found to 260 be associated with earlier onset of FP was sound level. Between 15 and 17 weeks, 261 each 10 dB increase in sound was associated with 25.5% reduction in time to 262 failure (C.I.= -39.6% --8.2%; p=0.0056) and between 17-20 weeks, with a 7.9% 263 reduction in time to failure (C.I.= -13.5% --2.0%; p=0.0099). No significant 264 differences were found at any age category for either litter pH (p>0.3) or for 265 temperature (p>0.05) measured during the visit. 266

  was not associated with an 285 earlier risk of feather damage. 286 Birds hatched as chicks in July-March showed a delay in reaching the feather 287 score of ≥3.8 of 17.2% compared to birds hatched in April, May or June (2.9-33.5%, p 288 =0.0169) indicating FP started earlier for those hatched April-June. 289 DISCUSSION 290 Our results show that the age at which a flock exhibits substantial feather 291 damage can be predicted both by factors in the environment and by early 292 symptoms in the birds themselves. Environmental actors that were associated 293 with earlier onset of severe feather damage included the presence of chain 294 feeders, raised levels of carbon dioxide and ammonia, higher sound and light 295 levels, particularly in younger birds. 296

  While our results are consistent with the previous studies that have 314 emphasized the factors in the rearing environment that influence feather pecking 315 in later life (Blokhuis & van den Haar, 1989, 1992; Norgaard-Nielsen et al., 316 1993; Johnsen et al, 1998; Newberry et al,, 2007), we have here attempted to 317 separate the influence of factors in the rearing environment per se from the 318 influence of changes between rearing and laying environments. For example, 319 factors such as light levels in rearing might appear to have little effect on 320 likelihood of feather damage in lay (Kjaer & Sorenson 2002), but a change in 321 light level as the birds were moved from rear to lay might have a much bigger 322 effect. We therefore asked separate questions about the factors in rearing that 323 were associated with later feather pecking and about whether or not birds had 324 experienced a change in those factors as they were moved from rearing to laying 325 houses. 326 The accelerated failure time models used in this study point to a number of 327 factors in rearing that are associated with earlier onset of serious feather damage. 328 to feather damage and subsequent FP. The possibilities that low 334 feeders may hamper movement of an attacked bird, lead to feather damage or 335

  on the same farm may postpone the risk of feather pecking in 354 lay (Table

Figure 1 .Figure 2 .

 12 Figure 1. Initial bird numbers on transfer to the lay house and incidence of FP in the 470

  Figure 1.

Table 1 .

 1 Feather damage score

	Tables
	Score	Description of body
	0	Well feathered body parts with no or little damage
	1	Slight damage to any area of the body with feathers ruffled, body
		completely/almost completely covered
	2	Severe damage to feathers, but localised naked area (<5cm 2 )
	3	Severe damage to feathers, and large naked areas (>5cm 2 )
	4	Severe damage to feathers, >5cm 2 naked area and haemorrhage or broken
		skin

Table 2 .

 2 Feather damage scores (FS) in birds of different ages as predictors of the future time at which a house would reach a mean feather score of 3.8 or more.

	Age in	Estimated	95%		p-	Comments
	weeks	effect	confidence interval	value
	15-17	30.3%	-54.3%	271.7%	0.62
						Each 1 unit increase in FS
	17-20	-38.2%	-55.9%	-13.5%	0.005	associated with 38.2%
						reduction in time to failure
	20-24	-16.2%	-47.3%	33.1%	0.45
						Each 1 unit increase in FS
	24-30	-15.0%	-25.6%	-2.9%	0.017	associated with 15.9%
						reduction in time to failure
						Each 1 unit increase in FS
						associated with 9.6%
	30-40	-9.6%	-16.1%	-2.7%	0.007
						reduction in time to failure

Table 3 .

 3 Management systems and husbandry practices as predictors of the time at which a house would reach a mean feather score of 3.8 or more.

		Estimated	95%		p-	Comments
		effect	Confidence interval	value
	Organic *	-6.6%	-18.9%	7.4%	0.34
	(Y/N)
	Veranda	-7.6%	-19.4%	6.0%	0.26
	(Y/N)
	Perch	-7.1%	-19.2%	6.7%	0.30
	(Y/N)
	Feeder **	-19.7%	-31.9%	-5.3%	0.009 Houses with chain
	(Chain/pan)					feeders failed 19.7%
						sooner than pan
	Feeder ht	21.1%	5.9%	38.4%	0.005 Houses with high
	(H/L)					feeders failed 21.1%
						later than low
	*This analysis compared free-range with organic and omitted barn systems
	**This analysis omitted houses that had both chain and pan (n=3).

Table 4 .

 4 Daily feed intake (grams/hen/day) at different ages as a predictor of the time at which a house would reach a mean feather score of 3.8 or more.

	Age	Estimated	95%		p-	Comments
	(weeks)	effect	Confidence interval	value
	15-17	-1.0%	-1.78%	0.0%	0.041 Based on very limited data
	17-20	-2.6%	-11.7%	7.5%	0.60
	20-24	-13.4%	-23.7%	-1.8%	0.025 Each 20 g/h/d increase in
						feed associated with a
						13.4% reduction in time to
						failure
	24-30	-1.0%	-5.6%	3.9%	0.67
	30-40	-0.6%	-3.1%	2.0%	0.68

Table 5 .

 5 Levels of environmental variables measured.

		Mean (sd)	Range
	Light (lux)	29.6 (65.4)	2.0 -869.1
	Sound (dB)	59.4 (12.7)	14.3 -80.0
	CO 2 (ppm)	586 (327)	43-2000
	Ammonia (ppm)	21.9 (18.4)	0-100
	Litter temp. ( o C)	17.5 (4.5)	5.7-27.9
	Litter pH	7.13 (2.5)	1.14-13.62

Table 6 .

 6 Factors in rear as predictors of time at which a house reached a mean feather score of 3.8 or more.

	Reared	Estimated	95%		p-	Comments
	with	effect	Confidence interval	value
	Chain	-26.8%	-41.6%	-8.2%	0.0068	Houses with chain
	feed					feeders in rear failed
						26.8% sooner than
						houses with both chain
						and pan in rear
	Bell	-15.0%	-26.3%	-2.0%	0.0255	Houses with bell
						drinkers in rear failed
						15% sooner than
						houses with nipple +
						cup drinkers in rear
	Bell/nipple -39.6%	-50.6%	-26.1%	<0.0001 Houses with both bell
						and nipple drinkers in
						rear failed 39.5%
						sooner than houses
						with nipple drinkers
	Nipples	-6.8%	-23.8%	14%	0.49
	+/-cups
	Light type 29.8%	6.9%	57.8%	0.0086	Houses with
						fluorescent or natural
						light in rear failed
						29.8% later than
						houses with tungsten
						light in rear

Table 7 .

 7 Factors that changed between rear and lay as predictors of the time that a house reached a mean feathers score of 3.8 or more.

	Change	Estimated	95%		p-	Comments
	in	effect	Confidence interval	value
	Veranda	9.4%	-4.5%	255.4% 0.19
	in rear
	Y/N
	Perch	6.7%	-6.3%	21.7%	0.33
	Y/N
	Feeder	-19.2%	-28.5%	-8.7%	0.0006	Houses which had the
	type Y/N					same feeder type in rear
						and lay failed 19.2%
						sooner than houses of
						birds which experienced a
						change in feeder type
						from rear to lay.
	Drinker	-10.1%	-22.3%	-4.1%	0.15
	type Y/N
	Light	10.1%	-5.1%	27.6%	0.20
	type Y/N
	Farm	28.4%	6.1%	55.5%	0.010	Houses of birds reared on
	Y/N					the same farm as lay
						failed 28.4% later than
						houses of birds reared on
						different farm.
	Sum	-1.7%	-8.1%	5.2%	0.62

E-mail: br.poultsci@bbsrc.ac.uk URL: http://mc.manuscriptcentral.com/cbps British Poultry Science

The effect of various management systems and husbandry practices are shown in

appear to pose a risk.. Freire et al. (1999) found that, in modified cages, increased

feather pecking was associated with lower feed troughs (6 cm above ground)

compared to 28 cm.. They suggested that this was because hens stepped on each

FOSSUM, O., JANSSEN, D.S., ETTERLIN, P.E. et al (2009) Causes of mortality in

for welfare. World's Poultry Science Journal, 51: 51-61.

ARENDONK, J.A.M. (2008)b. Selection method and early-life history affect

behavioural development, feather pecking and cannibalism in layiung hens: a

review. Applied Animal Behaviour Science, 110: 217-228.

Acknowledgements 374

We thank DEFRA for funding this research (Contract no. AW 1134), and also thank 375 Noble Foods Ltd, Stonegate and farmers for providing facilities which we were 376 permitted to visit. 377