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EAAP -69 th Annual Meeting, Dubrovnik 2018 Session 42 Theatre 12

Session 42 Theatre 11

Structured antedependence model for longitudinal analysis of social effects on ADG in rabbits I. David 1 , J.P. Sanchez 2 and M. Piles 2 1 GenPhySE, Université de Toulouse, INRA, ENVT, Chemin de borde rouge, 31326 Castanet tolosan, France, 2 IRTA, Torre Marimon s/n, 08140 Caldes de Montbui, Barcelona, Spain; ingrid.david@inra.fr Even if there are evidences that the intensity of social interactions between partners vary with time, very few genetic studies have investigated how social genetic effects (SGEs) vary over time. To overcome this issue, the objectives of the present study were to analyse longitudinal records of average daily gain (ADG) in rabbits and to evaluate, by simulation, the response to selection for such longitudinal trait. Five weekly ADG records from 3,096 rabbits under feed restriction after weaning and raised in pen of 8 were used for the analysis. A linear animal mixed model including SGEs with week specific random effects that follow structured antedependence (SAD) functions was fitted to the data using ASReml and the Fortran program that we have developed (freely available on zenodo). The social heritability was higher in week 1 (0.44) than in weeks 2 to 5 (ranging from 0.16 to 0.23). The correlation between the SGEs of different weeks was moderate to high for weeks 2 to 5 (0.62 to 0.91) and weaker between the first week and the other weeks (0.33 to 0.47). The direct-social genetic correlations were negative at any time. Based on the same data design, the same variance components but considering 3 different sets of direct-social genetic antagonism (strong, moderate, weak); we simulated 7 generations of selection using a SAD model including SGEs or not to estimate breeding values. Results obtained showed that the increase in ADG with selection decreased with the direct-social genetic antagonism and was improved (~by 30%) when SGEs were taken into account. In conclusion, results confirmed that SGEs vary over time and do not correspond to the same trait after mixing than later in life, probably as a consequence of social hierarchy establishment observed at that time. Accounting for SGEs in the selection criterion maximizes the genetic progress. Piglet mortality is an important factor in pig production. Nevertheless, its statistical analysis presents serious difficulties because of its categorical nature. In recent studies, it has been suggested that the most appropriate model is a binomial model that modelled the survival of each specific piglet with a logit approach. In this study, we applied a population specific recursive binomial model to obtain estimates of the Dickerson crossbreeding parameters in a diallel cross between three strains of Iberian pigs (Entrepelado; EE, Torbiscal; TT and Retinto; RR). A total of 18,193 records from 3,800 sows distributed as follows: EE (2,843 records, 707 sows), ER (2,336,527), ET (942,177), RE (806,196), RR (4,472,874), RT (2,450,488), TE (193,36), TR (1,993,359) and TT (2,158,452). The average litter size (total number born) and stillbirth were 8.292±2.284 and 0.285±0.787, respectively. In addition, we used a pedigree of 4,609 individuals to analyse these data with a Bayesian approach through a Gibbs Sampler.

The recursive relationship between litter size and pig mortality was clearly non-linear for all crosses. The results were examined at 5, 8, 11 and 14 piglets as reference points and they indicate that the direct line effect of the EE population is higher that RR and TT with posterior probabilities over 0.97 at all reference points. Nevertheless, we were not able to detect any relevant differences between maternal effects and only the heterosis effect between TT and RR was clearly positive with posterior probabilities over 0.97 at all reference points. The main advantage of the proposed model is that allows to calculate crossbreeding parameters (line, maternal and heterosis) conditioned to each specific litter size taking into account the population specific non-linear relationships with piglet mortality and litter size.

Recursive binomial model to analyse piglet survival in a diallel cross between Iberian pigs

  L. Varona 1 , J.L. Noguera 2 , J. Casellas 3 , J.P. Rosas 4 and N. Ibañez-Escriche 5 1 Universidad de Zaragoza, Departamento de Anatomía, Embriología y Genética, 50013 Zaragoza, Spain, 2 IRTA, Genetica i Millora Animal, 25198 Lleida, Spain, 3 Universitat Autónoma de Barcelona, Departament de Ciència Animal i delsAliments, 08193 Bellaterra, Spain, 4 INGA FOOD S.A., Programa de Mejora Genética CASTUA, 06200 Almendralejo, Spain, 5 Universitat Politècnicade Valencia, Departamento de Ciencia Animal, 46071 Valencia, Spain; lvarona@unizar.es


Mobilizing tropical plants as a sustainable alternative to the issue of anthelmintic resistance in small ruminants

Keywords: Condensed tannins, Gastrointestinal nematode, Haemonchus contortus, Anthelmintic resistance

In Guadeloupe (FWI) breeders of small ruminants have to face with gastro-intestinal nematode (GIN) resistance against synthetic anthelmintics, a worldwide problem which led to high production losses. The INRA URZ specific integrated method for humid tropics to control GINs, includes the use of anthelmintic plants. At least 71 plants were found to be available in Guadeloupe to treat worms in animals. Among these plants, some contain condensed tannins (CT) that are bio-reactive complex plant secondary metabolites. Protein-CT interaction could result in affection of ruminal fermentation, allow availability of amino-acids and induce a gastrointestinal nematicidal action in ruminants.

The results indicate that CTs can be used to control anthelmintic resistant parasites (EC50 from 1.36E-6 to 1mg.mL-1), but with varying efficiencies (9 to 100% efficacy) and decreasing with the multi-resistance of the strain (-44% efficiency between the most resistant strain and the most sensitive to CT). This variability may be related to the structural complexity of the condensed tannins, the presence of other active compounds in the plant extracts, but also to the nature of the parasite resistance, which could affect the tannin-protein interactions.

A preliminary study was conducted in order to evaluate in vitro the effect of several CT types, against various chemical-resistant strains of the parasite Haemonchus contortus. CT from 8 plant species from 6 botanical families, were first extracted using acetone/water (3:7; v/v) and analyzed by LC-MS for CT content, polymerisation degree, procyanidin/prodelphinidin and free flavanol determination. CT extracts were assayed in vitro for their bioactivity against the larval exsheathment of the infective L3 stage of 5 various chemical-resistant strains of the parasite Haemonchus contortus, using up to 5 concentrations and 3 repetitions with Phosphate Buffer Sample (PBS) as control.