Philippe Faverdin

Christine Baratte

Romain Perbost

Sylvain Thomas

Eric Ramat

Luc Delaby

Jean-Louis Peyraud

J-L Peyraud

Dynamic herd simulations

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Background and objective

 At cow level, on a daily basis:

 N efficiency in dairy cows depends of the rumen balance of nitrogen and the efficiency of metabolizable protein (MP)

 MP efficiency if a function of MP/NE of the diet, energy balance, essential AA content and milk yield.

 However, what are the main factors of N efficiency at herd scale according the type of dairy system and annual feeding management ?

 CowNex, a simple tool to estimate N efficiency of a dairy herd  Merging animal sub-model and a herd demography structure (number of heifers, dry cows and productive cows across the year and the feeding strategies for each category of animals).

 The animal sub-model predicts N intake and urinary and faecal N output on a daily basis using on farm available data.

 N intake and N partition is predicted daily using the intake model developed during the GRAZEMORE project and other results of the RedNex project.

General overview of CowNex

Input Models Output (total or per feeding group) It does not necessarily reflect its view and in no way anticipates the Commission's future policy in this area.

Thank you for your attention

Plan

  Description of the modeling work  Presentation of the CowNex Website  Simulation of different model farms with different characteristics and feeding systems Objective of CowNex: Building a model predicting N excretion for a dairy herd over the year  Calculating N excretion from a dairy herd according to the number of animals and the diets on a daily basis.

Feed(Feed

  Faverdin et al, Grass and Forage Science, 2011) Faverdin et al. RedNex Final conference Paris 30th August 2013 Faverdin et al. RedNex Final conference Paris 30th August 2013 Use of CowNex: different steps  Describe the main characteristics of the herd : Herd  Select the feedstuffs used to fed the herd during the year : Define the main groups of cattle gathering several classes of animal fed with the same diet during the year : Feeding Groups  Indicate for each feeding group the different diets offered during the year : Diet Plan  Run the simulation to get results : Simulation Faverdin et al. RedNex Final conference Paris 30th August 2013 Simulation of feeding management of different model farms using survey data Exemple of one model farm description (Institut de l'Elevage, 2011) of different model farms in different parts of France Faverdin et al. RedNex Final conference Paris 30th August 2013 A complex description of the intake: simplification with a sequence of diet kg DM/cow/d) Day of the year Faverdin et al. RedNex Final conference Paris 30th August 2013 Simulation using model farms to study N efficiency Protein selfsufficiency and emissions in different farming systems 1/ Translation of the feeding system description in CowNex to be consistent with global feed use data 2/ Simulation of the model farms and adaptation with CowNex -Effect of age at first calving -Comparison of model dairy farms -Effect of protein supplementation on several model farms

ProteinNTheNGreenhouse

  Faverdin et al. RedNex Final conference Paris 30th August 2013 Faverdin et al. RedNex Final conference Paris 30th August 2013 Faverdin et al. RedNex Final conference Paris 30th August 2013 Faverdin et al. RedNex Final conference Paris 30th August 2013 Soybean meal (kg DM/cow/y) NH 3 emission (kg/cow/y) Faverdin et al. RedNex Final conference Paris 30th August 2013 Faverdin et al. RedNex Final conference Paris 30th August 2013 Faverdin et al. RedNex Final conference Paris 30th August 2013 Conclusions  CowNex is a simple tool to assess quickly the efficiency of N use at herd level  Increase age at first calving decrease N efficiency of meat  If maize systems could theoritically better balance protein supplementation, it is not always observed in pratice and they are less protein selfsufficient  Protein supplementation is an important lever to control protein selfsufficiency, nitrogen excretion and environmental impacts of dairy farming system  Time spent indoor increases the risks of ammonia emissions  In many systems, there is economic and environmental benefit to pay attention to the protein supplementation Faverdin et al. RedNex Final conference Paris 30th August 2013 This presentation has been carried out with financial support from the Commission of the European Communities, FP7, KBB-2007-1.

Whole herd analysis : effect of age at first calving

	Example of 6 specialize dairy farms
	Variable	2 years 3 years
	Cows	100	100
	Heifers	84	133
	Calves	13	13
	Feed use (t/y)	998	1199
	Conc use (t/y)	195	203
	N intake (kg/y)	24380	29399
	N Meat (kg/y)	622	745
	N Milk (kg/y)	5109	5119
	N Efficiency %	23.7	20.0
	N milk efficiency %	27.3	27.3
	N meat efficiency %	9.9	6.3
	N Self sufficiency	70.2	73.3

 Virtual Farm with 100 cows high maize use, high producing cows (9700 kg milk) and group calving  All heifers are reared with high replacement rate  Replacement rate has little effect on N meat or milk efficiency  Farms of plain regions

Forage system West Other regions >30% ha maize Maize W Maize E 10%< ha maize<30% Maize Grass W Maize Grass E >10% ha maize Grass W Grass E

Faverdin et al. RedNex Final conference Paris 30th August 2013

Comparison

of dairy systems OTHER REGIONS WEST Annual results

	Impact of indoor protein
	supplementation on emissions
			OTHER
			REGIONS			WEST
	Annual results	Maize E Maize E	Maize Grass E Maize Grass E Grass E Maize W Grass E Maize W	Maize Grass W Maize Grass W Grass W Grass W
	Total Diet DM (kg) N Milk (kg)	7047 44.2	6756 40.6	6108 32.5	6791 42.3	6327 37.8	5732 30.4
	Total Diet N(kg) N Faeces (kg)	187 61.8	181 62.0	152 54.2	165 59.5	163 56.3	142 52.0
	CP annual diet N Urine (kg)	166 80.2	168 78.7	156 64.9	152 62.5	161 68.7	155 57.8
	Milk (kg) /cow N excreted (kg)	8169 142	7500 141	6334 119	7827 122	6786 125	5608 110
	Self sufficiency(DM) N Efficiency	76% 23.6%	82% 22.4%	89% 21.4%	87% 25.7%	88% 23.1%	94% 21.4%
	Self sufficiency(N) Kg NH3/T milk	49% 4.9	57% 4.0	78% 1.8	67% 2.2	73% 3.4	79% 1.7
	% Controllable	69%	63%	48%	58%	56%	47%

Faverdin et al. RedNex Final conference Paris 30th August 2013

Comparison of dairy systems  Comparaison of different protein supplementations in dairy systems using large amont of soyabean meal (dairy specialized and cropdairy systems). Calcul on dairy cows only.  14% CP  15% CP  16% CP  Collection of CowNex output to calculate NH 3 and N 2 O emission using the EMEP/EEA european reference method and national database to describe housing and manure management systems

Soybean meal (kg DM/cow/y) Selsufficiency (%) Faverdin et al. RedNex Final conference Paris 30th August 2013