60th EAAP Congress – Barcelona 24-27 August 2009

L. Puillet – O. Martin – D. Sauvant – M. Tichit

Integrating feeding and reproductive management of dairy goats :

a modelling approach to assess herd performance

RationaleIncreasing need to find compromise between

production level and herd efficiency

A model integrating management x individual variability

DM MY

Productive life

Management

∆

Variability

Model presentation

Goati

Group HerdBiologicalsystem

Decisionalsystem

MY, lactation number, physio. state

Diet change, culling, mating

IF [condition true] THEN [action]

Farmer’s Project

Reproduction ReplacementFeeding

Strategy input parameters

Simulation method2 x 2 factorial design:

- Reproductive management strategiescondensed vs spread mating

- Feeding management strategies2-step vs 5-step feeding sequences

Herd (300 goats + 90 does) mated in season

0

0.4

0.8

1.2

1.6

0 100 200 300

Con

cent

rate

DM

(kg/

d)

Lactation time (days)

5 steps2 steps

Simulation method

20 years simulated

10 years analyzed

15 replications

Genetic potential

Managementparameters

***

*Puillet et al., An individual based model to simulate individual variability and herd performance in the long term, in preparation**

Puillet et al., 2008. Simple representation of physiological regulations in a model of lactating female: application to the dairy goat. Animal 2, 235-246

Virtual herd

Goats

Herd

Results

• (1) Overview

• Focus on condensed mating

• (2) Herd

• (3) Productive life

• (4) Individual variation in BW

(1) Overview

Cond_2stepsCond_5steps

Spread_2stepsSpread_5steps

0

100

200

300

0

500

1000

1500

2000

10/11/2002 10/11/2003 09/11/2004 09/11/2005 09/11/2006

Nb of lactatinggoats

Herd MY (kg/15d)

(2) Herd

2 steps 5 steps

↑ number of steps Slight production level ↑

240000

242500

245000

247500

MY (kg)

0.18

0.181

0.182

0.183

0.184

0.185

1 22 steps 5 steps

But ↑ number of steps Slight production cost ↑

Efficiency ↓

Feed cost(€/kg of milk)

ReproGrpFeedSeqLow ReproGrp FeedSeqHigh

3.0

3.5

2.5

0.16 0.18 0.20 0.16 0.18 0.20

(3) Productive lifeWhere are the goats?Nb of

goats

Ave

rage

lifet

ime

MY

(kg/

d)

Average lifetime feed cost(€/kg of milk)

2 steps n=4553 5 steps n=4601

Average lifetime feed cost(€ /kg of milk)

0 11-15 26-30

1-5 16-20 31-35

6-10 21-25 >35

ReproGrpFeedSeqLow ReproGrp FeedSeqHigh

700

1000

4500.0 12.5-12.5

(4) Individual variation in BW

2 steps n=4084 5 steps n=4128

0.0 12.5-12.5

MY

(kg)

ove

r2d

lact

atio

n

BW difference (kg) actual-potential at 90d of 2d lactation

BW difference (kg) actual-potential at 90d of 2d lactation

+ 20%

Nb of goats

GainLoss

0 6-8 16-20

1-2 9-11 21-30

3-5 12-15 >30

Conclusion

Feeding sequences ≈ effect at herd and productive life levels

Efficiency

≠ biological processes

2 steps sequence =

↑ % individuals losing BW

Indiv. variability biological buffering abilities

LFS adaptability

Model investigation tool

Management effect on individual variability

- Feeding level and genetic potential

- Management simplification linked to labor constraint in large herds

Perspective

Service advisers of Poitou-Charentes for their contribution to management model development

UMR INRA PNA and SAD-APT staff

Financial support from:

• INRA PHASE & SAD

• French région Poitou-Charentes

Acknowledgment

Laurence.Puillet@agroparistech.fr