integrating feeding and reproductive management of...
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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
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