Optimal management of relplacement heifers in a beef herd: A model for simultaneous optimization of rearing and breeding decisions A.H. Stygar, A.R. Kristensen, J. Makulska Katarina Nielsen Dominiak Ph.D. student Department of Large Animal Sciences
AQMHM 2016 Markov 05/10/2016 2 Decisions Strategy - Cost optimization - Production optimization Long term planning
AQMHM 2016 Markov 05/10/2016 3 Multi Level Hierarchic Markov Process - MLHMP Founder level 0 Total heifer rearing period Birth Successful conception Child level 1 Days 30,5 30,5 30,5 30,5 30,5 30,5 30,5 30,5 30,5 0 Preweaning period – 10 stages Birth 9 mo Child level 2 Days 1-10 mo 21 21 21 21 21 21 Reproductive period – 32 cycles Weaning Puberty
AQMHM 2016 Markov 05/10/2016 4 Multi Level Hierarchic Markov Process - MLHMP Total heifer Founder level 0 rearing period Birth Successful conception One state variable: Birth month Indoor season: November – April Outdoor season: May – October Decision: Feeding level until puberty defined by Average Daily Gain (ADG) Information: Month of age-depending stages in child levels, feeding costs, breeding costs
AQMHM 2016 Markov 05/10/2016 5 Multi Level Hierarchic Markov Process - MLHMP Child level 1 Preweaning period 10 stages Days 30,5 30,5 30,5 30,5 30,5 30,5 30,5 30,5 30,5 0 Birth 9 mo 10 stages: Months suckling at cow (1-9) Stage length: 30,5 days State variable: Body weight (BW) in classes of 10 kg Decisions for each stage: Wean or continue suckling period Strategies: If weaned; ADG in reproductive period is chosen 400 g, 600 g, or 800 g
AQMHM 2016 Markov 05/10/2016 6 Multi Level Hierarchic Markov Process - MLHMP Reproductive period – 32 cycles Child level 2 Days 1-10 mo 21 21 21 21 21 21 Weaning Puberty 33 Stages: 1 ‘weaned’ + 32 reproduction stages Weaned stage Reproduction stages Length: 1-10 months Length: 21 days each State variable: BW class State variables: BW class and reproductive status Decision: ‘Continue feeding’ Decisions: - Estrus: ‘keep’ or ‘breed’ - Nonestrus: ‘keep’ or ‘replace’ - Pregnant: ‘wait for calving’ - Diseased: ‘replace’
AQMHM 2016 Markov 05/10/2016 7 Feed costs 70-80 % Calf reared - without mother + milk replacement + fourage feed (ADG 800 g) - without mother + milk replacement + concentrate supplement (ADG 1000 g) - by mother + fourage feed (ADG 800 g) - by mother + concentrate supplement (ADG 1000 g) - by mother + concentrate supplement indoor (ADG 1000 g) Heifer in reproductive period - Outdoor (ADG 400 g) - Outdoor (ADG 600 g) - Outdoor (ADG 800 g) - Indoor (ADG 400 g) - Indoor (ADG 600 g) - Indoor (ADG 800 g)
AQMHM 2016 Markov 05/10/2016 8 Non - feed costs 20-30 % Breeding costs Slaughter price Buying pregnant heifer
AQMHM 2016 Markov 05/10/2016 9 All costs are related to the birth month
AQMHM 2016 Markov 05/10/2016 10 Revenue PFP: Predicted Future Productivity Data from 2.758 heifers used to estimate PFP Relationship between PFP and Costs are influenced by season Age BW Age and BW at conception are Season of conception significant predictors of PFP
AQMHM 2016 Markov 05/10/2016 11 Net return – making a decision = expected reward Weaning Breeding = cost of calf by mother Replacing = feed cost = stage Optimal strategy = preweaning state = reproductive state
AQMHM 2016 Markov 05/10/2016 12 Results – net return Highest Lowest Average EUR 339.3 EUR 267.9 Birth month May August Weaning age 9 months 9 months Baseline Weaning month February May ADG 800 g 800 g 810 g (pre puberty) ADG 800 g 400 g 810 g (reproductive) Age 12.8 18 13.2 (conception) months months months BW 54.2 % 61 % 55.6 % (conception) of mature of mature of mature
AQMHM 2016 Markov 05/10/2016 13 Historical data 1991 - 2008
Short and high growth rate Longer and slower growth rate Conception summer time Conception winter time Net return Net return 18 % up 6.5 % down Plan your production
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