Abstract
Management of beef suckler cattle herds requires a difficult but vitally important balance between farm profits,
animal health and welfare and sustainable food production. A dynamic programming (DP) model was implemented
to investigate the consequences of replacement and management decisions on the interactions and possible
trade-offs between animal welfare, fertility and profitability in breeding beef suckler cattle herds. The model maximized
profit from the current cow and all successors by identifying the best keep/replace decision. The 150 states
incorporated in the DP model were all combinations of: ten cow-parity, five calving periods including one barren
state (five in total) as fertility indicators and three body condition scores at weaning as an animal welfare indicator
reflecting feeding and nutritional conditions of animals. Statistical models were fitted to data from a breeding
suckler cattle herd, consisting of performance records of 200 cattle over 5 years, to parameterize the DP
model. Estimated parameters used in the DP model were: (i) probabilities of transitions between states and (ii)
probability of involuntary culling. These estimates were used in the form of conditional probabilities of successful
or failed (as a result of involuntary culling) transitions to the next state. In addition, statistical models were used to
estimate probability of calving difficulty. There was strong evidence (P < 0.001) that parity affected calving difficulty
and weak evidence (P = 0.067) that parity affected the incidence of involuntary culling. The DP model outcomes
indicated that cows calving very early, i.e. those who conceived in the first 21 days after artificial
insemination, showed reduced frequencies of calving difficulty as well as voluntary culling, and so gave
better financial returns than late-calving cows and barren cows. As a result, fewer replacements were needed
that reduced the frequency of calving difficulty, further implying a win-win scenario for both profit and
welfare. In contrast, in late-calving animals, the frequency of calving difficulty increased and they were less profitable
and more prone to be culled. Results of sensitivity analysis showed that the optimum voluntary culling rate
was sensitive to commodity market prices. These findings suggest well-informed nutrition and reproduction management
could deliver a win-win outcome for profit and animal welfare.
Year
2017
Category
Refereed journal