Abstract
This paper presents a procedure for the development of a breeding objective for a beef cattle breed used in a range of production systems. The five main beef cattle production systems in France were first described and then equations of income and costs as a function of the 25 biological traits to be genetically improved for breeding and production were established. Economic values for individual systems were defined as the first derivative of the herd profit with respect to these 25 traits while the economic values for the overall breeding objective were taken as the average of economic values over the five production systems. An application is presented for the Limousin breed. Sensitivity of the breeding objective to variation in the economic or demographic context was also studied. Breeding traits, especially maternal effects on weaning weight and calving success, were identified as the most economically important traits requiring improvement. Relative economic values were very robust with respect to variations in system frequencies and replacement rates. A dramatic change in the market price for beef (−50%) increased the relative weighting of carcass quality traits to the detriment of breeding traits although a smaller change in beef price (−25%) had no significant effect on the relative economic values.
Keywords
Beef cattle; Production system; Breeding objective; Sensitivity analysis