EFFECT OF MORTALITY-RATE, BREED TYPE AND BREED ON TOTAL HERD EFFICIENCY

The influence of two scenarios of mortality rates (assumed average and observed) on total herd efficiency of the four main breed types in So uth Africa (Sanga/Zebu, composite, British and European), as well as a ll the individual breeds participating in the National Beef Performanc e Testing Scheme (1980-1985), was investigated by means of a computer simulation program. Simulation runs were done for an 18/18 month produ ction system (all market animals sold at 18 months of age) in the case of the evaluation df breed types and for an 8/18 month (steers sold a t eight months of age I surplus heifers sold at 18 months of age), as well as an 18/18 month production system in the case of the evaluation of the individual breeds. Mortality rate had a marked influence on ra nking of breed types as well as individual breeds in terms of relative income per hectare. Composite breed types normally performed well, in dicating that use of such breeds in a variety of environments is a goo d choice. This study also indicated that bio-diversity does exist betw een breeds and further research is needed on breed characterization, s ince no framework currently exists for the characterization of breeds for bio-economic important traits.