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Improved animal and plant production was one of the greatest achievements of the last century and was mainly achieved through genetic selection. Phase C tests are the only performance tests that evaluates both the performance in growth rate (ADG) as well as the efficiency with which animals utilize feed (FCR) on an individual basis. Selection based on Phase C testing can therefore play an important role in genetic improvement of animals fed under feedlot conditions. Since 75% of the beef in South Africa is finished in feedlots genetic improvement could be of great importance to the beef industry. Two regressions were run to explore whether Phase C testing (genetic selection) affect the FCR and ADG over time. Following the regression, the effect of genetic selection on feedlot profitability was investigated. This was done by entering the average ADG and average FCR for the group of bulls fed per year into a feedlot model that calculated the profit when feeding cattle under different scenarios. It was found that genetic selection enabled improvement in FCR up to a certain stage, but this improvement also reached a peak. The regressions could not confirm that the change in ADG is caused by genetic selection. One explanation for this result could be that other variables that are not represented in the explanatory variable have an effect on the ADG, such as the temperament of the animals, stress, housing conditions of animals and production conditions. The feedlot model showed that by genetically selecting top performing bulls, one will not only prevent a loss but also increase the profit when feeding cattle. It was also seen that FCR has a much bigger influence on the feedlot profit than ADG.

Keywords: Feed conversion ratio; average daily gain; feedlot; profit.

South Africa

Author(s): Lombard W.A. (1), Maré F.A. ( 1)

Organization(s): University of the Free State (1)