Genetic variation in residual feed intake and its association with other production traits in British Hereford cattle

Variation in residual feed intake, that is, variation in feed intake in relation to liveweight (LW) and growth rate, was investigated using data from 540 progeny of 154 British Hereford sires, collected over ten 200-day postweaning performance tests conducted between 1979 and 1988. Residual feed intake (RFI ) was calculated for each test as the difference between Reg actual feed and expected feed intake predicted from a multiple regression of feed intake on metabolic mid-test LW and average daily gain (ADG). RFI was heritable (0.16, S.E. 0.08) and phenotypically and genetically independent of size and Reg growth rate. RFI had favourable phenotypic and genetic correlations with feed conversion ratio (FCR) and estimated Reg maintenance energy expenditure. It was negatively correlated with estimated lean content of the carcase (LEAN) and appeared to be genetically independent of mature cow LW (COWWT). RFI over the performance test was not affected by Reg differences in pre-test rearing treatments, in contrast to start-of-test LW and end-of-test LW, and in some years, ADG and FCR. Selection against RFI has the potential to increase the efficiency of beef production by reducing feed intake without changing the growth rate of the young animal, or increasing mature cow size.  2000 Elsevier Science B.V. All rights