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 rel ation to liveweight (LW) and growth rate, was investigated using data from 540 progeny of 154 British Hereford sires, collected over ten 200-day postw eaning performance tests conducted between 1979 and 1988. Residual feed int ake (RFIReg) was calculated for each test as the difference between actual feed and expected feed intake predicted from a multiple regression of feed intake on metabolic mid-test LW and average daily gain (ADG). RFIReg was he ritable (0.16, S.E. 0.08) and phenotypically and genetically independent of size and growth rate. RFIReg had favourable phenotypic and genetic correla tions with feed conversion ratio (FCR) and estimated maintenance energy exp enditure. It was negatively correlated with estimated lean content of the c arcase (LEAN) and appeared to be genetically independent of mature cow LW ( COWWT). RFIReg over the performance test was not affected by differences in pre-test rearing treatments, in contrast to start-of-test LW and end-of-te st LW, and in some years, ADG and FCR. Selection against RFI has the potent ial to increase the efficiency of beef production by reducing feed intake w ithout changing the growth rate of the young animal, or increasing mature c ow size. (C) 2000 Elsevier Science B.V. All rights reserved.