Efficiency of weight gain of serial slaughtered bulls of a five-breed diallel.

Weight and feed consumption of 197 bulls were recorded monthly in a serial slaughter experiment continuing over a period of 24 mo. The bulls were produced in a modified five-breed diallel of the Angus, Brahman, Hereford, Holstein and Jersey breeds. Our objective was to estimate efficiency of feed conversion for weight gain for each breed and cross. The model included average weight gain per day (ADG) as a dependent variable; independent variables included breed-type, season, month within season, average feed intake per day (ADI), initial weight, weight to the .75 power, breed x ADI and season x ADI effects. The sum of the partial regression coefficients of ADG on ADI and on breed x ADI adjusted for season, month within season, initial weight, weight to the .75 power and season x ADI was interpreted to be an estimate of intrinsic or net efficiency of ADG. There were no significant differences among the various breed-types in intrinsic efficiency of ADG. Average heterosis for intrinsic efficiency of feed conversion was not significant. None of the contrasts among breed-types was significant for intrinsic efficiency of ADG (British vs dairy, 1.1 +/- 12.3 g/d; Brahman-dairy crosses vs British-dairy crosses, 32.7 +/- 12.9 g/d; British-Brahman crosses vs British-dairy crosses, 13.9 +/- 12.4 g/d; British-Brahman crosses vs straightbred British 3.2 +/- 14.8 g/d).