Interactions in postweaning production of F-1 cattle from Hereford, Limousin, or Piedmontese sires

A 2-yr study was conducted to evaluate the interactions of castration, feed ing length, and dietary CP on growth and carcass characteristics of male ca ttle (bulls and steers) that vary in expression of muscular hypertrophy. Cr ossbred cows were bred by Al to Hereford, Limousin, or Piedmontese bulls, w hich represented genotypes with normal, moderate, and hyper-muscularity, re spectively, but with similar mature weights. Male calves (131 in yr 1 and 1 20 in yr 2) were placed in pens with individual electronic feeding gates. C alves were fed growing diets until they reached 386 kg BW and then were ind ividually switched to finishing diets for 90 or 132 d. Interactions were ob served among sire breed, gender, and feeding length on carcass composition. Bulls were more efficient than steers in producing live weight gain. Lengt h of finishing period accounted for a larger source of variation than gende r for weight characteristics, whereas gender was the larger source of varia tion for carcass composition. Concentration or degradability of dietary CP influenced rate of gain from weaning to 386 kg. Interactions resulting from varying management on carcass characteristics among calves of different si re breeds indicate that unique strategies may be beneficial for the product ion of meat from these breeds.