Intake, live animal scores/measurements and carcass composition and value of late-maturing beef and dairy breeds

Abstract

The objectives of this study were to compare the progeny of 1) late-maturing beef with dairy breeds and 2) Charolais (CH), Limousin (LM), Simmental (SM) and Belgian Blue (BB) sires bred to beef suckler dams, for feed intake, blood hormones and metabolites, live animal measurements, carcass traits and carcass value in bull and steer production systems. The bull system included 50 late-maturing beef breeds and 22 Holsteins (HO) slaughtered at approximately 15 months of age, whereas the steer system consisted of 56 late-maturing beef breeds and 23 British Friesians (FR) slaughtered at approximately 24 months of age. Beef breeds were suckled until approximately 8 months of age, while dairy breeds were artificially reared until weaning at approximately 3 months of age. All animals were finished on an ad libitum concentrate diet. Mean live weight, live weight gain, carcass gain and feed efficiency were greater ( P < 0.05) in beef than dairy breeds in both systems during the finishing period when offered concentrates. Although there was no difference in feed intake between beef and dairy breeds, intake expressed relative to live weight was lower ( P < 0.001) in beef breeds in both systems. At 10 months of age and pre-slaughter, beef breeds had higher ( P < 0.001) muscularity scores and greater scanned muscle depth ( P < 0.001) than their dairy contemporaries. Carcass weight, kill-out proportion, carcass conformation score, meat proportion and value were greater ( P < 0.001) and carcass fat and bone proportions were lower ( P < 0.05) in beef than dairy breeds in both systems. Insulin concentrations were lower ( P < 0.001) in beef than dairy breeds, whereas there was no difference in blood metabolites or IGF-1 concentrations. Feed intake expressed relative to live weight or feed efficiency did not differ between CH, LM, SM or BB sired progeny. Muscularity scores were greater ( P < 0.05) in BB than SM, whereas skeletal scores were lower ( P < 0.05) in LM than SM. Limousin had lower ( P < 0.05) carcass gain per day of age than CH and SM, whereas SM had a lower ( P < 0.05) carcass conformation score than BB and CH and a higher ( P < 0.05) carcass fat score than CH. Simmental had a lower ( P < 0.05) carcass meat proportion and a higher ( P < 0.05) carcass fat proportion than CH, LM and BB, which were similar ( P > 0.05). The improvement obtained for beef over dairy breeds in live weight gain was 12%, while the improvements in carcass gain and meat produced was 24% and 33%, respectively. This demonstrates that the importance of carcass data contributing to breed comparison studies cannot be over-emphasised.