The influence of pre-weaning nutrition on biochemical and myofibre characteristics of bovine semitendinosus muscle

This study investigates pre-weaning growth of cattle and its effect on bioc hemical and histochemical markers of muscle development and subsequent biop hysical attributes of eating quality. Combinations of cow (late pregnancy t o mid-lactation) and pre-weaning (varying duration of access to a high-ener gy ration) supplementation were used to vary calf growth to weaning in 6 tr eatment groups. After weaning, calves were grazed together on pasture (back grounding) and then grown rapidly on a feedlot ration (finishing) until sla ughter. Biochemical and myofibre characteristics were determined in semiten dinosus muscle samples collected just prior to weaning (7 months), at the e nd of backgrounding (13 months), and at slaughter (17 months). The concentr ation of sarcoplasmic protein and the activity of lactate dehydrogenase in the muscle at weaning were associated with differences in pre-weaning growt h and both variables correlated positively with liveweight at weaning. Isoc itrate dehydrogenase activity varied with sex, not treatment, at weaning an d at the end of backgrounding. The size of myofibres at weaning related to differences in growth path and correlated positively with liveweight. Pre-w eaning growth effects on these characteristics were not evident at slaughte r. Biophysical properties of the meat were not affected by earlier growth p ath treatment, and were not correlated with biochemical characteristics or myofibre type profile. Variation in both shear peak force and adhesion was related to sex. We conclude that the effects of divergent early life growth do not persist 10 months after weaning, at least in meat quality character istics.