Effect of short-term grain feeding on bovine body-fat colour: a cautionary note

Abstract

Seventeen Brahman steers were removed from pasture and fed a high grain diet for 8 weeks prior to slaughter. Carotenoid concentrations were determined in samples of serum and subcutaneous fat obtained either from live animals or at slaughter. At slaughter carcass fat colour was assessed according to AUS-MEAT specification. The concentrations of G-carotene in the serum of these animals fell rapidly (over 60%, P lt; 0.001) in the first 2 weeks on the grain diet and then plateaued. There was no change in either the concentrations of carotenoids in subcutaneous fat or in fat colour of these cattle during the whole period of grain feeding. The overall average liveweight gain was 0.59 kg/day. Failure to observe changes in concentrations of carotenoids was unexpected, and may be partly due to the fact that these cattle did not settle to the trial conditions in the feedlot, as indicated by the significantly higher cortisol concentration in their serum compared with the initial slaughter group. The implications of the outcome of this study are discussed.