Effects of various proportions of wheat, bran or pollard in sorghum grain fattening diets on liveweight gain, feed efficiency and carcase composition of Hereford and Hereford × Santa Gertrudis cattle

Abstract

A 3 x 2 x 2 factorial design was used to examine the wheat by-products pollard and bran as a replacement in all-sorghum grain feedlot diets. The by-products replaced either 10, 30 or 50 per cent of the sorghum. Fourteen groups each of five Hereford steers of a mean initial shrunk liveweight of 251.5 ¦ S.E. 0.16 kg and seven groups each of five Santa Gertrudis x Hereford cross bullocks of 391.7 ¦ 0.16 kg were used. They were slaughtered at a mean final shrunk liveweight of 407.0 ¦ 3.54 and 534.5 ¦ 5.04 kg respectively. Production results from cattle receiving 50 per cent by-products were significantly inferior to lower levels of by-product. There were no significant differences between 10 and 30 per cent by-product. Cattle receiving pollard performed significantly better than those receiving bran. The growth rate of the Hereford steers of 1.24 kg day-1 was inferior (P < 0.01 ) to that of 1.41 for the Santa Gertrudis x Hereford bullocks, but the estimated gain in carcase weight of 0.75 kg day-1 was the same. The feed conversion ratio per unit of carcase weight gain favoured the Hereford steers (9.91 vs. 11.95; P < 0.01), but the feed conversion ratio per unit of liveweight gain was not significantly different (6.29 vs. 6.06). The total body fat figures were comparable for steers and bullocks -(mean 20.4 per cent). Both the percentage total yield of saleable meat and the percentage yield from the hindquarter were significantly greater (P < 0.01) in the Santa Gertrudis x Hereford cross bullocks (71.4 vs. 69.5 and 36.8 vs. 35.5 respectively).