Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 18 THE PRODUCTION EFFICIENCY OF CATTLE OF DIFFERENT BREED AND MATURE LIVEWEIGHT A.Z. CUTHBERTSON*, M.P. DELAND** and B.D. SIEBERT* Deland et al. (1990) have shown that crossing Hereford (H) cows with Jersey (J) or Simmental (S) sires then crossing the female progeny with a Charolais (C) terminal sire significantly increases (15%) the weaning weight of calves in comparison to those from a straight bred Hereford system. The efficiency of such a system however, relies not only on the weight of animal, but also on the quantity of forage consumed by the cow and calf. Although related to weight, feed consumption varies with milk yield and body composition (Hunter and Siebert 1986) and needs to be measured to determine the efficiency of various breeding systems. For this reason, we measured growth and voluntary feed consumption (VFC) in the breeds mentioned above. The latter was achieved by the use of slow release chromic oxide capsules (Captec Pty Ltd, Laverton, Vic). They were used in cows at two stocking rates on four occasions during the year and in calves after they reached 6 months of age. Feed consumption reached a maximum in late spring, when at 1.0 cow/ha it reached 11.16, 9.74 and 10.08 kg/d for the HxB, Cx(JxH) and Cx(SxH) respectively. At 1.2 cows/ha, the values were 7.72, 7.83 and 8.13 kg/d, Jersey crossbred weighed less and their intake per unit live weight was some two units greater than the other breeds at both stocking rates. The efficiency of production, expressed as the weight of calf produced per unit of feed consumed by the cow over the year and the calf after six months of age, is shown in Table 1. Table 1 The efficiency of production of calves from three breeds of cattle held at two stocking rates (SR) + Mean voluntary feed consumption over a period of 222 d Cows of all breeds consumed more feed but calf growth was less efficient at the lower stocking rate. Significantly higher live weights were achieved at the lower stocking rate, but at both rates the crossbred cattle weighed more-the Simmental cross being the largest at 1.0 cow/ha. At the higher stocking rate however, this advantage was lost. In both cases, the Jersey cross was more efficient in terms of calf produced per unit of feed consumed, demonstrating the advantage of small maternal size. DELAND, M-P., ROWE, J-P. and BOURNE, L. (1990). Proc. 6th Conf. A.A.A.B.G. (in -press). HUNTER, R.A. and SIEBERT, B-D. (1986). Aust. J. Agric. Res. 37: 549. * CSIRO Division of Human Nutrition, O'Halloran Hill, S.A. 5158. ** Struan Research centre, P-0. Box 618, Naracoorte, S.A. 5271. 467