Investigation Into The Precision Feeding Of Nguni Steers Under Feedlot Conditions

Abstract

The purpose of the project was to assist the Nguni Cattle Breeders’ Society to determine the most suitable ration for Nguni calves under feedlot conditions, and to investigate which animals will perform best under feedlot conditions. The rations that were evaluated were: Nguni Starter (High roughage), Nguni Grower (Medium roughage), Nguni Finisher (Low roughage) and Feedlot Grower Commercial (Low roughage). The trial was run at Sernick feedlot, near Edenville. Two hundred Nguni male calves, sourced from 24 different herds from five provinces, were divided into four groups of 50 each. They were backgrounded in the pre-conditioning phase for 32 days and received ad lib Eragrostis grass. They were randomly allocated to, and tested on four different rations, viz and slaughtered when they reached acceptable carcass subcutaneous fat classification, either after 105, 120 or 135 days on test. Animals with the highest initial weights were slaughtered first (105 days on feed and had the highest end- and carcass weights). None of the other slaughter groups were able to match these end and carcass weights, irrespective of the rations received. Calves on the commercial ration did significantly better than the calves on the other rations for ADG (1.34 kg/d vs 1.24-1.27 kg/d), total gain (159.1 kg vs 147-150 kg), end weight (7 to 11 kg heavier) and had a carcass weight of 204 kg vs. 196-198 kg for the other treatment groups. Dressing percentage of animals on the commercial ration was 56.5%, which was not significantly better (P >0.05) than the dressing percentage of the high (roughage) ration animals. Significant differences in starting weight and age were evident in calves originating from different provinces, but these differences were not significant at the end of the test with regards to carcass traits, as animals were not slaughtered on the same day. Arrival weight had a marked influence on test length and margin over feed costs, favouring the heavier calves. Carcase weights of calves with higher arrival weights were also heavier and closer to market requirements. It was concluded that Nguni cattle can be fed profitable in feedlots. Results indicate that preconditioning calves to reach minimum weights close to 200 kg to be considered on arrival (or at the end of preconditioning or backgrounding phase) for profitable feeding of Nguni cattle in a feedlot. Although ration had a significant effect on ADG, it was negated by other factors contributing to differences in feedlot profitability. Although the low roughage and commercial rations were not the cheapest per ton, they were the most profitable to feed in this case. Nguni cattle did also perform profitably on the (normal) commercial diet. Significant differences in feedlot performance could be attributed to the source of animals. Individual herds were obviously restricted to region or province. Although not necessarily proven by this trial, these differences may be due to genetic merit, or environmental conditions prior to the trial. No excessive health fallouts occurred.