Interaction of protein supplementation and ecotype on growth performance and carcass traits of Nguni goats

Abstract

Nguni goats are thought not to respond to dietary protein supplementation. The objective of the study was to determine the interaction of protein supplementation and ecotype on growth performance and carcass traits of Nongoma, Msinga and Cedara Nguni goat ecotypes. Thirty-six five-month-old castrated males were randomly allotted to a 3 × 3 factorial design experiment and provided 0, 150 and 300 g protein concentrate per day. There was an interaction of ecotype and protein supplementation on average daily gain (ADG). The ADG of the Nongoma and Cedara goats increased with protein supplementation, but the Msinga ecotype was not affected by the treatments. Goats of the Cedara ecotype weighed 34.4 kg when provided 300 g of supplement, whereas the Nongoma ecotype weighed 26.5 kg at slaughter when unsupplemented. The dressing percentage did not differ with the level of protein supplementation or ecotype. From the fifth quarter, the skin was affected by ecotype, gut fill by protein supplementation and the weight of the head by both factors. The Cedara ecotype had a heavier fifth quarter at 300 g supplementation. There was no interaction of protein supplementation and ecotype on dissectible fat. Intestine and visceral fats were affected by protein supplementation, whereas stomach fat was affected by ecotype.