The utilisation of complete cereal-based diets differing in roughage inclusion level by Matabele goats and Sabi sheep

Abstract

Diet digestibility and the degradability and rate of passage of the roughage fraction were measured for four maize-based diets containing either 50 per cent (VH50), 33 per cent (VH33), 22 per cent (VH22) or 10 per cent (VH10) roughage as natural rangeland (veld) hay. Treatment diets were offered ad libitum to castrate Matabele goats (46.4 (+ or -) 1.81 kg) and Sabi sheep (49.4 (+ or -) 1.8 kg) in an incomplete paired latin square (4 diets and 3 periods). Each 32-day period comprised a 21-day adaptation period followed by a seven-day digestibility and concurrent rate of passage determination of chromium mordanted hay and four-day in sacco degradation of veld hay. Ad libitum dry matter intakes were similar (P>0.01) for both species with means of 67, 59, 59 and 50 g/kg 0.75 for diets VH50 to VH10. In vitro dry matter digestibility of the complete diets was similar (P>0.01) in goats and sheep, averaging 664, 715, 722 and 801 g/kg for diets VH50 to VH10. Potential dry matter degradability (a+b) of the veld hay fraction in the diet was similar (P>0.10) for both species and averaged 639, 615, 540 and 438 g/kg DM for diets VH50 to VH10, respectively. Mean retention time of chromium mordanted veld hay was 88.2 and 65.3 hours (P<0.001) for goats and sheep, respectively, and was 57.0, 61.8, 82.4 and 106.0 hours (P<0.001) for diets VH50 to VH10, respectively. With the exception of retention time which may be indicative of differences in digestive morphology, gross digestive function was similar in Matabele goats and Sabi sheep.