Nutritional studies on East African herbivores

Abstract

1. A series of digestibility trials was done using four animals of each of the following species: Friesian cattle (Bos taurus), Boran zebu cattle (Bos indicus), Corriedale sheep, fattailed sheep, eland (Taurotragus oryx Pallas), Coke's hartebeest (Alcelaphus buselaphus cokei Günther), Thomson's gazelle (Gazella thomsonii Günther) and bush duiker (Sylvicapra grimmia L.)2. Two batches of pelleted food were prepared from ground maize cobs, cassava, wheat bran, maize bran and decorticated cottonseed cake. For each batch, five diets (A–E) were prepared containing 65 (A)–135 (E) g crude protein (nitrogen × 6·25)/kg dry matter. The crude-fibre contents of all the diets were similar (120–138 g/kg dry matter)3. The animals were given the high-protein diet (E), then given diets with decreasing protein contents finishing with the low-protein diet (A). The antelope and half the sheep were given diets from the first batch of pelleted food, the other four sheep and all the cattle were given diets from the second batch of food4. In sheep, there were significant differences in digestibility between the two batches of food5. There were no significant differences in the over-all mean digestibilities of all diets when given to cattle (both species) and sheep. However, with diet E, dry-matter digestibility was higher in sheep than in cattle (P < 0·05): the reverse was true with diet A (P < 0·001). Crude-fibre and crude-protein digestibilities followed a similar pattern. The differences between Corriedale and fat-tailed sheep were not significant. The only significant difference between the two species of cattle was the higher digestibility of crude protein in Borans given diet E (P < 0·05)6. The over-all mean digestibility of the dry matter was higher (P < 0·001) in hartebeest and duiker than in sheep; in Thomson's gazelle (P < 0·01) and eland (P < 0·001) it was lower than in sheep. The values for crude-fibre digestibilities varied in a similar way7. The mean apparent digestibility of crude protein was higher (P < 0·001) in eland, hartebeest and duiker than in sheep and gazelle8. The results are discussed in relation to the feeding habits and digestive physiology of the various species.