Seasonal botanical and chemical composition of sheep and goat diets on a common range in eastern Africa

The botanical and chemical composition, intake and digestibility of local sheep (Ovis aries) and goat (Capra hirtus) diets were evaluated over the wet (growing) and dry (dormant) seasons. Diet botanical composition was related to the vegetation composition on the range. Commiphora riperia and Acacia tortilis were the most dominant tree species, while Duosperma kilimandscharicum and Premna hildebrandtii were the most dominant shrub species. Enteropogon macrostachyus, Cenchrus ciliaris and Chloris roxburghiana were the most abundant grass species, while Brepharis integriifolia, Commelina benghalensis and Macrotylomma axillare were the most dominant forb species. Grasses increased towards the end of the wet season and the beginning of the dry season, while the forbs decreased. Eragrostis caespitosa, Cenchrus ciliaris, Eragrostis superba, Enteropogon macrostachyus and Themeda triandra were the most dominant grass species in sheep diets during both seasons, accounting for over 82% of the diet. Acalypha fruticosa, Grewia similis and G. bicolor were the most important browse species in goat diets in both seasons, while Eragrostis caespitosa and E. superba were the most common grass species during both seasons. Overall, goat diets comprised 81% browse, 17% grass and 2% forbs during the wet season; and 82% browse, 15% grass and 3% forbs during the dry season. Whilst the goat diets had higher (P < 0.05) crude protein (CP) content than sheep diets during both seasons, the sheep diets were lower in lignin content than goat diets during the wet season. Overall, the goat diets were lower in neutral detergent fibre (NDF) and acid detergent fibre (ADF) than sheep diets during both seasons. There was no difference (P < 0.05) in digestibility between the two animal species. However, it was higher (P < 0.05) during the dry than the wet season. Although sheep and goats are commonly herded together in east African rangelands, they have differing abilities to utilise forages. These differences must be taken into consideration in grazing management decisions, and selected grazing areas should be able to cater for the forage requirements of both species. Keywords: diet selection, forage, free-grazing, Kenya, range herbivores,, rangeland, seasonal variation African Journal of Range & Forage Science 2004, 21(1): 11–1

Effect of Acacia tortilis pods on intake, digestibility and nutritive quality of goat diets in southwestern Eritrea

Fresh Acacia tortilis pods were mixed with low quality native grass hay to form the following five rations: 100% hay (T1), 25% pods and 75% hay (T2), 50% pods and 50% hay (T3), 75% pods and 25% hay (T4) and 100% pods (T5) on ‘as fed' weight basis. Fifteen male Barka goats, approximately one year old and 10–15kg body weight, were randomly assigned to the five rations and fed in individual pens. Chemical composition, dry matter intake (DMI), in vitro dry and organic matter digestibility and body weight changes of the animals were evaluated. The average crude protein content of the pods was about 47% higher than the 7% minimum required for normal rumen function, while that of the hay was about 13% below. Percent ash, neutral detergent fibre (NDF), acid detergent fibre (ADF), hemi-cellulose (HC), cellulose (CL) and acid detergent lignin (ADL) contents were higher in the hay than in the pods. The pods were, however, generally higher in Ca, P, Mg and Na than the hay. Average DMI (g d-1 and g kg-1 LBW), percent in vitro dry and organic matter digestibility and body weight gains (total kg and gd-1) increased with an increase in A. tortilis pods, up to 75% level and then begun to decline. However, despite the decrease, T5 still had significantly (P < 0.05) higher feed digestibility and body weight gains than T2 and T3. Thus, supplementing low quality range herbage with Acacia pods can considerably improve the nutritive value of range livestock diets, particularly during the dry season when other types of fodder are of extremely low quality. Keywords: Acacia pods, Barka goat diet, range forage, pastoralists, semi-arid EritreaAfrican Journal of Range & Forage Science 2003, 20(1): 59–6