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Seasonal botanical and chemical composition of sheep and goat diets on a common range in eastern Africa
Abstract
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):
11–19
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):
11–19
