Seasonal variations in grazing behaviour and forage nutrient utilization by goats on a semi-arid reconstituted silvipasture

摘要

Seasonal variation in the feeding behaviour of Jamunapari and Barbari goat breeds and their utilization of browse and grass nutrients was evaluated in a promising three-tier (Acacia nilotica-Leucaena leucocephala-Cenchrus ciliaris) reconstituted pasture during the winter, summer and rainy season of the years 1987, 1988 and 1990. A distinct diurnal pattern of feeding was observed with both breeds, and they spent more time foraging (P < 0.05) during the rainy season (504.9 min) than in the winter (376.5 min) or summer (266.9 min). Preference of grazing goats for certain plant species in relation to others was evident, with distinct seasonal variations. Goats spent more time (52.9-62.0%) on browse during summer and the rainy season, while in winter they spent more of their foraging time on grasses (52.0-61.9%). Among the browse species, A. nilotica was preferred over L. leucocephala in all seasons irrespective of breed. DM intake (g per kg BW~(0.75)) varied widely (P < 0.05) from season to season, with minimal values in summer (49.2-52.8) that increased to 68.5-69.7 in winter and 84.3 in the rainy season. There was no breed difference in DM intake or proximate composition and nutrient digestibility of ingested herbage. Available nutrient content of ingested forage was found to be sufficient to meet nutrient requirements of adult goats for maintenance (NRC, 1981). Reconstituted three-tier pasture dominated by native plant species such as A. nilotica and Cenchrus species appears to have the potential to sustain the nutrient requirements of goats without adverse seasonal fluctuations in pasture quality.