Seasonal variation in time spent foraging by indigenous goat genotypes in a semi-arid rangeland in South Africa

摘要

The feeding behaviour of Xhosa lop-eared (XLE), Nguni (NGN) and Nguni x Boer crossbred (NBC) goat genotypes was compared in a False Thornveld rangeland by recording time spent on browsing, grazing and other non-foraging activities in four seasons; cool-dry (June to August); hot-dry (September to October), hot-wet (November to February) and post-rainy (March to May). The False Thornveld rangeland consists of diverse plant species dominated by Acacia karma, Grewia occidentalis, Scurtia myrtina Themeda triandra, Panicum maximum, Digitaria eriantha, Eragrostis spp., Cynodon dactylon and Pennisetum clandestinum, and receives an annual rainfall of not more than 490 mm. Four observers monitored 8 goats per genotype at 15-minute intervals for 4 h (0800-1200 h) in the morning and 4 h (1200-1600 h) in the afternoon. Genotype, season and time of day had an effect on the feeding behaviour of goats on the rangeland (P < 0.05). Xhosa lop-eared goats spent more time browsing (P < 0.05) in the cool-dry and hot-wet seasons compared to NGN and NBC goats. Nguni goats spent more time browsing (P < 0.05) in the hot-dry season. Time spent grazing varied among the goat genotypes with the NBC cross spending more time grazing (P < 0.05) in hot-dry, cool-dry and post-rainy seasons. Generally, season and time of day had no effect on time spent on non-foraging activities for the three goat genotypes. It was concluded that NBC goats spent more time grazing compared to other genotypes across all seasons. Conversely, XLE and NGN goat genotypes spent more time feeding on browse species across seasons. Xhosa lop-eared and NGN goat genotypes are thus adapted to the surrounding environment for they may utilise resources more efficiently. (c) 2010 Elsevier B.V. All rights reserved.