Chemical composition and <i>in vitro</i> gas production of vetch (<i>Vicia sativa</i>) and some browse and grass species in northern Ethiopia

Abstract

Chemical composition and in vitro gas production of vetch (Vicia sativa) and some browse and grass species from northern Ethiopia were investigated. Vetch (fresh cut) was sampled in September and vetch hay samples were taken in October both during the early dry period. Samples of the browse and grass species were taken once per month during the rainy (June-August) and early dry (September-November) seasons in each year of the study period. Big variation was observed in the chemical composition of the browse and grass species. The browse species had relatively higher crude protein (CP) and acid detergent lignin (ADL) contents and lower neutral detergent fibre (NDF) contents than the grass species during both seasons. The highest CP content was observed in Albizia amara (24.7%) in the rainy season and in the fresh cut vetch (24.3%) in the dry season. Among the grass species, Digitaria abyssinica and Panicum miliaceum had relatively high CP contents during both the rainy and early dry seasons. Panicum coloratum had the highest NDF content in both seasons. The potential gas production was the highest (71.5 ml/0.2 g DM) in fresh cut vetch and the lowest (12.5 ml/0.2 g DM) in Ximenia american. The rate of gas production was the highest (0.081 ml h^–1) in Balanites aegyptica and the lowest (0.019 ml h^–1) in Combretum molle. Gas production was higher in fresh cut vetch than in the vetch hay, while the rate of gas production was higher in the hay than in the fresh cut vetch. In general, most of the browse species considered in this study had comparable CP and NDF contents to vetch and could be used as dry season supplementation for goats and other ruminants. However, further study is needed to understand the underlying causes of low gas production in some of the browse species and to evaluate animal response to supplementation of the promising browse species.

Keywords: chemical composition; in vitro gas production; vetch; browses; grasses

African Journal of Range & Forage Science 2006, 23(1): 69–75