Seasonal dynamics on nutritive value, chemical estimates and in vitro dry matter degradability of some woody species found in rangelands of South Africa

Abstract

AbstractUnlocking browse species in semi-arid regions can be a key to improving the livestock productivity. The research was conducted to assess the browse species variation in chemical composition and in vitro dry matter degradability as influenced by seasonal (summer and winter) changes. Leaves from ten randomly selected browsable trees from sixteen species (Vachellia karroo, Senegalia nigrescens, Vachellia nilotica, Balanites maughamii, Berchemia discolor, Berchemia zeyheri, Bridelia mollis, Combretum collinum, Combretum imberbe, Dalbergia melanoxylon, Dichrostachys cinerea, Grewia monticola, Grewia occidentalis, Melia azedarach, Ormocarpum kirkii and Ziziphus mucronata) were harvested before defoliation from the site in two seasons (summer and winter) and dried at room temperature and then ground for analysis. Two-way analysis was used to analyse chemical composition and in vitro ruminal dry matter degradability. Melia azedarach (343.7 g/kg DM) had the highest (p < 0.0001) CP content in summer. In winter, B. maughamii (210.3 g/kg DM) had the highest (p < 0.05) crude protein content. Combretum collinum (2.90 Mcal/kg) had a highest (p < 0.0001) metabolizable energy value in summer. Bridelia mollis, B. maughamii, B. discolor, C. collinum, C. imberbe, O. kirkii, S. nigrescens, V. nilotica, G. occidentalis and B. zeyheri had the same (p > 0.0001) dry matter degradability (DMD) 48 values across two seasons. In both seasons, most of these browse species have the potential to supplement low quality natural grasses because they go beyond the minimum requirement of protein and have coherent amounts of fibre concentration. There is a need to assess the bioactive compounds found in these browse species for the amelioration and also to maximize browsing of these species.