Silage quality, dry matter intake and digestibility by West African dwarf sheep of Guinea grass (Panicum maximum cv Ntchisi) harvested at 4 and 12 week regrowths

Abstract

An all year round pasture is not always guaranteed in the tropics especially in Nigeria as half of the period is a dry season. In order to circumvent the pasture scarcity during drought, silage making is paramount. In this vein, nutritive value of silage made from Guinea grass (GG) frequently harvested at 4 and 12 week regrowth was assessed by West African dwarf (WAD) sheep. Four weeks GG (4WGG) and 12 weeks GG (12WGG) were mixed to make treatments: 12 week GG (12WGG), 4 week GG (4WGG), 25% 4WGG + 75% 12WGG, 50% 4WGG + 50% 12WGG and 75% 4WGG + 25% 12WGG. Grass mixtures were subjected to silage for 42 days. Quality and chemical composition of the silage was assessed. Silage was also fed to WAD sheep to determine the dry matter intake (DMI) and dry matter digestibility (DMD). Crude protein for 4WGG was 17.5% higher than that of 12WGG. Silage colour was normal except for 12WGG that showed light yellow. The pH value and temperature ranged from 4.2 - 5 and 25 - 27.5oC, respectively. Pleasant and firm textures of the silages were observed irrespective of the age of the grass and the ratio of mixtures. The DMI significantly ranged from 617.2 g in 4WGG to 759.1 g in 50% 4WGG + 50% 12WGG. Variation occurred in DMD among the sheep ranged from 61.8 in 12WGG to 73.5 in 75% 4WGG + 25% 12WGG. Results showed that silage quality was better and that dry matter intake and digestibility were low by the sheep fed 4 or 12 week grass regrowth but the animals performed well at different combinations of grasses, suggesting an effective utilization of both young and fibrous grasses.