Nutrient intake, digestibility and rumen fermentation characteristics of sheep fed on selected forage sweet potato cultivars

Abstract

ABSTRACT Selected forage sweet potato cultivars (Ipomoea batatas Lam) have superior forage characteristics, have high rates of regeneration after harvest, are able to smother weeds and can tolerate diseases and moisture stress. However, little information is documented on their feeding value. The study objective was to determine nutrient intake, digestibility and rumen fermentation characteristics of sheep fed on four selected forage sweet potato cultivars (K158, Marooko, Mugande and Wagabolige). Cultivars did not influence intake of dry matter (DM) (93.8–98.1), organic matter (OM) (82.0–85.6), neutral detergent fibre (NDF) (37.6–38.8 g/kg W0.75) and metabolizable energy (0.94–0.99 MJ/kg W0.75); digestibility of DM (740.3–744.1) and OM (747.0–751.7 g/kg DM) and intake of digestible DM (69.8–72.6) and OM (61.3–64.4 g per kg W0.75); rumen pH (6.80–6.86), molar percentages of acetate (68.34–69.59), propionate (21.35–22.58), butyrate (7.43–7.57) and acetate to propionate ratio (3.03–3.20). Cultivars influenced intake of crude protein (CP) (10.7–16.9) and acid detergent fibre (ADF) (25.9–28.5 g/kg W0.75). Digestibility of CP (655.7–821.1), NDF (594.1–712.8) and ADF (477.0–483.7 g/kg DM); intake of digestible CP (7.0–13.9) and NDF (22.4–27.7 g per kg W0.75) were also influenced by cultivar. CP and NDF digestibility differed among all four cultivars with Morooko and K158 having the highest CP and NDF digestibility, respectively. Sheep fed on K158 and Wagabolige ingested similar quantities of digestible CP (11.6–11.8 g per kg W0.75), which was lower than in Marooko (13.9 g per kg W0.75). The four cultivars provided superior feeds to sheep which classify them as high quality forages. Hence they have the potential to improve livestock production in Kenya.