Effects of Different Levels of Concentrate in Complete Rations on Nutrient Digestibilities and Ruminal Metabolites in Sheep and Growth Performance in Korean Native Bulls

Abstract

Objectives of the present study were to investigate effects of different levels of concentrate in complete rations on nutrient digestibilities and ruminal fermentation in sheep and growth performance in Korean native bulls. Increasing levels of concentrate (35, 50, 65, and 80% of complete rations) improved digestibilities of dry matter (DM), crude protein (CP) and ether extract (EE) without affecting digestibility of neutral detergent (NDF) and acid detergent fiber (ADF). Increasing levels of concentrate decreased ruminal fluid pH but increased concentrations of NH3-N, propionic acid, and total volatile fatty acids (VFA). Both the disappearance rates of DM and nitrogen (N) in an in sacco study were linearly increased as the levels of concentrate in complete rations increased. Meanwhile, increasing levels of concentrate in complete rations improved growth rate and feed conversion ratio in Korean native bulls. In conclusion, the complete rations containing 80% concentrate showed better digestibility and energy supply than those of the lower levels (35, 50 and 65%) of concentrate of the rations, resulting in improved growth performance of Korean native bulls.