Effects of Increasing Level of Dietary Rice Straw on Chewing Activity, Ruminal Fermentation and Fibrolytic Enzyme Activity in Growing Goats

Abstract

Effects of increasing dietary rice straw on chewing activity, ruminal fermentation, and fibrolytic enzyme activity in growing goats were investigated in a 4×4 Latin Square experiment. The goats were offered four diets with an increasing proportion of rice straw (i.e. 0.05, 0.10, 0.15 and 0.20, respectively, on dry matter basis). Increasing level of rice straw increased (P linear effect <0.05) the time spent on eating, ruminating, and chewing. The ruminal pH and acetate: propionate ratio were increased (P linear effect <0.05), while the NH 3 -N concentration was decreased (P linear effect <0.01). Increasing level of rice straw in the diet increased (P linear effect ≤0.01) molar proportion of acetate and isovalerate, and decreased (P linear effect <0.01) molar proportion of propionate. The CMCase, xylanase and cellobiase activities in the rumen were decreased (P linear effect <0.05) with increasing level of dietary rice straw, whereas the avicelase activity was increased (P linear effect <0.01). In summary, increased level of rice straw elevated the dietary neutral detergent fibre (NDF) content in the diet and had a great impact on chewing activity and ruminal fermentation.

Supplementation of rice straw (Oryza sativa) with exogenous fibrolyticenzymes improves in vitro rumen fermentation characteristics

“…Rice is the most extensively grown cereal crop, the staple food in Sri Lanka, and an important traditional feed source for ruminants, providing a potential solution for dry season feed stress in the livestock industry (1). In Sri Lanka a large proportion of the harvested rice straw is used in the paper industry, and a small quantity of straw is used for the feeding and bedding of cattle and buffaloes; most of the straw is either ploughed in or burned directly on the field, which causes environmental pollution (2).…”