In-Situ Digestibility of Selected Fibrous Feedstuffs at Varying Levels of Concentrate Supplementation in Rumen-fistulated Brahman Bull

Abstract

A series of experiments were done to determine the effects of 20% and 40% levels of concentrate supplementation on the in-situ degradability of dry matter (DMD), organic matter (OMD), and neutral detergent fibre (NDFD) in a rumen-fistulated Brahman bull. Treatment diets included: T1—untreated rice straw, T2 – urea-treated rice straw, T3 – Napier soilage, T4 – Napier silage, T5 – sugarcane tops, and T6 – dried cogon grass. The nylon bags containing the treatment diets were incubated in the rumen at two periods: first at a 20% concentrate (20% of total diet D.M.) level, and second at a 40% concentrate (40% of total diet D.M.) level in a bull-fed Napier grass as basal diet. There were significant differencesin DMD and OMD among feedstuffs tested at a 20% level of concentrate supplementation; the highest was with Napier silage. Neutral detergent fibre (NDF) digestibility was highest with urea-treated rice straw (UTRS) and lowest in Napier silage and sugarcane tops. At a 40% level, in situ DMD, OMD, and NDFD decreased significantly with Napier silage, UTRS, and Cogon, respectively, which were associated with a drop in rumen pH. Most significant drop in NDF digestibility was with rice straw, Napier soilage, and Cogon. Hence, further study is recommended on evaluating fibre degradability and incubation.