Ruminal Degradation Characteristics and Small Intestinal Digestibility of Rumen Undegraded Protein of Six Kinds of Commonly Used Roughages for Steers

This experiment was conducted to determine the ruminal degradation characteristics and small intestinal digestibility of rumen undegraded protein( RUP) of 6 kinds of commonly used roughages: ryegrass,hemarthria compressa,sweet potato stem,corn stover silage,corn stover and rice straw. Three Xuanhan steers fitted with permanent ruminal cannulas were used. Nylon-bag technique was used to evaluate the ruminal degradability and effective digestibility of dry matter( DM),crude protein( CP),neutral detergent fiber( NDF) and acid detergent fibre( ADF). Modified three-step in vitro method was used to evaluate small intestinal digestibility of RUP of the roughages. The results showed as follows: 1) the DM effective degradability of ryegrass and sweet potato stem was significantly higher than that of hemarthria compressa,corn stover silage,corn stover and rice straw( P0.05),which were decreased in the above order. CP effective degradability and ADF effective degradability of ryegrass were significantly higher than those of sweet potato stem,hemarthria compressa,corn stover silage,corn stover and rice straw( P0.05),which were decreased in the above order. NDF effective degradability showed ryegrass sweet potato stem corn strawsilage hemarthria compressa corn stover rice straw,and the differences among roughages were significant( P0.05). 2) The small intestinal digestibility of RUP of hemarthria compressa,corn stover and rice strawwas not significantly different( P 0.05),and was significantly higher than that of corn stover silage,ryegrass and sweet potato stem( P0.05),which was decreased in the above order. Intestinal digestible CP content of showed ryegrass sweet potato stem hemarthria compressa corn stover silage corn stover rice straw,and the differences among roughages were significant( P0.05). In conclusion,ruminal degradation characteristics of roughages are dissimilar,and the potential that can provide digestible crude protein for small intestine is different. The effective degradability of DM,CP,NDF and ADF of ryegrass is the highest,small intestinal digestibility of RUP of hemarthria compressa,corn stover and rice strawis higher,and ryegrass and sweet potato stem have higher intestinal digestible crude protein content.