Digestion and Duodenal Flow of Ammonia-Treated Straw, and Sodium Hydroxide-Treated Straw Supplemented with Urea, Soybean Meal or Fish Viscera Silage

Abstract

To compare the value of N in ammonia-treated straw with other N sources, 4 iso-nitrogenous and iso-energetic diets were compared at maintenance level to sheep. The diets consisted of the following: ammonia-treated straw + barley; sodium hydroxide-treated straw + barley + urea; sodium hydroxide-treated straw + barley + extracted soybean meal; and sodium hydroxide-treated straw + barley + fish viscera silage. The digestibility of N was low when the ammonia-treated straw diet was fed. For this diet the amount of N digested in the rumen also was lower compared with the other diets. Duodenal flow of N and the amount of N excreted in the feces was higher. A portion of the ammonia was tightly bound to the straw and was not released, during the passage through the alimentary tract. No difference could be demonstrated between the urea, extracted soybean meal or fish viscera silage diets in the amount of nonammonia N flowing to the duodenum. The lack of difference was explained by the maintenance level of feeding and the high proportion of barley in the ration, supplying soluble energy for synthesis of microbial protein in the rumen.