Department of Cattle Research, National Institute of Animal Sciences, Copenhagen, Denmark
*Present address : Division of Dairy Cattle Nutrition, National Dairy Research lnstitute. Karnal - 132 001, India
Online published on 5 January, 2012.
The studies were conducted on two non-lactating dairy cows fitted with a permanent rumen fistula and a re-enterant cannula in the duodenum, about 50 cm behind the pylorus. In a switch over design animals were fed on five isocaloric rations i.e. ammonia treated barley straw without urea (ration 1), and rations 2 to 5 contained 1.5% urea, 3 % urea, 9.4 % soybean meal (SBM) & 19.0% SBM respectively alongwith 5% molasses and 4% ammonia treated barley straw which were common to all treatments. The CP % in the rations 1 to 5 were 9.56,14.0, 17.94,13.63 and 16.25, respectively, thereby making ration 2 iso-nitrogenous with 4 and 3 with ration 5. After a preliminary feeding of 21 d on a particular ration, samples of feeds and duodenal contents (collected for 3 d) were analyzed for essential amino acids to find out the synthesis in the forestomachs. Ruminal OM digestions besides DM! were similiar on 5 test ratioas. (>n rations 1 -3 the essential amino acids supply to duodenum was 1.97 to 4.37 times higher than present in feed. This was 0.98 to 1.58 on ration 4 and 0.68 to 1.05 times on ration 5. There was a net increase of all essential amino acids (g/kg OM digested in the rumen and g/kg DMI) the increase being higher for ration 4 than ration 5. The differences of net amino acid synthesis between ration 1 and ration 4 varied from 1.34 to 4.92 g/kg OM digested in the rumen The greatest difference being for leucine which was followed bv Ivsine valine iso-leucine phenylalanine histidine threonine and methionine The study revealed that in the forestomachs of dairy cattle there was enhanced net svnthesis of amino acids in ammonia treated barley straw with or without urea supplementation and only marginal synthesis of amino acids on low level of SBM There was virtually no net synthesis with high level f SBM rather net loss of some essential mino acids occured The addition of supplemented urea to ammonia treated barley straw had no advantage with regards to amino acid synthesis in the forestomachs.
