Effects Of Coated Methionine And Lysine On Nitrogen Metabolism And Performance In Lambs

Four trials were conducted to determine the effects of supplemental coated methionine (RPmet) and lysine (RPlys) on the nitrogen balance and physiological criteria of plasma and performance in lambs. The research comprised two parts, one were the tests of properties of the RPAA products and the other part consisted of three animal experiments in which 27 newly weaned three-month old cross-breed lambs were assigned according to 3x3 factorial design with RPmet and RPlys as the two factors. The results showed that: (1) The disappearance rates of RPmet and RPlys coated by pH sensitive polymer were 29.1% and 55.2% respectively following 12 hours of incubation in rumen, and the release rates of RPmet and RPlys exceeded 90% following 3 hours incubation in artificial abomasum juice and small intestine juice respectively. The above dates demonstrated that this coated RPAA products had good rumen by-pass and abomasum soluble properties. (2) The nitrogen retention in lambs and the apparent digestibility of nitrogen in diets were improved with dietary RPmet and RPlys levels. (3) The concentrations of the plasma urea, plasma total free amino acids and plasma free essential amino acids tended to decrease with dietary RPmet and RPlys levels. (4) The average daily gain increased significantly and the percent of feed to gain decreased significantly with dietary RPmet and RPlys levels and the dietary RPmet and the dietary RPlys had significantly interaction over the average daily gain and feed conversation rate. (5) Based on the diets with 11.3% crude protein which were consisted of concentration of com and soybean meal and forage of corn silage and hay, the recommendation supplemental levels of RPmet and RPlys were 3-6 and 5-10 g/d respectively.