Study On Stability Of Different Met Products And Their Effects On Protein Metabolism And Performance Of Steers

Five experiments were conducted in the present studies to investigate the stability and metabolism of DL-Met, MHA,adsorptive-MHA(A-MHA),grease-embedded-Met (G-Met) and fatty-acid-embedded-Met(FA-Met) in the gastrointestinal tract and their effects on protein metabolism and performance of steers combined with nitrogen balance experiment and blood indexes.Five tests were in vitro experiment,/n situ experiment,duodenal DL-Met infusion experiment,Met medicate in the rumen experiment and feeding experiment.The energy requirement of test diet was 1.1 multiplication of maintenance requirement.The crude feed was wheat bran and concentrate feed was made primary of corn and soybean meal.DL-Methionine was Zhuyou brand(^99%). The PRMet were made by grease or fatty acid embedded DL-Met.MHA was supplied by USA Nuoweisi international limited company.The A-MHA was mixed by MHA and stone meal.In experiment 1, the stability of these products in artificial saliva , artificial really gastric juice, rumenal fluid and duodenal fluid were investigate in a in vitro experiment.The results showed that MHA had certain by-pass rumen character.and the by-pass rumen character of A-MHA was better than that of fluid MHA.The by-pass rumen character of G-Met and FA-Met was better than that of MHA or A-MHA,and the G-Met was better than FA-Met.In experiment 2, 4 steers fitted with fistula in the rumen, the proximal duodenum and dismal ileum were used to study the disappearance rate in rumen,postrumen,small56intestine.large intestine, whole gastrointestinal tract and utilization rate in the gastrointestinal tract of DL-Met, A-MHA,G-Met and FA-Met. The results indicated that DL-Met disappeared completely after 4h Incubation in the rumen.The stability of FA-Met was better than that of DL-Met. A-MHA and G-Met were better than FA-Met.The disappearance rate in rumen,postrumen,small intestine.large intestine, whole gastrointestinal tract of G-Met was the highest of these products, and so was the utilization rate in the gastrointestinal tract of G-Met.In experiment 3,DL-Met was infused into the duodenum in a gradient manner to quantify the optimal amount of DL-Met in basal diet by observing the difference of average daily gain(ADG), nitrogen balance, plasma amino acid(PAA) and digestive rate of amino acid in the small intestine among treatments in a 4x4 Ladin square experimentThe treatments were basal diet plus 0( I ),9( II), 13(111) and 17(IV)g/d DL-Met.The first 12d of each test period was an adjustment period and the following 7d was for sample collection.The determination of digesta flows were conducted by Cr2O3 marking method. The results showed that the ADG of group HI were highest,and was 15.27% higher than the control(P<0.05).RN of group II and group HI was significantly higher than group I (P<0.05). RN of group in was higher than that of group II .RN/DN of group II and group HI were significantly higher than that of group I (P<0.05),and RN/DN of group III was higher than that of group II .Urine urea nitrogen of group III was significantly lower than that of I group(P<0.05).Digestive rate of N of group HI were highest, and was 5.72%higher than that of group ffl.Plasma NH3-N content of group HI were significantly higher than that of group I (P<0.05),and there was no significant defference in Plasma urea nitrogen content amoung all groups(PX).05). The content of plasma Cys and Met of group IV were significantly higher than that of the rest(P<0.05),but Ser and He was the vice versa Plasma Leu content of group I and II were higher than that of group HI and IV (P<0.05).Plasma Lys content of group HI was significantly lower than that of the rest(P<0.05).Plasma BACC content of group I and II was higher than that of group HI and rV(P<0.05).Plasma EAA content of group III was significantly lower than that of the rest(P<0.05). Plasma NEAA content of group I was significantly higher than that of the rest(P<0.05).PIasma TAA content was reduced with the increase of duodenal DL-Met infusion quantity.The apparent digestive rate of Asp,Thr,Ser,...