Studies On Effectivity Of Rumen By-Pass Of N-Acetyl-DL-Methionine And Its Effects On Rumen Digestion And Metabolism In Sheep

Four experiments were conducted to study the apparent degradation of N-Acetyl-Methionine(NAM)under the condition of different pH value, in vitro simulating rumen fermentation system, and intraruminalinfusion, respectively, and to study the effects of different dosages of NAM on rumen digestion andmetabolism in sheep.Experiment1. NAM(0.75g/L)was solved in buffers of pH2.3 and pH6.5 and cultured at 39.5℃to studythe accumulative degradation of NAM at 0,1.5,3,6,9,12 hours after culturing, respectively. The resultsshowed that the accumulative degradation of NAM was 1.24% in buffers of pH2.3 and pH6.5 at 39.5℃.Experiment2. Different dosage of NAM(0,0.2g,0.4g,0.6g )was added into the mixure of artifical salivaand filtered rumen fluid(2︰1), respectively, and was fermented at 39.5℃to study the accumulativedegradation of NAM at 0,1.5,3,6,9,12 hours after fermentation, and to study the effects of differentdosage of NAM on in vitro rumen fermentation. The results showed the average degradation of NAM was3.98～4.34%, and the accumulative degradation of NAM was 6.61～7.51% at 12 hours after fermentation.There was no significant difference among groups(p>0.05). The dosage of NAM had little effects on pHvalue, the concentrations of ammonia nitrogen, acetic, propionic, butyric acid and microbial protein in thefermentation system, but there was tendency of decreasing pH value, increasing the concentrations ofammonia nitrogen, acetic, propionic, butyric acid with the dosage increase.Experiment 3. Four male Xinjiang Merino sheep, with 40 Kg of live body, fitted with permanent rumenfistula and T-type fistula at the proximal duodenum, were infused ruminally with graded levels of NAM(0,2, 3, 4 g.sheep-1.)respectively, twice a day gapping 12hours,in a 4×4 latin square design to study theapparent degradation of NAM in rumen at 0,1.5,3,6,9,12 after infusion, and the effects of the gradeddosage of NAM on rumen fluid dilution rate, disappearance rate of NAM and the outflow fromforestomach. The results showed that the average apparent degradation of NAM was 67.0%,72.7%,73.8%corresponding to 2, 3, 4 g.sheep-1. The degradation of 4 g.sheep-1 group was significantly higher than that of2g.sheep-1group (p﹤0.05). The rumen fliud dilution rate was decreased significantly 34.6%,47.9%( p<0.05) at the dosage of 6～8 g.sheep-1.d-1NAM. NAM reaching duodenum daily was 0.72, 0.94 and1.08 g,and disappearance rate of NAM from forestomach was 82.1%,84.3%,86.5%. The accumulative outflowfrom rumen 12 hours after infusion was 0.50, 0.59, 0.65g, respectively. Compared with 4 g.sheep-1.d-1group,NAM reaching duodenum daily and the outflow from rumen were significantly increased 50%, 30% by 8...