本试验旨在研究N-乙酰-DL-蛋氨酸（NAM）对绵羊瘤胃环境参数的影响及其在前胃的表观消失率。选取4只体重约35 kg安装有永久性瘤胃瘘管和十二指肠瘘管的波尔山羊羯羊，采用4×4拉丁方设计，经瘤胃瘘管分别投注0、4、6、8 g/d NAM；共进行4期试验，每期试验16 d，其中预试期10 d，正试期6 d。正试期前3天采瘤胃液，后3天采十二指肠食糜，用于测定瘤胃液后送率、pH、渗透压以及NAM在前胃的表观消失率。结果表明：1）投注6和8 g/d NAM显著降低了瘤胃液后送率和pH（P<0.05），并且显著提高瘤胃液渗透压（P<0.05）。2）投注后1.5~12.0 h各组NAM在前胃的表观消失率平均值在68.0%~74.9%，投注后12.0 h时，各组NAM表观消失率在79.8%~86.9%。总之，NAM对瘤胃消化环境有不良影响，能够降低瘤胃液的后送率、pH，提高瘤胃液渗透压，并且在前胃有较高的表观消失率（12.0 h时约80%）。在本试验条件下，经瘤胃投注4.0和8.0 g/d NAM对绵羊以上负面影响较大。

This study was conducted to study the effects of N-acetyl-DL-methionine (NAM) on environmental parameters in rumen and the apparent disappearance rate in forestomach of sheep. Four 35 kg Boer goat wethers fitted with ruminal and duodenal cannulas were used in a 4×4 Latin square design, and were ruminally administered with graded levels of NAM (0, 4, 6 and 8 g/d, respectively); the experiment consisted of 4 periods with 16 days per period (10-day pre-experiment and 6-day experiment). The samples of rumen fluid and duodenal chymus were collected in the first 3 days and the last 3 days of experimental period, respectively, to determine evacuation rate, pH and osmotic pressure of rumen fluid, and the apparent disappearance rate of NAM. The results showed as follows: 1) the evacuation rate and pH of rumen fluid of sheep administered with 6 and 8 g/d NAM were significantly decreased (P<0.05), however, the osmotic pressure of rumen fluid was significantly increased (P<0.05). 2) The mean of apparent disappearance rate of NAM in forestomach after administered for 1.5 to 12.0 hours was 68.0% to 74.9%, and the disappearance rate of NAM in rumen after administered for 12.0 hours was 79.8% to 86.9%. In conclusion, NAM is not beneficial for ruminal digestion environment, it can decrease evacuation rate and pH, but increase osmotic pressure of rumen fluid, meanwhile, it has high apparent disappearance rate in forestomach (about 80% after 12 hours). Under condition in the present study, the ruminal administration of 6 and 8 g/d NAM has greater adverse impacts on sheep.