Vázquez-Añón M, Cassidy T, McCullough P, Varga G A
Novus International, Inc., St. Charles, MO 63304, USA.
J Dairy Sci. 2001 Jan;84(1):159-66. doi: 10.3168/jds.S0022-0302(01)74465-7.
A dual effluent continuous culture system was used to investigate the effects of inclusion of Alimet (Novus International, Inc., St. Louis, MO) feed supplement [an 88% aqueous solution of dl, 2-hydroxy-4-(methylthio) butanoic acid (HMB)] in the diet on nutrient digestibility, bacterial protein synthesis and ruminal disappearance of HMB. Four fermenters were fed three times daily a basal diet that consisted of 50% grain mixture and 50% forage for 9 d. In experiment 1, four concentrations of HMB (0, 0.20, 0.77, and 1.43% DM basis) were added to the diet and fed to the fermenters twice daily. In experiment 2, two concentrations of dietary HMB (0 and 0.88% DM basis) were fed twice daily and evaluated with two solids retention times (16.7 vs. 25.0 h) and two liquid dilution rates (0.15 vs. 0.125 h(-1)). Increasing the amount of HMB in the diet did not affect nutrient digestibility, volatile fatty acid concentrations, or ruminal escape of HMB. Bacterial protein synthesis was improved with the addition of HMB during high and low retention times. The extent of HMB escaping ruminal degradation ranged from 21.6 to 43.2% and was highest at the lower retention time. It can be concluded that a fraction of HMB survives rumen microbial degradation and, therefore, provides a rumen-protected form of methionine at the same time that it improves bacterial protein synthesis.
采用双流出物连续培养系统，研究日粮中添加Alimet（诺伟司国际公司，密苏里州圣路易斯）饲料添加剂[dl，2-羟基-4-（甲硫基）丁酸（HMB）的88%水溶液]对养分消化率、细菌蛋白质合成和HMB瘤胃消失率的影响。四个发酵罐每天分三次投喂基础日粮，基础日粮由50%谷物混合物和50%草料组成，持续9天。在实验1中，向日粮中添加四种浓度的HMB（以干物质计分别为0、0.20、0.77和1.43%），并每天分两次投喂给发酵罐。在实验2中，每天分两次投喂两种浓度的日粮HMB（以干物质计分别为0和0.88%），并在两种固体保留时间（16.7小时对25.0小时）和两种液体稀释率（0.15小时-1对0.125小时-1）下进行评估。日粮中增加HMB的量对养分消化率、挥发性脂肪酸浓度或HMB的瘤胃逃逸没有影响。在高和低保留时间添加HMB均可改善细菌蛋白质合成。HMB瘤胃降解逃逸程度在21.6%至43.2%之间，在较低保留时间时最高。可以得出结论，一部分HMB在瘤胃微生物降解中存活下来，因此，在提高细菌蛋白质合成的同时，提供了一种瘤胃保护形式的蛋氨酸。
