Effects of mixing red clover with alfalfa at different ratios on dynamics of proteolysis and protease activities during ensiling

作者：Xujiao Li, Jipeng Tian, Qing Zhang, Yun Jiang, Zhe Wu, Zhu Yu · 发表于：Journal of Dairy Science · 年份：2018 · DOI：10.3168/jds.2018-14763 · 被引用次数：99 · 研究领域：Ruminant Nutrition and Digestive Physiology、Phytase and its Applications、Phytoestrogen effects and research

This study was conducted to study the effects of ensiled alfalfa ( Medicago sativa ) and red clover ( Trifolium pratense ) at different ratios on dynamics of fermentation parameters, N distribution, protein fractions, and protease activities during ensiling. Alfalfa and red clover were harvested and wilted to 35 and 25% dry matter, respectively, chopped to 1 cm, mixed, weighed into 1.0-L buckets at a density of 700 g/L, and ensiled for 1, 3, 7, 15, and 30 d at 30°C. The treatments were mixing ratio of alfalfa to red clover at 100:0, 70:30, 50:50, 30:70, and 0:100 (R0, R30, R50, R70, and R100, respectively; fresh weight). For each ensiling duration, 3 replicates of each treatment were prepared. With increasing proportion of red clover in silage, total N content and proportions of nonprotein N, peptide N, free amino acid N, and NH 3 -N decreased linearly, and PC (indigestible true protein, acid detergent insoluble N) proportion increased linearly after ensiling. Moreover, the final pH was lower in R50 and R100 than R0 (4.29, 4.20 vs. 4.48, respectively) on d 30. Also, lactic acid concentration on d 30 was higher in R50, R70, and R100 silage compared with R0 (7.77, 7.66, and 8.76 vs. 6.34, % of dry matter, respectively). The proportion of NH 3 -N in R50 was lower than in R0 but closer to R100 after ensiling. During ensiling, proteases including carboxypeptidase, aminopeptidase, and acid proteinase activities decreased as red clover proportion increased. However, no differences w...