Effects of Non-Protein Nitrogen Sources on In Vitro Rumen Fermentation Characteristics and Microbial Diversity
Jinjia Zhu, Ao Ren, Jinzhen Jiao, Weijun Shen, Lingyuan Yang, Chuanshe Zhou, Zhiliang Tan
Abstract
Here, the effects of non-protein nitrogen sources on fermentation parameters and microbial diversity were explored using three fistula goats as rumen fluid donors. The experiments involved six fermenters in a replicated 3 × 3 Latin square design with three dietary non-protein sources [ammonium chloride (A), biuret (B), and glutamine (G)] as treatment factors. A dual-flow continuous culture fermentation system was used. Microbial protein content in group B was significantly lower than that in the other two groups ( P < 0.05). Ammonia nitrogen concentration significantly differed among the three groups ( P < 0.01), following the order of G > A > B group. The acetate-to-propionate ratio in group G was significantly lower than that in the other two groups ( P < 0.01). At the phylum level, the relative abundances of Cyanobacteria , Elusimicrobia , and Armatimonadetes were the highest in group G, being significantly higher than those in group B ( P < 0.05). At the genus level, the relative abundance of Ruminococcus_1 was significantly higher in group A than in group B ( P < 0.05). Overall, glutamine shifted the fermentation pathway from acetate to propionate, and the lower microbial crude protein content and relative abundances of the major fiber-degrading bacteria Ruminococcus_1 and protein-degrading bacteria Prevotellaceae_UCG-001 in group B indicate that biuret is not suitable as a dietary non-protein nitrogen source.