Guo Wenliang, Na Meila, Liu Shuwei, Li Kenan, Du Haidong, Zhang Jing, Na Renhua
College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China.
Grassland Research Institute of Chinese Academy of Agricultural Sciences, Hohhot 010010, China.
Animals (Basel). 2024 Dec 26;15(1):34. doi: 10.3390/ani15010034.
Alfalfa silage due to its high protein can lead to easier feeding management, but its high proportion of rumen-degradable protein can reduce rumen nitrogen utilization. Nevertheless, increasing dietary energy can enhance ruminal microbial protein synthesis. Thirty-two Suffolk female sheep were used in this study, with a 2 × 2 factorial arrangement of treatment. The four treatments were a combination of two forage types (alfalfa hay; AH vs. alfalfa silage; AS) and two rumen-degradable starch levels (low RDS; LR vs. high RDS; HR) with a 15 d adaptation and 60 d experimental period. The rumen content and rumen epithelium samples were collected after slaughter. Feeding AS increased the rumen isobutyrate, valerate, ammonia-N (NH-N) concentration, urase activity, and papillae height ( < 0.05) and reduced the feed to gain (F:G), rumen bacterial protein (BCP), rumen lactic acid concentration, and papillae width ( < 0.05) of sheep. Increased RDS in the diet improved the daily matter intake, average daily gain, and rumen weight, reduced the F:G, and enhanced the rumen nitrogen capture rate by decreasing total amino acids and the NH-N concentration to increase BCP, aquaporins 3 gene, and protein expression. The rumen microbiota also changed as the HR diet reduced the Chao index ( < 0.05). The metabolomics analysis showed that feeding AS upregulated the rumen tryptophan metabolism and steroid hormone biosynthesis, while the purine metabolism, linoleic acid metabolism, and amino acid biosynthesis were downregulated. Furthermore, increased RDS in the diet upregulated rumen lysine degradation and sphingolipid metabolism, while aromatic amino acid biosynthesis was downregulated. Additionally, the correlation analysis results showed that ADG was positively correlated with 5-aminopentanoic acid, and three microorganisms (unclassified_f__Selenomonadaceae, Quinella, Christensenellaceae_R-7_group) were positively correlated with the rumen isobutyrate, valerate, NH-N concentration, urase activity, tryptophan metabolism, and steroid hormone biosynthesis and negatively correlated with linoleic acid metabolism and amino acid biosynthesis in sheep. In summary, increased RDS in the diet improved the growth performance and rumen N utilization and reduced bacterial diversity in sheep. The alfalfa silage diet only increased feed efficiency; it did not affect growth performance. Additionally, it decreased rumen nitrogen utilization, linoleic acid, and amino acid biosynthesis. Nevertheless, there were limited interactions between forage and RDS; increased RDS in the AS diet enhanced the nitrogen capture rate of rumen microorganisms for alfalfa silage, with only slight improvements in the purine metabolism, linoleic acid, and amino acid synthesis.
苜蓿青贮饲料因其蛋白质含量高，可使饲养管理更轻松，但其瘤胃可降解蛋白比例高会降低瘤胃氮利用率。然而，增加日粮能量可提高瘤胃微生物蛋白合成。本研究选用32只萨福克母羊，采用2×2析因设计处理。四种处理为两种饲草类型（苜蓿干草；AH与苜蓿青贮饲料；AS）和两种瘤胃可降解淀粉水平（低瘤胃可降解淀粉；LR与高瘤胃可降解淀粉；HR）的组合，有15天的适应期和60天的试验期。屠宰后采集瘤胃内容物和瘤胃上皮样本。饲喂AS增加了瘤胃异丁酸、戊酸、氨氮（NH-N）浓度、脲酶活性和乳头高度（P<0.05），并降低了绵羊的料重比（F:G）、瘤胃细菌蛋白（BCP）、瘤胃乳酸浓度和乳头宽度（P<0.05）。日粮中瘤胃可降解淀粉增加改善了日采食量、平均日增重和瘤胃重量，降低了料重比，并通过降低总氨基酸和NH-N浓度来提高瘤胃氮捕获率，以增加BCP、水通道蛋白3基因和蛋白表达。瘤胃微生物群也发生了变化，因为高瘤胃可降解淀粉日粮降低了Chao指数（P<0.05）。代谢组学分析表明，饲喂AS上调了瘤胃色氨酸代谢和类固醇激素生物合成，而下调了嘌呤代谢、亚油酸代谢和氨基酸生物合成。此外，日粮中瘤胃可降解淀粉增加上调了瘤胃赖氨酸降解和鞘脂代谢，而下调了芳香族氨基酸生物合成。此外，相关性分析结果表明，平均日增重与5-氨基戊酸呈正相关，三种微生物（未分类_f__Selenomonadaceae、Quinella、Christensenellaceae_R-7_group）与绵羊瘤胃异丁酸、戊酸、NH-N浓度、脲酶活性、色氨酸代谢和类固醇激素生物合成呈正相关，与亚油酸代谢和氨基酸生物合成呈负相关
