College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China.
College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China; Qinghai Academy of Animal Science and Veterinary Medicine, Xining, Qinghai, China.
Animal. 2021 Mar;15(3):100019. doi: 10.1016/j.animal.2020.100019. Epub 2021 Feb 17.
The caecum is the primary site where microbial fermentation and acidosis occurred. The supplementation of starter feed and alfalfa hay has the potential to influence caecal microbiota and then affect caecal fermentation. This study aims to investigate the effect of starter feed and alfalfa hay supplementation on caecal microbiota, immune homeostasis, and growth of preweaning yaks. Twenty 30-day-old male yak calves were randomly assigned to four groups, which separately fed with milk replacer (CON group), milk replacer with alfalfa hay (A group), milk replacer with starter feed (S group), and milk replacer with starter feed plus alfalfa hay (SA group) throughout the trial. Growth performance and plasma physiological and biochemical indicators were measured every 30 days. Calves were sacrificed at 120 days of age. The caecal contents were collected for measuring pH and contents of volatile fatty acids (VFAs) and lipopolysaccharide (LPS) and for characterizing caecal microbiota. The results indicated that individual or simultaneous supplementation with alfalfa hay and starter feed all significantly increased the BW, body height, body length, and chest girth of yak calves. However, supplementation with starter feed significantly increased plasma cortisol, nitric oxide, tumor necrosis factor-α, and interferon-γ concentrations and the ratio of aspartate aminotransferase to alanine aminotransferase of yak calves when compared with the control and alfalfa hay feeding groups, while the co-supplementation of starter feed and alfalfa hay could significantly decrease these inflammation-related indices when compared with the starter feeding group. Sequencing of the 16S rRNA gene showed that starter feed and alfalfa hay separately stimulated the proliferation of starch-decomposing and cellulose- or hemicellulose-decomposing bacteria. This also significantly increased the levels of acetate, propionate, butyrate, valerate, isobutyrate, and isovalerate in the caecal contents. Furthermore, compared with the S and CON groups, the significantly increased genera of Desulfobulbus, Olsenella, Pseudoflavonifractor, and Stomatobaculum in the SA and A groups were beneficial to the immune homeostasis, and the significantly decreased Blautia, Clostridium IV, Bacteroides, Eubacterium, Clostridium XVIII, and Mogibacterium in the SA and A groups were related to the reduced caecal lactate and LPS contents, the decreased inflammatory reaction, and the improved healthy hepatic condition of yak calves. In conclusion, milk replacer supplemented with alfalfa hay and starter feed is recommended during preweaning to improve yak calf health and growth because this regimen promotes the growth and maintains the immune homeostasis of yak calves.
盲肠是微生物发酵和酸中毒发生的主要部位。补充基础饲料和苜蓿干草有可能影响盲肠微生物群，进而影响盲肠发酵。本研究旨在探讨基础饲料和苜蓿干草补充对断奶前牦牛盲肠微生物群、免疫稳态和生长的影响。20 头 30 日龄雄性牦牛犊随机分为四组，分别用代乳料（CON 组）、代乳料加苜蓿干草（A 组）、代乳料加基础饲料（S 组）和代乳料加基础饲料加苜蓿干草（SA 组）进行试验。每隔 30 天测量一次生长性能和血浆生理生化指标。犊牛于 120 日龄处死。收集盲肠内容物，测定 pH 值和挥发性脂肪酸（VFAs）和脂多糖（LPS）含量，并对盲肠微生物群进行特征分析。结果表明，单独或同时补充苜蓿干草和基础饲料均显著提高了牦牛犊的 BW、体高、体长和胸围。然而，与对照组和苜蓿干草喂养组相比，补充基础饲料显著增加了牦牛犊的血浆皮质醇、一氧化氮、肿瘤坏死因子-α和干扰素-γ浓度以及天冬氨酸氨基转移酶与丙氨酸氨基转移酶的比值，而同时补充基础饲料和苜蓿干草可显著降低与基础饲料喂养组相比，这些与炎症相关的指标。16S rRNA 基因测序显示，基础饲料和苜蓿干草分别刺激淀粉分解菌和纤维素或半纤维素分解菌的增殖。这也显著增加了盲肠内容物中乙酸、丙酸、丁酸、戊酸、异丁酸和异戊酸的水平。此外，与 S 组和 CON 组相比，SA 组和 A 组中脱硫孤菌、奥尔森菌、拟杆菌和 Stomatobaculum 的显著增加属有利于免疫稳态，SA 组和 A 组中 Blautia、梭菌 IV、拟杆菌、真杆菌、梭菌 XVIII 和莫格比菌的显著减少与盲肠乳酸和 LPS 含量降低、炎症反应减轻以及牦牛犊健康肝脏状况改善有关。综上所述，建议在断奶前用代乳料补充苜蓿干草和基础饲料，以提高牦牛犊的健康和生长，因为这种方案促进了牦牛犊的生长并维持了其免疫稳态。
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