College of Animal Science, Inner Mongolia Agricultural University, Hohhot, China.
J Anim Sci. 2024 Jan 3;102. doi: 10.1093/jas/skae188.
The present study aimed to investigate the impact of initiating alfalfa supplementation at either 14 d or 42 d of age on growth performance, blood parameters, rumen tissue gene expression, and epithelial microbiota in pre-weaning lambs. A total of 42 seven-day-old male Hu lambs (3.88 ± 0.92 kg) were selected for this study. After 7 d of adjustment period, 6 lambs were slaughtered at 14 d of age to establish a baseline control. The remaining 36 lambs were randomly allocated to 2 treatment groups, every 3 lambs were considered a unit, including fed milk replacer, starter pellets, and either alfalfa hay fed at 14 (EAF) or 42 d of age (LAF). Body weight and feed intake were recorded for lamb until 70 d of age. Blood samples, rumen tissue samples, and epithelial microbiota samples were collected from the lambs at 42, 56, and 70 d of age. The results indicated that average daily gain, starter intake, and total dry matter intake were greater in the EAF group compared to the LAF group from 14 to 42 d of age (P < 0.01), but no significant differences from 43 to 70 d of age or during the entire trial. Treatment and age interactively affected the alfalfa intake (P = 0.02) from 43 to 70 d of age. The concentration of serum immunoglobulin A (IgA) (P < 0.01) and the expression of the rumen gene insulin-like growth factor-1 (P < 0.01) were greater in the EAF group compared to the LAF group at 42 d of age. Furthermore, the concentrations of alkaline phosphatase (P = 0.03), albumin (P < 0.01), total protein (P = 0.03), urea (P = 0.04), lipopolysaccharide (P < 0.01), β-hydroxybutyric acid (P = 0.02), interleukin-1β (IL-1β) (P < 0.01), IL-4 (P < 0.01), and tumor necrosis factor-α (P < 0.01) were affected by age. The abundance of Prevotella was lower (P < 0.05), whereas Megasphaera (P < 0.05) was greater in the EAF group compared to the LAF group at 42 d of age. The early addition of alfalfa promotes rumen epithelial microbiota colonization. In conclusion, this study demonstrated that alfalfa provision at 14 d of age promotes growth performance in lambs, but this effect disappeared at 43 to 70 d of age. Moreover, provision of alfalfa at 14 d of age enhances the immune response, promotes rumen tissue cell proliferation, and affects dynamical changes of rumen epithelial microbiota. Meanwhile, our findings showed that the rumen undergoes significant physiological challenges during the transition from a liquid diet to a solid diet.
本研究旨在探讨在羔羊 14 日龄或 42 日龄时开始添加紫花苜蓿对其生长性能、血液参数、瘤胃组织基因表达和上皮微生物群的影响。共选择了 42 只 7 日龄雄性湖羊（3.88±0.92kg）进行本研究。在 7 天的调整期后，6 只羔羊在 14 日龄时被屠宰以建立基线对照。其余 36 只羔羊随机分配到 2 个处理组，每组 3 只羔羊为一个单位，包括饲喂代乳料、开食料和在 14（EAF）或 42 日龄（LAF）时饲喂的紫花苜蓿干草。在 70 日龄前记录羔羊的体重和采食量。在 42、56 和 70 日龄时从羔羊采集血液样本、瘤胃组织样本和上皮微生物群样本。结果表明，从 14 日龄到 42 日龄，EAF 组的平均日增重、开食料采食量和总干物质采食量均高于 LAF 组（P<0.01），但从 43 日龄到 70 日龄或整个试验期间没有差异。处理和年龄交互影响从 43 日龄到 70 日龄的紫花苜蓿采食量（P=0.02）。EAF 组羔羊在 42 日龄时血清免疫球蛋白 A（IgA）浓度（P<0.01）和瘤胃基因胰岛素样生长因子-1（P<0.01）的表达均高于 LAF 组。此外，碱性磷酸酶（P=0.03）、白蛋白（P<0.01）、总蛋白（P=0.03）、尿素（P=0.04）、脂多糖（P<0.01）、β-羟丁酸（P=0.02）、白细胞介素-1β（IL-1β）（P<0.01）、白细胞介素-4（IL-4）（P<0.01）和肿瘤坏死因子-α（TNF-α）（P<0.01）的浓度受年龄影响。与 LAF 组相比，EAF 组在 42 日龄时普雷沃氏菌的丰度较低（P<0.05），而巨球形菌的丰度较高（P<0.05）。早期添加紫花苜蓿促进了瘤胃上皮微生物群的定植。综上所述，本研究表明，在 14 日龄时添加紫花苜蓿可促进羔羊的生长性能，但这种效果在 43 日龄到 70 日龄时消失。此外，在 14 日龄时添加紫花苜蓿可增强免疫反应，促进瘤胃组织细胞增殖，并影响瘤胃上皮微生物群的动态变化。同时，我们的研究结果表明，瘤胃在从液体饲料向固体饲料过渡期间经历了显著的生理挑战。
