Animal Nutrition and Physiology Team, AgResearch Grasslands Ltd., Palmerston North 4474, New Zealand; Animal Nutrition Group, Wageningen University and Research, 6700 AH Wageningen, the Netherlands.
Animal Nutrition and Physiology Team, AgResearch Grasslands Ltd., Palmerston North 4474, New Zealand.
J Dairy Sci. 2020 May;103(5):4754-4764. doi: 10.3168/jds.2019-17529. Epub 2020 Mar 18.
The development of the small intestine (SI) is important for the health and growth of neonatal calves. This study evaluated the effect of arginine (Arg) and glutamine (Gln) supplementation and 2 levels of milk allowance on the histomorphological development of the SI in preweaning calves. Sixty mixed-sex Friesian × Jersey calves (3-5 d of age) were offered reconstituted whole milk (125 g/L, 26% fat, 26% protein) at either high (20% of arrival body weight/d; HM) or low (10% of arrival body weight/d; LM) milk allowance without (Ctrl) or with supplementary Arg or Gln (at 1% of milk dry matter) in a 2 × 3 factorial design (n = 10/treatment). After 35 d on the diets, all calves were slaughtered to collect tissues for examination of SI development. Calves in the HM group had higher milk intake, total weight gain, and average daily gain compared with LM calves, but no effect of AA supplementation nor an interaction between milk allowance and AA supplementation was observed. For the duodenum, we observed an AA by milk allowance interaction for villus height and width, and goblet cell number per villus (HM-Arg > HM-Gln > HM-Ctrl), and villus height to crypt depth ratio (HM-Arg > HM-Gln = HM-Ctrl), but no effect of AA supplementation in the LM group. Goblet cell numbers per 100 µm of SI were greater in Arg-supplemented calves than in unsupplemented controls, with Gln-supplemented calves intermediate to but not different from the other groups. Epithelium thickness was greater in LM than in HM calves. Villus density, crypt depth, and muscle thickness did not differ between groups. For the jejunum, there was an AA by milk allowance interaction for villus height, villus surface area, and villus height to crypt depth ratio (HM-Arg = HM-Gln > HM-Ctrl), with no effect of AA supplementation in the LM groups. Amino acid supplementation affected goblet cell number per villus (HM-Gln > HM-Ctrl calves, HM-Arg intermediate), and both LM-Arg and LM-Gln calves had greater numbers than LM-Ctrl calves. Villus width, crypt depth, and muscle thickness were greater in HM than LM calves but there was no effect of AA supplementation. Villus density, goblet cell number per 100 µm of SI, and epithelium thickness were unaffected by AA supplementation and milk allowance. Milk allowance and AA supplementation had no effect on SI morphology in the ileum. Increasing milk allowance improved villus height, width, and surface area but only in Arg- or Gln-supplemented calves, not in control calves. The observed changes in development may be important for intestinal functionality, integrity, and barrier function in preweaning calves, potentially through increased cell growth and proliferation or reduced levels of cellular atrophy.
小肠（SI）的发育对于新生牛犊的健康和生长很重要。本研究评估了精氨酸（Arg）和谷氨酰胺（Gln）补充以及 2 种牛奶供应水平对断奶前小牛 SI 组织形态发育的影响。60 头混合性别弗里斯兰×泽西牛（3-5 日龄）接受再配制的全脂牛奶（125g/L，26%脂肪，26%蛋白质），高（到达体重的 20%/d；HM）或低（到达体重的 10%/d；LM）牛奶供应，不添加（Ctrl）或添加精氨酸或谷氨酰胺（占牛奶干物质的 1%），采用 2×3 因子设计（n=10/处理）。在饮食上 35 天后，所有小牛均被屠宰以收集组织以检查 SI 发育情况。与 LM 小牛相比，HM 组小牛的牛奶摄入量、总增重和平均日增重更高，但 AA 补充或牛奶供应与 AA 补充之间没有相互作用。对于十二指肠，我们观察到 AA 与牛奶供应之间存在绒毛高度和宽度、每个绒毛的杯状细胞数和绒毛高度与隐窝深度比的互作（HM-Arg>HM-Gln>HM-Ctrl），但 LM 组 AA 补充没有影响。与未补充对照组相比，补充 Arg 的小牛的 SI 中每个 100 µm 的杯状细胞数更多，而补充 Gln 的小牛则处于中间水平，但与其他组无差异。LM 小牛的上皮厚度大于 HM 小牛。绒毛密度、隐窝深度和肌肉厚度在各组之间无差异。对于空肠，绒毛高度、绒毛表面积和绒毛高度与隐窝深度比存在 AA 与牛奶供应的互作（HM-Arg=HM-Gln>HM-Ctrl），但 LM 组的 AA 补充没有影响。AA 补充影响每个绒毛的杯状细胞数（HM-Gln>HM-Ctrl 小牛，HM-Arg 居中），并且 LM-Arg 和 LM-Gln 小牛的数量均大于 LM-Ctrl 小牛。HM 小牛的绒毛宽度、隐窝深度和肌肉厚度大于 LM 小牛，但 AA 补充没有影响。绒毛密度、SI 中每个 100 µm 的杯状细胞数和上皮厚度不受 AA 补充和牛奶供应的影响。SI 形态在回肠中不受牛奶供应和 AA 补充的影响。增加牛奶供应可改善绒毛高度、宽度和表面积，但仅在 Arg 或 Gln 补充的小牛中，而不是在对照组小牛中。发育过程中的这些变化可能对断奶前小牛的肠道功能、完整性和屏障功能很重要，可能通过增加细胞生长和增殖或降低细胞萎缩水平来实现。
