Schottstedt T, Muri C, Morel C, Philipona C, Hammon H M, Blum J W
Division of Nutrition and Physiology, Institute of Animal Genetics, Nutrition and Housing, Vetsuisse Faculty, University of Berne, CH-3012 Berne, Switzerland.
J Dairy Sci. 2005 Mar;88(3):1050-61. doi: 10.3168/jds.S0022-0302(05)72773-9.
Circulating levels of vitamin A (retinol) and lactoferrin (Lf) are low in calves at birth. Bovine colostrum contains relatively high amounts of vitamin A and Lf, and both substances are intestinally absorbed by neonatal calves. There is evidence that these compounds interact with insulin-like growth factor binding proteins and thus influence the status and effects of insulin-like growth factor. The hypothesis was therefore tested that vitamin A and Lf influence epithelial growth, development, and absorptive capacity of the small and large intestine and modulate intestinal immune tissues (Peyer's patches; PP). Four groups of calves (n = 7 per group) were fed a milk-based formula with or without vitamin A and (or) Lf. Group F received formula (F) only; group F(A) was fed F supplemented with vitamin A; group F(L) was fed F supplemented with Lf, and group F(AL) received F plus vitamin A plus Lf. An additional group of calves (group C; n = 7) served as positive control and was fed colostrum (C) from pooled milk obtained on d 1, 2, and 3 of lactation. Amounts of nutritive components in formula and colostrum were similar. Blood samples were taken to measure vitamin A and Lf, and plasma xylose (added on d 4 to feeds) was measured postprandially for 8 h as a marker of intestinal absorptive capacity. Plasma vitamin A was low at birth and further decreased in groups F and F(L), but increased in groups F(A), F(AL), and C. Plasma Lf was low at birth and transiently increased up to 4 h after the first meal in group C. Xylose absorption was higher in group C than in other groups. Incorporation of 5-bromo-2'-deoxyuridine into DNA (as a measure of cell proliferation rate) was enhanced in intestinal crypts in groups F and F(L) at all intestinal sites. Ileum villus heights of groups F and F(L) were smaller than of groups F(A) and F(AL). Villus height to crypt depth ratios were smaller in F-fed groups (especially in groups F and F(L)) than in C-fed calves in the duodenum and jejunum. Incorporation of 5-bromo-2'-deoxyuridine into colon crypt cells of group F was greater than in groups F(L) and F(A). Sizes of follicles of PP in the ileum were greater in group F(A) than in group F. In the ileum, vitamin A and Lf tended to interact with PP size. In conclusion, feed supplementation of vitamin A and Lf influenced growth of the ileum and colon. Interactions were observed between vitamin A and Lf on epithelial cell maturation, villus growth, and size of follicles in PP of neonatal calves.
出生时犊牛体内维生素A（视黄醇）和乳铁蛋白（Lf）的循环水平较低。牛初乳中含有相对大量的维生素A和Lf，这两种物质均可被新生犊牛肠道吸收。有证据表明，这些化合物与胰岛素样生长因子结合蛋白相互作用，从而影响胰岛素样生长因子的状态和作用。因此，对维生素A和Lf影响小肠和大肠上皮生长、发育及吸收能力并调节肠道免疫组织（派伊尔氏淋巴集结；PP）这一假说进行了验证。四组犊牛（每组n = 7头）分别饲喂添加或不添加维生素A和（或）Lf的乳基配方奶。F组仅饲喂配方奶（F）；F（A）组饲喂添加维生素A的F；F（L）组饲喂添加Lf的F，F（AL）组则饲喂F加维生素A加Lf。另一组犊牛（C组；n = 7头）作为阳性对照，饲喂分娩第1、2和3天采集的混合初乳（C）。配方奶和初乳中的营养成分含量相似。采集血样测定维生素A和Lf，并在餐后8小时测定血浆木糖（第4天添加到饲料中），作为肠道吸收能力的指标。出生时血浆维生素A水平较低，在F组和F（L）组中进一步下降，但在F（A）组、F（AL）组和C组中升高。出生时血浆Lf水平较低，C组在首次进食后4小时内短暂升高。C组的木糖吸收高于其他组。F组和F（L）组在所有肠道部位的肠隐窝中，5-溴-2'-脱氧尿苷掺入DNA（作为细胞增殖率的指标）均增强。F组和F（L）组的回肠绒毛高度低于F（A）组和F（AL）组。在十二指肠和空肠中进食F组（尤其是F组和F（L）组）的绒毛高度与隐窝深度之比小于进食C组的犊牛。F组结肠隐窝细胞中5-溴-2'-脱氧尿苷的掺入量大于F（L）组和F（A）组。F（A）组回肠中PP的滤泡大小大于F组。在回肠中，维生素A和Lf倾向于与PP大小相互作用。总之，饲料中添加维生素A和Lf影响回肠和结肠的生长。在新生犊牛的上皮细胞成熟、绒毛生长及PP滤泡大小方面，观察到维生素A和Lf之间存在相互作用。
