Purup Stig, Vestergaard Mogens, O Pedersen Lone, Sejrsen Kris
Department of Animal Health, Welfare and Nutrition, Danish Institute of Agricultural Sciences, Research Centre Foulum, PO Box 50, DK-8830 Tjele, Denmark.
J Dairy Res. 2007 Feb;74(1):58-65. doi: 10.1017/S0022029906002093. Epub 2006 Sep 15.
To evaluate the bioactivity of bovine milk from different stages of lactation on human intestinal tissue, a human fetal small intestinal cell line was used as a model system. Milk samples representing six stages of lactation: days 1, 2-3, 6-7 and weeks 12 and 24 after parturition, 1 week before drying off, and milk-like secretion from two stages of the dry period: 7 weeks and 3-4 weeks before expected calving, were collected from 64 Holstein Friesian cows. The whey fraction of the milk or milk-like secretion was added to the culture medium in concentrations ranging from 0.078% to 10%. The growth-promoting activity of whey was measured by determining the incorporation of [3H]thymidine into DNA for the last 24 h of the culture period. Whey fractions from all six stages of lactation stimulated growth of intestinal cells. The growth-promoting activity of colostrum or milk significantly decreased within the first week after calving. The growth-promoting activity in mature milk increased gradually during lactation to reach a level significantly higher than that obtained with colostrum. The growth-promoting activity of whey from milk-like secretion collected after drying off was lower than that of colostrum. Whey from different stages of lactation contained significantly different concentrations of TGF-beta1 (0.5-27 ng/ml) and TGF-beta2 (12-1219 ng/ml). However, neither the differences in TGF-beta1 and TGF-beta2, nor the differences in IGF-I and IGF-binding proteins could fully explain the differences in growth-promoting activity of colostrums or milk from different stages of lactation, suggesting that other factors were also involved. The present study showed that bovine milk contained a number of biologically active components that affected growth and development of human intestinal tissue. The results showed that the growth-promoting activity of colostrum and milk was dependent on the stage of lactation in accordance with previous results obtained with mammary epithelial cells. The changes in growth-promoting activity with stage of lactation were probably related to changes in concentrations of several growth factors.
为了评估不同泌乳阶段的牛乳对人肠道组织的生物活性，使用人胎儿小肠细胞系作为模型系统。从64头荷斯坦弗里生奶牛收集代表泌乳六个阶段的乳样：分娩后第1天、2 - 3天、6 - 7天以及第12周和第24周，干奶前1周，以及干奶期两个阶段的类乳分泌物：预期产犊前7周和3 - 4周。将乳或类乳分泌物的乳清部分以0.078%至10%的浓度添加到培养基中。通过测定培养期最后24小时内[3H]胸苷掺入DNA的情况来测量乳清的促生长活性。来自泌乳所有六个阶段的乳清部分均刺激肠道细胞生长。初乳或乳的促生长活性在产犊后第一周内显著下降。成熟乳中的促生长活性在泌乳期间逐渐增加，达到显著高于初乳的水平。干奶后收集的类乳分泌物的乳清促生长活性低于初乳。来自不同泌乳阶段的乳清含有显著不同浓度的TGF-β1（0.5 - 27 ng/ml）和TGF-β2（12 - 1219 ng/ml）。然而，TGF-β1和TGF-β2的差异以及IGF-I和IGF结合蛋白的差异都不能完全解释不同泌乳阶段初乳或乳促生长活性的差异，这表明还涉及其他因素。本研究表明，牛乳含有许多影响人肠道组织生长和发育的生物活性成分。结果表明，初乳和乳的促生长活性取决于泌乳阶段，这与先前用乳腺上皮细胞获得的结果一致。促生长活性随泌乳阶段的变化可能与几种生长因子浓度的变化有关。
