title: Biological activity of bovine milk on proliferation of human intestinal cells.
abstract: 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.
authors.affiliation: Department of Animal Health, Welfare and Nutrition, Danish Institute of Agricultural Sciences, Research Centre Foulum, PO Box 50, DK-8830 Tjele, Denmark. stig.purup@agrsci.dk
authors.forename: Stig
authors.initials: S
authors.lastname: Purup
authors.forename: Mogens
authors.initials: M
authors.lastname: Vestergaard
authors.forename: Lone
authors.initials: L
authors.lastname: O Pedersen
authors.forename: Kris
authors.initials: K
authors.lastname: Sejrsen
mesh_terms: D000818:Animals; D002417:Cattle; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D005260:Female; D006801:Humans; D007422:Intestines / Q000166:cytology*; D007774:Lactation; D008892:Milk / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D016212:Transforming Growth Factor beta