title: Dietary supplementation with zinc oxide increases Igf-I and Igf-I receptor gene expression in the small intestine of weanling piglets.
abstract: This study was conducted to investigate the mechanism for the effect of elevated levels of dietary zinc oxide (ZnO) in enhancing the intestinal growth of weanling piglets. In Experiment 1, 4-wk-old (8.1 +/- 0.6 kg) crossbred barrows (n = 36) were assigned randomly to 1 of the 2 dietary groups, with 6 pens/group (3 pigs/pen). One group was fed the basal diet containing 100 mg Zn/kg diet. The other group was fed the basal diet supplemented with ZnO to provide 3000 mg Zn/kg diet. Pigs consumed their feed ad libitum for 14 d. In Experiment 2, 4-wk-old (7.6 +/- 0.16 kg) crossbred barrows (n = 16) were housed individually and assigned to 1 of the 2 dietary groups (8 pigs/group) as in Experiment 1, except that the 2 groups were pair-fed the same amount of feed. At the end of a 14-d treatment period, all of the pigs in both Experiments 1 and 2 were weighed, feed consumption was measured, and blood samples were collected for assays of insulin-like growth factor-I (IGF-I). In addition, 1 pig from each pen in Experiments 1 and 2 was selected randomly to obtain the small-intestinal mucosa for analyzing IGF-I and IGF-I receptor (IGF-IR) gene expression and to determine the small-intestinal morphology. In Experiment 1, dietary supplementation of ZnO increased (P < 0.05) the daily body weight gain and daily feed intake. In Experiment 2, dietary supplementation of ZnO increased (P < 0.05) the daily body weight gain and feed conversion efficiency. In both experiments, the villous height of the small-intestinal mucosa and both the mRNA and protein levels for IGF-I and IGF-IR in the small intestine were markedly enhanced (P < 0.05) by feeding elevated levels of Zn. Serum IGF-I levels did not differ between the control and Zn-supplemental groups in either experiment. Collectively, these results suggest that dietary Zn supplementation exerts its beneficial effects on the intestinal growth of weanling piglets through increasing IGF-I and IGF-IR expression in the small-intestinal mucosa.
authors.affiliation: National Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, P. R. China.
authors.forename: Xilong
authors.initials: X
authors.lastname: Li
authors.forename: Jingdong
authors.initials: J
authors.lastname: Yin
authors.forename: Defa
authors.initials: D
authors.lastname: Li
authors.forename: Xingjie
authors.initials: X
authors.lastname: Chen
authors.forename: Jianjun
authors.initials: J
authors.lastname: Zang
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhou
mesh_terms: D000818:Animals; D004032:Diet; D005786:Gene Expression Regulation / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D017526:Receptor, IGF Type 1 / Q000187:drug effects* / Q000235:genetics; D013552:Swine; D014886:Weaning; D015034:Zinc Oxide / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1; D015034:Zinc Oxide