부산대학교 도서관

This study evaluated the impact of different dietary zinc/copper ratios on the gene expression of zinc (Zn), copper (Cu), and iron (Fe) transporters in jejunum and liver of weaned pigs. Piglets (n = 160) were weaned at 21 days of age (d 21; 7.81 ± 0.25 kg) and fed a basal post-weaning diet (without antibiotics) supplemented (n = 40/treatment) with 100 (LZn) or 3,000 (HZn) mg/kg of Zn as ZnO in combination with 6 (LCu) or 130 (HCu) mg/kg of Cu as CuSO4 until d 42. Piglets were sacrificed at d 21, d 28, d 35, and d 42 (n = 10 animals∙treatment -1∙day-1) for harvesting jejunum and liver samples. The mRNA expression of Zn, Cu, and Fe transporters was evaluated by quantitative real-time PCR. Data were analyzed using a 2x2x3 factorial design (two Zn levels, two Cu levels, and three slaughter days) and results are presented as fold-change relative to pre-treatment values (d 21). For Zn-related genes, jejunum Zip4 expression was least for HZn from d 28 (Zn effect; P≤ 0.01; Table 1) and Zip5 was greatest for HZn at d 28 (Zn effect; P= 0.04). On d 42, the greatest values for jejunal Zip4 were observed with LZnHCu (interaction Zn x Cu x time; P= 0.05). For Znt1 in jejunum and liver, mRNA expression was greatest for HZn from d 28 (Zn effect; P≤ 0.01) whereas Zip5 was greatest in liver for HZn at d 28 and d 35 (Zn effect; P≤ 0.04). On d 35, the least values for hepatic Zip5 were observed with LZnHCu (interaction Zn x Cu x time; P= 0.04). For Cu-related genes, no treatment effect (P≥ 0.12) was detected for Crt1 and Atox1 in jejunum and liver. In both tissues, Mt3 expression was greatest for HZn from d 28 (Zn effect; P≤ 0.01). No treatment effect was detected (P= 0.53) for Atp7a expression in jejunum. However, for Atp7b in liver, values were greatest for HZn from d 35 (Zn effect; P≤ 0.01). For Fe-related genes, no treatment effect (P≥ 0.18) was detected for Heph, Tfrc and Fpn1 in jejunum and for Dmt1, Tfrc and Hamp in liver. In jejunum, Dmt1 was greatest for LZn at d 28 and d 42 (Zn effect; P≤ 0.01) whereas Fth1 was greatest in HZn groups from d28 (Zn effect; P ≤ 0.01) and for HCu at d42 (Cu effect; P= 0.04). In liver, Fth1 and Fpn1 were greatest for HZn from d28 (Zn effect; P≤ 0.02). In conclusion, among the present different dietary zinc/copper ratios, most treatment effects on intestinal and hepatic Zn, Cu and Fe transporters originated from dietary ZnO levels suggesting a major contribution of Zn in modulating the metabolism of these trace minerals in post-weaning piglets.