Effect of Birth Weight on Tissue Copper, Iron, and Zinc Concentrations in Piglets

Abstract Pigs (n = 3,990) were used in a previous study to determine if supplemental zinc fed to sows at various timepoints during gestation would reduce pre-weaning mortality. Additionally, data were analyzed to evaluate the effect of birth weight on tissue concentrations and distribution of copper (Cu), iron (Fe), and zinc (Zn) in piglets. Mixed parity sows were fed 1 of 3 diets: a control corn-soybean meal diet containing 125 ppm supplemental Zn supplied by zinc hydroxychloride, a diet consisting of the control + 141 ppm supplemental Zn as ZnSO4 (266 ppm total supplemental Zn) fed from 5 days after breeding to farrowing, or the control diet fed from breeding to farrowing + 2,715 ppm of supplemental Zn from ZnSO4 (2,840 ppm total supplemental Zn) starting on day 110 of gestation until farrowing. Two low and 2 average birth weight pigs (n = 122) were selected from 10 sows per treatment group to assess Cu, Fe, and Zn concentrations of serum and tails. Serum was collected from each pig at day 1 of age and tails were collected on day 2 of age. Liver tissue was collected from a subset of pigs (n = 65) that died naturally or were euthanized within 2 days of age. The statistical model included fixed effects of treatment and farrowing group, the random effect of their interaction, and the random effect of pig nested within sow. Serum concentrations of each trace element did not differ by birth weight (Table). Low birth weight piglets had greater concentrations of Fe (P = 0.018) and Cu (P = 0.031) in their tails than average birth weight pigs. No differences were observed in tail Zn concentration by birth weight. Notably, pigs that died naturally weighed less at birth than euthanized pigs (P < 0.001). Moreover, pigs that died naturally had greater hepatic Fe concentrations (P < 0.001) and tended to have greater liver Cu concentrations (P = 0.098) compared with euthanized pigs. The associations between tissue iron and copper concentrations and birth weight of piglets may have nutritional and pathophysiological implications and thus warrant further investigation.