Feeding high dietary zinc to gestating sows and implications on sow and piglet performance, their biological responses, and the environment

Abstract

High rates of pre-weaning mortality continue to trouble the swine industry. Feeding high dietary concentrations of zinc (Zn) to sows during late gestation may have utility as a fetal imprinting strategy to positively influence their offspring and mitigate these piglet losses. Supplemental zinc fed in previous experiments were fed in a topdress form that required additional labor. With an aim to determine a practical zinc supplementation approach, a commercial sow study was conducted to investigate the effects of two Zn supplementation methods on sow and piglet performance and piglet mortality. Research in chapter 3 revealed that feeding elevated Zn to sows throughout gestation increased the proportion of pigs born alive, suggesting that elevated gestational Zn intake makes piglets more robust to endure the stresses of farrowing and decreases intrapartum mortality. While supplemental Zn may positively impact piglet performance, the mode through which high Zn acts is unknown. This dissertation aims to investigate three possible modes of action that may explain the influence of zinc on fetal imprinting and ultimately piglet survival. Research presented in chapter 4 indicates that high dietary Zn concentration elicited minimal changes on mineral concentrations of various tissues and serum from sows and piglets. Additionally, elevated Zn fed to sows minimally influenced gene expression of their low birth weight offspring. Research in chapter 5 characterized the effect of high dietary zinc on the microbiome of sows and piglets. Elevated dietary zinc fed to pregnant sows increased prevalence of intestinal bacteria that can be pathogenic in their offspring and favored microbes active in carbohydrate fermentation. Public and governmental concern regarding potential negative impacts of high dietary Zn has increased. Chapter 6 demonstrates that feeding high Zn to gestating sows will increase the amount of Zn excreted. However, the observed performance benefits of feeding high dietary Zn levels may partially offset its negative environmental footprint. This dissertation investigates possible biological mechanisms that high dietary Zn may work through to improve piglet survival and the possible environmental impact of feeding high Zn to gestating sows.