Effects of European authorised level of zinc from different sources on the physiology and intestinal ecosystem and performance of piglets weaned at different ages

Early weaning can impact piglets' gut health, and some forms of zinc (Zn) may mitigate this stress. This study evaluates the effect of authorised level of Zn, from different sources, on the performance and gut health of piglets weaned at different ages. At weaning (d0), 96 piglets weaned at either 21 (Early, E; 48) or 26 (Normal, N; 48) days were divided into 3 feeding groups: Zn sulphate (SO₄), Zn glycinate (Gly) or a porous form of Zn oxide (Hi) to achieve 150 mg/kg of Zn. On d8 and d21, 8 piglets/group were slaughtered and oxidative status (blood), jejunal morphology, gene expression, microbiota, and volatile fatty acids and intestinal pH were assessed. The N group had a higher body weight throughout the study (<i>P</i> < 0.001) and a higher gain to feed ratio from d7-d14 (<i>P</i> = 0.03). At d8, villus height and villus height:crypt depth ratio (VH:CD) tended to be higher in the N group (<i>P</i> < 0.10). At d8, the Hi diet increased the abundance of the Lactobacillaceae (<i>P</i> = 0.04) in the E piglets. At d21, the Hi tended to increase VH:CD (<i>P</i> = 0.09) compared to SO₄ in N piglets; in the E groups fed SO₄ the crypt depth tended to be higher than Gly and Hi (<i>P</i> < 0.10). Regardless the weaning age, the Gly tended to increase the expression of Glutathione Peroxidase-2 (<i>P</i> = 0.09) and Hi reduced the one of Solute Carrier Family-39 Member-4 (<i>P</i> = 0.07). Weaning age impacted piglets' performance and gut physiology; feeding piglets different forms of Zn may positively improve gut health depending on weaning age.