Long-term impact of zinc supplementation in sows : Impact on zinc status biomarkers and performance

Objectives: To evaluate the long-term impact of zinc (Zn) supplementation on performance and Zn status biomarkers in sows and on whether this possible impact depends on housing conditions. Materials and methods: Six groups of sows were allotted to group housing on two different floor types during gestation. Within each group, sows were randomly allocated to one of three diets varying in the amount of Zn supplemented (0, 50, or 100 mg added Zn per kg diet; 50% ZnO: 50% organic Zn) to a basal diet containing 46.6 and 128.9 mg Zn per kg during gestation and lactation, respectively. Blood was collected at days 0, 50, 108, and 143 of every cycle and analyzed for plasma Zn and copper and serum metallothionein (MT) concentrations. After slaughter, mineral concentrations of metacarpals, liver, and abaxial horn wall were determined. Results: Dietary Zn supplementation beyond basal dietary Zn concentrations did not influence serum MT concentrations (P = .77) and Zn concentrations in blood plasma (P = .13), liver (P = .54), bone (P = .26), and horn wall (P = .39). The 100-mg Zn per kg supplemented sows had lower bodyweight, body condition score, and backfat thickness (P < .001). The lack of impact of Zn supplementation may have been (partly) attributed to the unexpected high supply of Zn through premix in the lactation diet. Implications: Under these study conditions, commercially grown sows might not need Zn supplementation during gestation when their basal diet contains Zn with phytase