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

Zinc (Zn) metabolism changes throughout the reproductive cycle of sows to support fetal growth and development and milk production, as found in women.1-3 The underlying physiological processes seem to regulate these adaptations, but other factors, such as dietary Zn concentration, may affect the capacity to adapt. Across species, insufficient dietary Zn intake during gestation and lactation may result in reproductive failure.4-6 In sows, dietary Zn intake may change concentrations of Zn status biomarkers, such as plasma Zn and body-tissue Zn concentrations.7-10 In weaned piglets, plasma Zn concentration was affected by dietary Zn level.11 However, another study in sows showed increased plasma Zn concentrations only when Zn was added to the diet at levels above 500 mg Zn per kg.12,13 Most of the studies in sows that observed changes in plasma Zn concentrations are dated (published between 1967 and 1996), whereas the reproductive capacity of sows increased over time, and these studies used a small number of sows.14 None of these studies evaluated the responses of the cysteinerich protein metallothionein (MT), which is important for absorption and storage of Zn. In addition, these studies each tested only one Zn supplementation level (between 42 and 5000 mg added Zn per kg) against a non-supplemented control group with a dietary Zn concentration between 10 ([semi] purified) and 35 mg Zn per kg to induce Zn deficiency. Furthermore, these studies did not evaluate the pattern of (changing) concentrations throughout gestation and lactation over multiple reproductive cycles. It is therefore unknown whether differences among dietary treatment groups are dependent on the reproductive phase and (or) cycle. Therefore, the objective of the present study was to evaluate the impact of dietary Zn concentration on the profile (concentration and fluctuation) of Zn status biomarkers and performance characteristics in sows over three reproductive cycles. The chosen dietary range covered the array between low (marginal) and maximum allowed dietary Zn concentration in the European Union (maximum 150 mg Zn per kg). This longitudinal study of dietary Zn supplementation was performed on two different floor types during gestation, allowing a broader conclusion across housing conditions