Effect of dietary zinc supplementation on production performance, milk auality, immunity, and blood plasma of dairy cows: A meta-analysis

Abstract

A meta-analysis was conducted to evaluate the effects of Zinc supplementation on production performance, milk quality, immunity, and blood plasma of dairy cows. This study analyzed 25 related articles with 117 data points using a mixed model method with SAS web. The results showed that Zinc supplementation level increased (P<0.05) milk yield and decreased somatic cell count (SCC). Zinc supplementation level also linearly increased (P<0.05) IgM, IgG, and blood zinc. However, it does not have any effect on milk quality and blood biochemistry. In comparison to the control, both organic and inorganic Zinc sources increased (P<0.05) IgG, blood zinc, and decreased (P<0.05) SCC respectively. There was an interaction (P<0.05) observed between Zinc level and source on IgM and blood Zinc concentrations. Organic Zinc produced a higher effect (P<0.05) in increasing IgM and blood Zinc concentration than the inorganic source. It can be concluded that the provision of levels and sources of organic Zinc has a more favorable effect on dairy cows than inorganic Zinc.