Effect of different levels of inorganic, nano and organic Zn on Zn absorption, microbial protein, metabolites and immunoglobulins of blood and colostrum in ewes and their lambs

In this study, the effect of different levels of ZnO, nano-ZnO and Zn-methionine, in pre- and post-partum diets, on feed intake, Zn absorption, microbial protein, as well as metabolites and IgG, IgM and IgA in the blood and colostrum of ewes and suckling lambs were investigated. Experiment was conducted from 50 days before to 30 days after lambing. Sixty pregnant Khorasan-Kurdish ewes were divided into six experimental groups (10 replicates) in a randomized complete block design. Experimental diets contained ZnO, nano-ZnO and Zn-methionine to meet NRC recommendation, or higher than NRC-recommended level. Replacing ZnO with nano-ZnO or Zn-methionine had no effect on different variables in ewes, but increasing Zn level in the diet of ewes resulted in an increment of daily Zn intake, a decline of Zn absorption coefficient and an increase of fecal Zn excretion (P<0.05). Feeding mother ewes with different Zn sources had no effect on blood metabolites and immunoglobulins of the suckling lambs. Overall, nano-ZnO had no positive or negative effects on ewes and suckling lambs and using Zn-methionine instead of ZnO did not improve the metabolic condition of the animals. On the other hand, the increasing dietary Zn concentration increased zinc excretion in the environment. In practice, using the conventional ZnO at the NRC recommendation level is sufficient to provide the requirement, and to maintain the immunity of pre- and post-partum ewes and there is no need for additional Zn from other sources.