In the current study, ZnPro and ZnO increased serum IgM and IgG concentrations in calves at 14 days of age, and ZnPro also elevated IgM concentration at 28 days of age, which adds one more biological advantage to ZnPro, as IgM is considered the first line of host defense against infections and also plays an important role in immune regulation and immunological tolerance [26]. This evidence concerns the gene CD40LG and infection.