Effects of Zinc Sources on Bioavailability, Production Performance, and Digestibility in Early Lactation of Holstein Dairy Cows

Thirty multiparous Holstein dairy cows used to aim the investigation of the effects of zinc from different sources on bioavailability, production performance, and digestibility. Dairy cows in a complete randomized design randomly allocated to one of five dietary treatments that consist of 1) control (no supplement Zn), 2) Zn glycine complex (ZnGly), 3) Zn Hydroxychloride (ZnHcl), 4) Zn oxide (ZnO), 5) Zn sulfate (ZnSO4). The result indicated that different sources of zinc had not affected glucose, cholesterol and triglyceride (P>0.10). The used of different sources of zinc significantly increased of serum zinc to compare control (P<0.010).  Results showed that, BCS, milk, energy-corrected milk, fat-corrected milk yield and milk yield composition in dairy cows were not significantly affected by Zn source (P>0.10). Somatic cell count tended to decrease in ZnGly (P=0.096) and ZnHcl (P=0.073) in compare of control group. Dry matter intake was not different between treatment (P>0.10). Daily zinc intake, fecal zinc, the zinc concentration in milk per liter/or day, the zinc concentration in milk per liter/or day, apparent absorption and retention of zinc significantly were higher in zinc supplemented group in compare of control (P<0.010). Also, the used of different sources of zinc had not significantly affected on digestibility of dry matter, organic matter, and Ash (P>0.10). Therefore, the results of this study suggested that used of zinc sources in dairy cows diet ZnGly and ZnHcl have higher bioavailability than inorganic sources of zinc and also might improve milk quality throw decrease of somatic cell count.