Effects of chelated Zinc or Copper on Ruminal fermentation characteristics and milk production in lactating holstein COWS

This study was conducted to examine the effects of supplemental Zn or Cu chelated with methionine or sulfate on ruminal fermentation, milk yield, milk composition and Immunoglobluin G (IgG) concentration in the blood of lactating Holstein cows. In this experiment, five Holstein daily cows with permanent ruminal cannulae were subjected to five dietary treatments comprising either sulfate or methionine chelated Zn or Cu in a Total Mixed Ration (TMR) in a 5×5 Latin Square experimental design. The five dietary treatments were control, 40 ppm Dry Matter Intake (DMI)^-1 of Cu-Sulfate (CuS), 20 ppm DMI^-1 of Cu-Methionine (CuMet) and 200 ppm DMI^-1 of Zn-Sulfate (ZnS) and finally 100 ppm DMI-1 of Zn-Methionine (ZnMet) chelate. Ruminal fermentation patterns including pH, ammonia-N and VFA post-feeding were significantly altered when animals were supplemented with chelated minerals relative to the control (p<0.05). In terms of animal performance, DMI (averaging 25.7 kg day^-1) did not differ among the dietary treatments whereas milk yield increased (p<0.05) upon supplementation of chelated trace minerals compared to control and was the highest in cows fed ZnMet. Somatic cell counts were much lower (p<0.05) in animals supplemented with chelated Zn than chelated Cu. The immune response as determined by the plasma IgG concentration of increased (p<0.05) in all cows supplemented with chelated Zn or Cu compared to control. The results of the study demonstrate that chelated trace mineral complexes are of use to improve animal performance and immune responses at lower or similar levels in comparison to non-chelated minerals although, further investigations are necessary to identify the modes of action and intestinal absorption rate.