Comparative Effects of Zinc Methionylglycinate and Zinc Sulfate on Hair Coat Characteristics and Zinc Concentration in Plasma, Hair, and Stool of Dogs

Abstract

There are two form of Zn supplement used in commercial dog foods, organic and inorganic forms. These forms can influence Zn absorption and utilization of the animals. The goal of the current study was to evaluate the effects of zinc methionylglycinate (ZnMG) compared to zinc sulfate (ZnSO4) supplementations in commercial dog foods on haircoat characteristics, and Zn concentration in plasma, hair, and stool of the dogs.
Eight mature female beagles were randomly divided into two groups of four dogs each. A Cross-over design was used for this study. The treatments composed of 120 ppm Zn supplement of either ZnMG or ZnSO4. A commercial dry dog food formulated with no Zn supplementation (only from raw materials) was used as the basal diet. Each experimental period lasted 5 wk with the first 2 wk as adaptation period and the last 3 wk as time of Zn supplement. Blood samples were collected for the measurement of serum ALP activity and plasma Zn concentration. Hair was shaved and used to analyze for Zn deposition. Haircoat characteristics were determined under electron microscope. The dogs supplemented with ZnMG had greater hair growth rate, level of Zn deposition in hair, serum ALP activity, amount of Zn absorption (p<0.05), and plasma Zn concentration (p<0.10). The hair of the dogs received ZnMG supplement appeared to be smoother and lesser fragmented than the dogs received ZnSO4 supplement. In conclusion, the organic Zn as ZnMG was found to be the form that could enhance the haircoat characteristics and suitable for supplementation into the commercial dry dog foods.