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Interpretive Summary: Effect of bis-glycinate bound zinc or zinc sulfate on zinc metabolism in growing lambs

By Anne Zinn

Zinc is required for optimal animal health and production, but feedstuffs often do not contain enough zinc to meet the requirement of animals, which means livestock are often provided supplemental zinc. Several sources of supplemental zinc are available, including inorganic and organic sources, and previous research has sought to compare the bioavailability of different zinc sources. To date, little research has been conducted utilizing bis-glycinate bound zinc.

A paper recently published in the Journal of Animal Science aimed to assess the bioavailability of bis-glycinate zinc compared with ZnSO4 based on apparent absorption and retention of zinc by lambs. Additionally, the team aimed to determine the effects of supplemental zinc source on nutrient digestibility, plasma, and tissue trace mineral concentrations, as well as gene expression of proteins involved in zinc transport and storage. It was believed that bis-glycinate zinc would be more bioavailable than ZnSO4, resulting in greater zinc retention by lambs supplemented with the organic zinc source.

Results of the present study demonstrated that zinc apparent absorption and retention were not affected by supplemental zinc source and that lambs supplemented with bis-glycinate bound zinc had greater concentrations of zinc in circulation and liver expression of metallothionein-1, which is a key regulator of zinc homeostasis. Overall, results suggest that zinc from 15 mg supplemental Zn/kg dry matter as bis-glycinate bound zinc is more available for biological processes than zinc from 15 mg supplemental Zn/kg dry matter as zinc sulfate. Further research is necessary to better understand post-absorptive metabolism of bis-glycinate bound zinc and the effects of this zinc source on immune function and growth performance of livestock.

The full paper can be found on the Journal of Animal Science webpage.