Lay Summary Zinc is an essential micromineral for pigs, playing a critical role in various physiological reactions. Although multiple nutritional guides provide recommendations for dietary zinc, the swine industry commonly uses higher dietary zinc levels to improve growth performance in post-weaning diets, a practice that has been increasingly questioned in multiple countries. Developing nutritional and management strategies to reduce zinc use requires a deep understanding of the factors influencing zinc excretion and user-friendly tools to quantify the excretion. This meta-analysis analyzed data from 51 published studies using two statistical approaches to identify nutritional factors associated with zinc excretion and develop predictive models for fecal zinc excretion. Whereas factors such as high concentrations of certain minerals, nitrogen, fiber, lactose, the use of dietary enzymes, and zinc sources can influence zinc excretion, zinc intake is the major determinant of excretion. Models derived from the review of the literature indicate that when pigs are fed at or below their zinc requirement estimate, 64% of the zinc is excreted in feces. However, when pigs are fed above their requirement estimates, zinc excretion increases to 82% of intake.
Arroyave et al. (Wed,) studied this question.