Growth performance, immune status, gastrointestinal tract ecology, and function in nursery pigs fed enzymatically treated yeast without or with pharmacological levels of zinc.

Abrupt weaning of pig results in nutritional, environmental, and psychological stresses leading to reduced feed intake, little or no weight gain and in some instances diarrhea, morbidity, and mortality. The post-weaning growth performance lag is often managed by use of antimicrobial growth promoters (AGP), pharmacological levels of trace elements such as zinc oxide (ZnO), specialty feed ingredients, and additives. However, many jurisdictions have already banned, and others are considering banning/restricting use of AGP to abate burgeoning levels of antimicrobial resistance in pathogens of animal and human. The European Union confirmed banning pharmacological ZnO effective June 2022 because of environmental pollution. In this context, identifying alternative nutritional strategies for managing newly weaned pigs is of global concern. Yeast derivatives have been proposed to be beneficial in transitioning piglets. However, there is little available information on comparative efficacy of yeast derivatives and pharmacological ZnO. The current study demonstrated that enzymatically treated yeast (HY40) had positive effects on growth, intestinal histomorphology, nutrient digestibility, and immune indices in nursery pigs. Through differing modes of action, overall growth performance of HY40 piglets was comparable to that of pharmacological ZnO piglets.