Formulating low Zn nursery diets: ABC-4 and other strategies

Pharmacological levels of Zn in early nursery pig diets reduce the instance of post-weaning diarrhea and improve performance. However, there are growing concerns with pharmacological levels of Zn and much attention has been directed toward strategies to lower dietary Zn without negatively impacting performance. Diet acid-binding capacity-4 (ABC-4) could be an option to formulate low Zn diets. Dietary ABC-4 is the hydrochloric acid required to reach a pH of 4. The young pig has a limited capacity to produce enough acid, therefore, incorporation of low ABC-4 ingredients can help maintain an acidic gastric environment and improve health status and subsequent performance. Several ingredients can influence diet ABC-4 such as minerals and acidifiers. However, protein sources utilized in early nursery diets can also impact diet ABC-4. Soy protein sources range in ABC-4 from -13 to 753 meq/kg. In a recent commercial research study, we found no differences between soy sources when ZnO was present in the diet. However, when ZnO was not present, pigs fed a soy protein with low ABC-4 (AX3 Digest) had improved growth performance and lower morbidity and mortality compared to a soy source with high ABC[1]4. Along with dietary ABC-4, several other changes should be considered when zinc oxide is removed from the diet in the areas of management (increased weaning age, sanitation, reducing other stressors), genetics (E coli resistance), water (quality and pH), and nutrition (lower crude protein, increase amino acid ratios relative to lysine, fiber sources, copper inclusion, increased phytase and other enzymes).

Keywords: Zn, acid-binding capacity-4, protein, nursery pigs.