Effect of Phytase Supplementation on Protein Digestibility in Horses at Maintenance

Abstract

Protein requirements for horses have been widely established, however they can vary based on body condition, age, or activity of the individual horse. They can also vary with the quality of protein which is often determined by its digestibility. Protein digestibility can, in turn, vary with both the amount and type of feed fed. For example, when the dry matter intake or crude protein (CP) concentration increases, apparent protein digestibility increases as well.

Despite established requirements, the feeding of excess protein has become a major environmental and health concern for its role in excess nitrogen emissions. These excess emissions contribute to: pollution of the atmosphere and ground/surface water acidification, eutrophication ecosystem fertilization global warming upper respiratory problems in humans and horses alike

Recent studies have found that that in non-ruminants, phytate, the form in which plant phosphorous is found, develops complexes with amino acids and proteins, thereby reducing their availability to the animal. The addition of phytase, an enzyme that digests phosphorous, to the horse’s diet, therefore, may improve protein digestibility and thereby reduce excess nitrogen emissions into the environment. Performed in correlation with a phosphorous study, this study examined the effects of phytase on protein digestibility in adult horses at maintenance.