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Is Nutrient Digestibility Affected by Antibiotic Use in Horses?By Kentucky Equine Research Staff · August 8, 2017

This experiment was designed to test whether chronic administration of sulfamethoxazole and trimethoprim (SMZ) affects digestibility in mature horses.

Four horses were divided into two groups and fed a complete pelleted diet either with or without SMZ for a four-week period. During the last five days of the period, both feed and feces were sampled and analyzed for chemical content.

Chronic SMZ supplementation did not affect the digestibility of any of the nutrients measured in this study. None of the horses showed any signs of digestive upset while receiving the SMZ.

This report of KER's 1993 research was published in Proceedings of the 13th Equine Nutrition and Physiology Society Symposium.

Read the entire research paper, titled Effect of Chronic Administration of the Oral Antibiotic Sulfamethoxazole and Trimethoprim (SMZ) on Digestibility in Mature Horses.