Honors Thesis Number

UHON 499-719


Animal Science-Equine Science

Faculty Advisor

Venable, Erin


Little is known about the effect of exercise on the microbial profile of the equine cecum. As hindgut fermenters, horses are particular sensitive to gastrointestinal disorders. Previous work (McKenzie et.al., 2010; Walshe and Duggan, 2011; Schoester et.al., 2012; and Jager et.al., 2013) has demonstrated an impact of exercise on the fecal microbial composition of equines and canines. However, no information has been reported on the effects of exercise related to ammonia and volatile fatty acid production within the cecum. The objective of this research was to test the hypothesis that increasing exercise would impact the production of ammonia and volatile fatty acids within the cecum. Four cecally-cannulated horses were used in a Latin square 4x4 to investigate the effect of increasing levels of exercise on cecal metabolites. Four exercise treatments (1 = no exercise; 2 = 5 minutes trot; 3 = 15 minutes trot; 4 = 20 minutes trot) were applied to test our hypothesis. Exercise was conducted by lunging with trained handlers. All horses were fed to maintain body condition score (BCS) = 5 ±1 and were weighed weekly with mean BW of 521 kg ± 24 kg. Each horse was given daily turnout for 8 ± 1 hrs and were stalled overnight in identical 3 x 4 meter stalls with ad lib access to water, salt, and 2.27 kg of mixed grass hay. Horses were fed pelleted complete grain (Strategy® Purina Mills, St. Louis, Missouri) twice daily at approximately 6:30 AM and 4:00 PM. Cecal samples were collected, each period, on day 1 prior to exercise and on day 7 following exercise. Data were analyzed using Proc Mix of SAS (v9.4 SAS Institute, Inc.) with significance established at (P < 0.05). Chemical analysis of cecal contents demonstrated no significant difference in ammonia or volatile fatty acid concentration across treatments. Further work should investigate the impacts of longer and more frequent exercise periods with greater intensity.