Effect of diet on cecal pH and feeding behavior of horses.

Abstract

Three cecal-fistulated horses were used in a 3 × 3 latin square experiment to determine the influence of diet and of cecal infusions of Na2C03 on cecal fermentation and feeding behavior. The three treatments were hay, concentrate and concentrate plus hourly infusions of Na2CO3. Cecal fluid samples and cecal pH readings were taken at zero through 11 hr following feeding at the end of each experimental period, and animal activity was measured by the use of a movie camera set to take 5 sec of film every 5 minutes. Cecal pH was significantly lower at 4, 5 and 6 hr following feeding for the horses receiving the concentrate diet than for those fed hay. The concentrate-fed horses had a significantly lower percentage of cecal acetate and higher cecal propionate than those fed hay, while cecal butyrate was variable for horses receiving both diets. Cecal lactic acid was lower for the horses fed the hay diet than for those fed concentrate but the data were variable. Infusions of Na2CO3 significantly increased cecal pH at 3, 4 and 5 hr post-feeding, compared with that of horses fed only the concentrate diet. Horses receiving the Na2C03 infusion had higher cecal acetate and lower propionate at 1, 3 and 4 hr following feeding than those fed only the all-concentrate diet. The horses fed the concentrate diet spent significantly more time chewing wood and in coprophagy than did those fed hay. Infusions appeared to reduce the time spent in these activities by the concentrate-fed horses, however the differences were not significant. The amount of time spent chewing wood was found to be significantly correlated with cecal propionate.