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

The study investigates the impact of different diets and the addition of sodium bicarbonate on the digestive processes and feeding behaviors of horses. The experiment presented that the diet type influences the cecal pH levels and the composition of cecal fermentation products in horses, as well as certain behaviors like wood chewing and coprophagy.

Study Design and Methodology

• Three horses were involved in the experiment constructed based on a 3×3 Latin square setup. The horses had previously undergone a surgical procedure to establish a cecal fistula, an artificial permanent opening into the cecum.
• Three different treatments were administered to the horses: hay diet, concentrate diet, and concentrate diet along with hourly infusions of sodium bicarbonate (Na2CO3).
• Cecal fluid samples were collected and cecal pH measurements taken at hourly intervals from zero to eleven hours post-feeding at the end of each experimental period.
• Animal behavior was closely monitored using a movie camera set to take 5 seconds of film every 5 minutes.

Findings on Cecal pH and Fermentation

• Horses on the concentrate diet had significantly lower cecal pH levels at 4, 5, and 6 hours post-feeding than those fed on hay.
• Concentration of cecal acetate was lower, while cecal propionate was higher in horses fed the concentrate diet as compared to those fed hay. The level of cecal butyrate was found to be variable for both diets.
• Horses in the hay group exhibited lower cecal lactic acid levels than the concentrate group, however, the data were inconsistent across samples.

Impact of Sodium Bicarbonate Infusion

• Infusion of sodium bicarbonate (Na2CO3) significantly increased the cecal pH at 3, 4, and 5 hours post-feeding, when compared to horses fed only the concentrate diet.
• Cecal acetate levels were higher and propionate levels were lower at 1, 3, and 4 hours post-feeding in horses that received the sodium bicarbonate infusion compared to those only fed the concentrate diet.

Observations on Feeding Behavior

• Horses on the concentrate diet spent noticeably more time chewing wood and engaging in coprophagy (consumption of feces) than horses fed hay.
• Administering the sodium bicarbonate infusions seemed to reduce the time horses on the concentrate diet spent on these activities, but the differences were not statistically significant.
• There was a significant correlation between the amount of time spent chewing wood and the level of cecal propionate.