In vitro fermentation of feces from normal and chronically diarrheal horses.

The research article presents a study conducted on fecal samples from healthy horses and those suffering from chronic diarrhea. The aim was to understand the differences in fermentation in the two groups, both with and without the addition of an essential amino acid mixture. It was found that adding the amino acid mixture didn’t significantly affect fermentation in the healthy horses. However, for the horses with diarrhea, there were notable changes in gas and volatile fatty acids production.

Essential Amino Acid and Fermentation

• The article starts by explaining the procedure of the study. Fecal samples were taken from both healthy horses and those suffering from chronic diarrhea. They were subjected to an in vitro fermentation procedure using a closed system. During this process, an essential amino acid (EAA) mixture was added to some samples, while others were examined without it.
• In the case of healthy horses, the addition of the EAA mixture did not significantly alter the results of the fermentation process. This suggests that the healthy horses’ digestive systems functioned normally, regardless of the presence or absence of the EAA mixture.

Fermentation Differences in Diarrheal Horses

• Contrastingly, in horses suffering from chronic diarrhea, the addition of the EAA mixture showed a significant increase (P<0.01) in gas and total volatile fatty acids production. This shift occurred irrespective of whether the EAA was present or not, suggesting that unhealthy horses' digestion is altered in a way that it produces more gas and volatile fatty acids.
• Furthermore, alpha-amino nitrogen was utilized in significantly greater amounts (P<0.01) only if the EAA mixture was present. This suggests that the horses' digestive system responds differently in the presence of additional essential amino acids, particularly when they are unhealthy.

Post-Treatment Evaluation

• The fermentations were repeated after treating some of the diarrheal horses with oral iodochlorhydroxyquin for a week, which resulted in a positive clinical response. However, no significant difference was observed between pre- and post-treatment fermentations, with the exception of decreased butyrate production – a type of short-chain fatty acid.
• The lack of substantial change suggests that the treatment did not dramatically alter the digestive system’s fermentation process. However, the decrease in butyrate production may indicate a potential aspect of the pathology of chronic diarrhea in horses.

Interpretation and Hypothesis

• The results of the research support the hypothesis that chronic equine diarrhea is primarily a colonic disease. This conclusion is based on the premise that fermentation changes occur in the colonic region of the digestive system, where water is reabsorbed into the body.
• Moreover, the findings suggest that colonic maldigestion may be partly responsible for the excess fecal water observed in horses suffering from chronic diarrhea. If the colon is not digesting and absorbing substances properly, it could result in increased water content in the feces, thereby causing a symptom of chronic diarrhea.