Equine pre-caecal and total tract digestibility of individual carbohydrate fractions and their effect on caecal pH response.

The research under discussion investigates how different types of carbohydrates in horse feed can affect the digestion process and caecal pH in horses. The study particularly focused on the impact of soluble fiber on fermentation and overall digestibility.

Research Methodology

• The study adopted a 4×4 Latin Square design which involved a schedule of 17 days for getting used to a new diet, followed by 8 days of sample collection.
• The research was conducted on four horses equipped with permanent caecal tubes and collection harnesses, utilized to obtain accurate and consistent data.
• The different diets tested consisted purely of timothy hay, hay with molassed sugar beet pulp and oats, hay with beet pulp and barley, and hay with loose chaff-based concentrate.
• A mobile nylon bag technique was employed to determine pre-caecal loss (PCL) of the individual feed components.
• A pH meter with a logger was inserted to record caecal pH at 1-minute intervals for 8 hours, providing critical insights into the horse’s digestive health.

Analytical Components and Findings

• In the analysis, fiber was assessed in terms of various components: dietary fibre (DF), non-starch polysaccharides, soluble non-cellulosic polysaccharides (S-NCP), insoluble non-cellulosic polysaccharide (I-NCP), and neutral detergent fibre.
• The findings from the research demonstrated that the digestibility (ATTD) of the S-NCP fraction was above 0.8. This figure is significant as this value was 60% higher than the ATTD for the I-NCP fraction, showing that soluble fibre is more digestible than insoluble fibre for horses.
• The PCL of starch was higher for oats (0.98) than barley (0.75), illustrating a difference in the digestibility of starch from these two grains.
• The study also revealed that unprocessed barley enough to significantly reduce caecal pH, thus negatively impacting the overall digestibility of fiber in the diet.

Conclusion

• The research successfully demonstrated the digestibility of individual fiber components in horse feed and how they impact the digestive health of horses.
• Moreover, the study revealed that soluble non-cellulosic polysaccharides are more digestible than their insoluble counterparts and that a single meal of unprocessed barley could significantly reduce the digestibility of the fiber in the horse’s diet due to its effect on decreasing caecal pH.