Impact of barley form on equine total tract fibre digestibility and colonic microbiota.

The research article studies the effect of different forms of barley on the digestion of dietary fiber in horses. The study found that processed forms of barley had a greater digestibility than whole forms and did not adversely affect the fiber degradation in the horse’s gut.

Methodology

• The research was conducted with four mature horses, each fitted with a right ventral colon-fistula to facilitate observation of the digestive process.
• The horses were fed a diet of meadow hay and concentrate (in a 62:38 ratio on a dry-matter basis) at 1.7% of their body weight. 80% of the concentrate was made of barley, provided either as whole grain or processed in one of three forms: 2.5 mm ground, pelleted, or steam-flaked.
• In each period, total tract apparent digestibilities of dry matter (DM), neutral detergent fibre (NDF), and acid detergent fibre (ADF) were determined over three consecutive days. This was achieved by collecting total fecal matter.
• pH levels, volatile fatty acids (VFA) concentrations, and functional bacteria counts were also evaluated in the colonic content, four hours after the horses were fed in the morning.

Findings

• Barley form significantly influenced total tract apparent digestibility of dry matter and dietary fibre.
• Diets composed of thermo-mechanically treated barley forms (pelleted or steam-flaked) resulted in a higher total apparent digestibility of NDF compared to diets consisting of ground barley.
• Similarly, diets composed of thermo-mechanically treated barley forms resulted in greater total apparent digestibility of ADF compared to diet with whole or ground barley forms.
• No significant difference was noted in the colonic pH, concentrations of VFA and functional bacteria.
• Despite a high supply of starch in the morning meal, the concentration of functional bacteria such as total anaerobic, cellulolytic, amylolytic bacteria and lactic acid-utilising bacteria remained within beneficial ranges.

Conclusion

• The study concludes that providing horses with pelleted or steam-flaked barley instead of ground barley forms can lessen the negative impact of starch on fibre digestibility in horses, specifically when they are given a high level of starch in the morning meal.
• The fibre-to-starch ratio fed in this experiment did not cause any digestive upset, indicating the balance was appropriate for the horses’ digestive health.