Effects of cereal grain supplementation on apparent digestibility of nutrients and concentrations of fermentation end-products in the feces and serum of horses consuming alfalfa cubes.

The study investigates the impact of grain supplementation on the digestion and metabolic processes of horses consuming alfalfa cubes. The grains under study included barley, corn, naked oats, and oats. The key conclusion is that these grains can be safely incorporated into the horses’ diet without negatively affecting the digestion or overall health of the animals.

Research Design and Methodology

• The experimental design was a completely randomized design involving twenty geldings, divided into five groups. One group, the control, consumed alfalfa cubes without any grain supplementation, while the other four were each supplemented with a different type of rolled cereal grain to provide a targeted intake of total nonstructural carbohydrates (TNC).
• The horses were fed two equal meals per day (at 0600 and 1800) and adapted to the diet over a six-week period.
• However, due to cases of acute laminitis with three of the horses and several incidents of gas colic, the TNC level had to be reduced to 0.2% of the horse’s body weight to maintain their health during the adaptation and sample collection periods. This highlights the necessity of ensuring the health and safety of experimental subjects during the research process.

Results and Findings

• The results indicated that grain intake varied depending on the different TNC concentrations in each type of grain.
• The apparent digestibility of key nutrients, including DM, OM, CP, NDF, ADF, and cellulose, was not significantly affected by grain supplementation.
• Regardless of the type of grain used for supplementation, the addition of grain increased the apparent digestibility of TNC and resulted in a decrease in fecal pH.
• The study also found differences in the fecal concentrations of total Volatile Fatty Acids (VFA), lactate, and NH3 N among the various diets. For example, barley and naked oats diets had the highest total VFA concentration while lactate concentration was highest in the barley diet. Similarly, naked oats diets resulted in the highest fecal concentration of NH3 N.
• Serum concentrations of lactate were found to be higher in the control group than in the grain diets, while serum NH3 N concentrations were higher in the diets with the various grains than in the control diet. Urea N concentrations were higher in the serum of horses fed the control, barley, and naked oats diets than in those fed the corn or oats diets.

Conclusion

• The study concludes that supplementation of horse diets consisting of alfalfa cubes with any of the four grains (barley, corn, naked oats, or oats) does not have any significant negative effects on nutrient digestion or overall health, as long as it does not exceed 0.2% of the horse’s body weight as TNC.
• This finding provides a valuable contribution to the understanding of equine nutrition, particularly in the context of optimizing diet composition for horses.