Effects of feed deprivation on Standardbred horses fed a forage-only diet and a 50:50 forage-oats diet.

This research focuses on the effects of different diets on athletic horses before and after a period of food deprivation. It compares two diet types: one that includes only forage (FD), and the other a balanced mix of forage and oats (OD). It measures several factors like body weight, water intake, and certain metabolic markers in the horses’ plasma to determine the potential benefits and setbacks of a high-forage diet.

Methodology

• The research involved twelve adult Standardbred horses who were already undergoing training.
• Two types of meals, an all-forage diet and a 50:50 forage and oats diet, were fed to horses over two distinct experimental periods lasting three weeks each. These two periods followed a crossover design, meaning each horse was subjected to both diet types.
• At the end of each of these periods, the horses underwent a 12-hour fast.
• The researchers regularly weighed the horses and checked their water intake throughout the trial, including an hourly check during the 12-hour fasting period.
• Throughout the fasting period, the researchers analyzed the horses’ plasma for the presence of various substances, including total protein concentration, insulin, nonesterified fatty acids, urea, glucose, and acetate concentrations.

Results

• Researchers observed that the horses on the forage-only diet had higher body weights and consumed more water as compared to those on the mixed diet.
• Despite this, the weight loss experienced by the horses during the fasting period was greater when they were on the forage-only diet.
• Also, the total protein concentration in the horses’ plasma was lower on the forage-only diet before and during the last 8 hours of the fasting period.
• The level of insulin in the horses’ plasma was found to be lower in the horses on the forage diet than on the mixed diet at feeding time and for 5 hours during the fasting period.
• However, the levels of nonesterified fatty acids and urea (both metabolic byproducts) increased in all horses, regardless of the diet, while fasting.
• On the flip side, the glucose levels in the plasma were unaffected by either the diet or the feeding status.

Conclusions

• The study concludes that increasing the forage allowance for athletic horses could be used as an alternative to high grain diets.
• A slight increase in body weight on a forage-only diet was observed, but this increase diminished with prolonged periods of fasting.
• Lower plasma protein concentration in horses on a forage diet indicates a greater potential for unused internal fluid compartments to maintain plasma volume.