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Do Haynets Help Horses Lose Weight?By Kentucky Equine Research Staff · December 31, 2015

The equine obesity pandemic is real, with veterinarians and nutritionists issuing warnings to owners that there is no such thing as a fat, healthy horse.

“According to the latest American Horse Publications Equine Industry Survey, horse owners are primarily responsible for feeding their horses. Thus, the onus is on owners to identify overweight horses and then institute appropriate weight-loss measures,” advised Kathleen Crandell, Ph.D., a Kentucky Equine Research (KER) nutritionist.

Recognizing the importance of weight management in the equine population, researchers put eight Quarter Horses on a diet*. Horses started off with a body condition score (BCS) averaging about 7.3 and were fed 1% of their body weight in grass hay, either off the ground or from a haynet in two meals. The diet was designed using National Research Council** guidelines to achieve a loss of one BCS unit over a one-month period.

The researchers found that horses fed off the ground or by haynets both lost weight during the 28-day study period, an average of approximately 77 lb (35 kg). Nonetheless, they suggested that feeding horses a restricted diet using haynets was better than feeding off the ground for the following reasons:

  • Horses fed with haynets took longer to consume their meals. Ground-fed horses finished their meals in 120 minutes, whereas horses fed from haynets took 193 minutes. “Increasing the time horses spend foraging each day promotes gut health and hindgut fermentation, and has been shown to reduce stereotypical behaviors and the incidence of colic,” wrote the researchers.
  • Horses fed off the ground had higher cortisol levels. Cortisol is a reliable indicator of stress. This was thought to be due to anxiety associated with being able to see horses consuming forage from haynets once horses fed from the ground were finished their meals.

Based on these two findings, in addition to other data on hormone levels and body measurements, the study authors therefore concluded that haynets were useful when devising equine diets.

The researchers summarized, “The use of a slow-feed haynet coupled with a limit-fed diet appears to be an effective method for decreasing body weight and maintaining more homeostatic levels of postprandial metabolites and hormones when feeding overweight adult horses.”

*Glunk, E.C., M.R. Hathaway, A.M. Grev, et al. 2015. The effect of a limit-fed diet and slow-feed hay nets on morphometric measurements and postprandial metabolite and hormone patterns in adult horses. Journal of Animal Science 93(8):4144-4152.

**NRC. 2007. Nutrient Requirements of Horses, 6th Rev. Ed. National Academies Press. Washington, D.C.