Manage non-structural carbohydrates in equine forages

 By: John Goeser, PhD, PAS & Dipl. ACAN, Rock River Laboratory Animal Nutrition, Research, and Innovation Director and Amber Krotky, Research & Development Manager at MARS horsecare us inc

Equine nutrition has historically centered on providing a high quality, grass hay along with a commercially prepared ration balancer or compound feed. However, ‘quality’ hay is loosely defined, as what may be considered ‘high-quality’ for one animal may not necessarily be optimal quality for another animal. Generally speaking, protein, fiber, non-structural carbohydrates (NSC), and minerals are all measured components used to assess hay quality. But, NSC has gained more attention than the other components over the past few years as horse owners work to dial in exactly how high or low this component needs to be for their horses’ needs.

What makes the quality definition for hay so important is the role of forage as a critical component to maintaining gut health in the horse. Ideally horses should consume 1.5 to 2.0 percent of their body weight in forage per day (never less than 1.0 percent) (A. Krotky, personal communication). Hay intended for consumption by horses should contain protein levels that meet the animal’s nutrient requirements based on their activity level. For instance, a performance horse will likely require greater protein content in the forage portion of its diet. The structural fiber and mineral content of the hay can help meet nutritional needs, and the NSC content of the forage can be considered when horses encounter metabolic challenges.

Sugar, fructans, and starch comprise NSC (Watts, 2009), and each of these nutrients are readily and rapidly digestible within the monogastric digestive system of the horse, providing useable energy after consumption. Working or performance horses may require substantial NSC to meet energy demands, whereas mature, less active horses require little to no additional NSC (Pagan, KY Equine Research). This difference in NSC needs within this species has driven additional research and review of NSC in equine hay.

 For dairy and beef cattle, NSC are valuable in providing these high-performing animals with energy for growth and production. For idle or low-activity horses, a high NSC level in hay has resulted in diagnoses of, or related to, carbohydrate intolerance (Watts, 2009). Clinical illnesses such as obesity, laminitis, and insulin resistance seem increasingly prevalent in the equine species as this intolerance grows. Mature hays, or forages that have spent greater time growing before being cut to dry for hay, generally have lesser NSC content because the sugar and starches are diluted by greater fiber content. However, horse owners looking to grow or purchase hay with lower NSC content may run into some difficulty as even some mature hays contain substantial NSC.

Here are a few items to consider to when choosing and feeding hay for the optimal health of your horse:

1. Understand your horses’ activity level and metabolic issues while paying special attention to weight loss or gain.

• Equine nutrient requirements for energy will vary depending on:
  • Environmental conditions such as cold or hot weather:  more energy is spent maintaining normal body temperature
  • Growth stage: young and growing horses need more energy and protein
  • Activity level: active versus less active can drive energy needs
  • Breeding status
• Work with your nutritionist and veterinarian to assess body condition score (BCS). Ideally a BCS of 5 on a scale of 1 through 9 is ideal for the average horse.

 2. Work with your nutritionist or veterinarian to ensure adequate vitamin and mineral supplements are consumed as necessary.

 3. Assess hay quality through a nutrient analysis on an interval that makes sense for your horse(s) or farm:

• Sample hay monthly, quarterly or annually depending on hay variability if purchasing small quantities at a time.

 4. Take a scissor clip sample of pasture grass and send to a certified laboratory to assess the forage’s quality during the growing year:

• Hay and pasture quality will vary from year to year, particularly in NSC, and depending on pasture maturity.
• Do not assume mature hay or pasture grass will produce less NSC.

Ultimately, consult with your nutritionist or veterinarian to better understand your horses’ nutritional needs based on their activity level or metabolic condition, and then set benchmarks to review as seasons change. Assessing your horses’ hay nutritive value when you switch between crops of hay or pastures is also a good practice to maintain for any size equine operation. All horse owners should pay close attention to forage sources’ effects on their horses throughout the year, while monitoring the hay NSC value as it relates to your horses’ energy needs. Preventing common NSC-intolerance driven illnesses by measuring and monitoring is always easier than treatment after a health challenge has developed.

*Acknowledgements: We would like to express appreciation and acknowledge Amber Krotky’s review and contribution to this article.

References

Pagan, J.D. Carbohydrates in Equine Nutrition. Kentucky Equine Research, Versaille, KY.

Watts, K.A. 2009. Carbohydrates in forage: what is a safe grass? pgs 29-42. Advances in Equine Nutrition – Vol. IV., Ed. J.D. Pagan. Kentucky Equine Research, Versaille, KY, USA. Nottingham University Press.