They might be small in size, but weanlings have substantial nutrient requirements to effectively fuel growth and development. Unfortunately, their bodies can make getting these nutrients challenging. They’re unable to fully utilize nutrients in forage until the incomplete microbial colonies in their hindguts develop. In the past, this concern led many to feed weanlings extra concentrates, but recent studies have shown that high-carbohydrate diets can put young horses at risk for developmental orthopedic diseases.
So can weanlings get by on diets high in forage and low in concentrates? Researchers tested three diets to find out.
A team from Michigan State University (MSU), in East Lansing, fed 24 Quarter Horse and Arabian weanlings three diets at 3.5% body weight:
- A high-concentrate diet (High Con), with a 70:30 concentrate-to-roughage ratio;
- An equal diet, with a 50:50 ratio; and
- A low-concentrate diet (Low Con), with a 30:70 concentrate-to-roughage ratio.
“The grain and hay were combined into a pellet so that we were guaranteed horses were consuming the required ratio of hay to concentrate,” said Brian Nielsen, PhD, PAS, Dipl. ACAN, a professor of equine exercise physiology at MSU.
Key study findings included:
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- Weanlings’ average body weight remained the same between treatment groups, and they consumed the same amount of feed regardless of diet;
- Horses eating the High Con diet had better crude protein digestibility than those eating the Low Con or equal diet;
- Low Con horses tended to digest more neutral detergent fiber (NDF, the structural parts of hay) than the other groups; the team said this suggests that weanlings fed high-fiber diets could be more efficient at digesting forage than those consuming diets higher in concentrates; and
- Regardless of the concentrate to roughage ratio, the weanlings were able to get enough nutrients out of their diets to meet or exceed the requirements in the National Research Council’s Nutrients Requirements of Horses.