Question
My Thoroughbred mare (5 years old; 15.3 hands [160 cm]; 1,000 lb [450 kg]) is very thin. I referenced the body condition score chart, and she’d be about a 3. She has 14-16 hours of access to pasture during the day, and she’s stalled at night. She’s fed 16 lb (7.25 kg) of a name-brand senior feed, 2 lb (0.9) of alfalfa pellets, and 40 lb (18 kg) of hay daily. With this diet, I thought she would gain weight quickly. She is in daily work of moderate intensity. She has been vet-checked several times and has been pronounced healthy though thin. I believe she has been stressed for two reasons: her transition from the rescue where I adopted her and an abscessed hoof. The hoof has healed, and she is sound. I think she could be dealing with gastric ulcers but shows no signs. Can you evaluate her diet?
Answer
How long have you had her? From your query, I assume the mare came into your care underweight, and I will provide feedback based on that supposition.
Mature horses in regular work have a voluntary dry matter intake of about 2-2.5% of body weight, such that a 1,000-lb (450-kg) horse will typically eat 20-25 lb (9-11 kg) of dry feed per day. Taking this into consideration, it is unlikely that the hay being fed is actually being consumed in sufficient amounts. As concentrate intake increases, the amount of hay eaten often decreases.
What type of hay is being fed? Offering a higher calorie, mixed hay (grass/alfalfa or clover) with fine stems and many leaves is recommended for hard keepers. Because of its palatability, horses often eat more alfalfa hay than grass hay of similar quality. Alfalfa cubes are a great option if you cannot source good-quality hay. Make sure she has fresh water available at all times. Offering soaked cubes is one way to increase water intake.
When feeding large amounts of concentrate feed, it is best to divide the total given in a day into at least three or four per day to try to keep meal size small and to reduce digestive upset, no more than 5 lb (2.2 kg) per feeding. The upper amount of total concentrate fed should be around 10-12 lb (4.5-5.5 kg) per day for a 1,000-lb (450-kg) horse in light or moderate work. In some cases, the exercise program may need to be decreased to allow the calories provided to be used for weight gain.
Horses can consume large volumes of fresh grass and often exceed intakes normally seen on hay and concentrate feed diets. Is good-quality grazing available? If so, then I would expect you to notice improvement in body weight as her time on pasture increases.
The current diet should be supplying sufficient calories to promote weight gain so other reasons for her lack of improvement could be dental or digestive issues such as gastric ulcers or parasite burdens. Some horses may not show clinical signs of gastric ulcers, so the only way to definitively rule out those are through endoscopy. If she is found to have ulcers, the veterinarian will likely prescribe a course of omeprazole, a drug designed to heal gastric ulcers. As the omeprazole therapy is winding down, I would transition her to a research-proven supplement that buffers the pH of the stomach to prevent new ulcers from forming.
KER Targeted Nutrition offers EquiShure, a time-released hindgut buffer that is beneficial in weight-gain situations, as it helps support the cecum and colon and is especially useful in cases where large amounts of concentrates are being fed.
Many Thoroughbreds have problems with hoof quality throughout their working lives. A high-quality hoof supplement that includes biotin and other important nutrients strengthens the hooves of many horses.
