Achieving weight gain in skinny horses is often a matter of reworking the diet to maximise energy consumption. Common sense approaches to weight gain involve bumping up forage quality and quantity, adding a suitable feed, or supplementing with a high-calorie additive.
Many horses are able to gain weight with unlimited access to high quality forage including grazing on high-quality pasture. This is especially true in the spring and autumn when a flush of fresh grass is available. However, not all horses can handle full-out access to pasture, so consult a veterinarian if a horse has a history of metabolic disease or laminitis.
In terms of hay, consider best-quality grass or lucerne hay for horses in need of weight. Top-quality hay will cost more than mid-quality because of its greater energy content. Avoid any hay that is musty, dusty, or mouldy. Aside from good-quality pasture and hay, alternative forage sources often have a place in the diets of skinny horses, primarily because they are consistent in quality and palatable to most horses. Alternative forages include chaff, hay cubes, beet pulp (Speedi-Beet) and soy hulls.
Horses require substantial fuel for growth, performance, and reproduction, as well as to power everyday body processes. As grazing animals, forages are the primary energy sources for healthy horses.
A healthy horse with a normal metabolic rate that requires neither weight gain nor weight loss would likely maintain condition on 1.5-2% of its body weight in forage per day. For a 550kg horse, this would equate to 8-10kg of forage (dry matter) daily.
Horses that require weight gain can be offered more forage than this, up to 3% of body weight. Maximal forage intake is 3-3.5% of body weight per day for most horses, though lactating mares and other horses with extreme energy needs might consume 5% of body weight daily.
When feeding hay or alternative forage sources, astute management can help determine how much should be fed. When feeding for weight gain, some horse owners will offer free-choice forage, adjusting the amount based on whether the horse cleans up what is offered or leaves a portion.
Also keep in mind horses on all-forage diets require vitamin and mineral supplementation for optimal health.
Feeds and grains.
Balancing out the forage in a horse’s diet usually comes down to adding a feed or concentrate that is fortified with vitamins, minerals and quality protein, with exact amounts dependent on forage type and the individual horse.
For mature horses in need of weight gain, it is often wise to choose a feed that contains a variety of energy sources (calories), meaning the feed includes starch (grains such as oats, corn and barley), fat (vegetable oil, stabilised rice bran), and fermentable fibre (beet pulp, soy hulls, lucerne meal). Feeds intended for performance horses often feature these blends, as do feeds manufactured for breeding and senior horses.
Typically, fortified concentrates are formulated to be fed at a level of intake between 2-4kg per day. A common mistake made with concentrates is to feed less than the minimum recommended level, a practice that could lead to suboptimal vitamin and mineral nutrition. Therefore, it is important to follow the manufacturer’s recommendation in figuring how much to feed.
High-Calorie Feeds and Supplements.
Energy-dense supplements can be added to the diet to increase calorie consumption including fats and oils. Vegetable oils including canola, soy bean, linseed and rice bran oils are good calories sources for horses. Fish oil provides the highest quantity of omega-3s, and the numerous health benefits associated with them, but it is generally not used as a source of supplemental calories.
Another common high-fat supplement beneficial for skinny horses is stabilised rice bran (EquiJewel). Highly digestible and palatable, rice bran contains about 20% fat. Like vegetable oil, it is usually top-dressed onto concentrate meals. Typical serving size for rice bran is 500g-1kg per day, divided among feedings, though more can be fed if necessary.
Developing and then fine-tuning a diet for an underweight horse requires an understanding of how best to deliver energy.