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In May 2024, a diet evaluation was requested for Phix, an eleven-month-old appaloosa gelding in Nova Scotia, Canada. At the time of the submission, he weighed approximately 550 lb (250 kg). Phix was reported to be healthy but slightly underweight.
The horse owner’s primary goal was to encourage weight gain to achieve a healthy body condition score.
Presentation Prior to Diet Intervention
Phix was described as slightly underweight in his submission, a description which the owner and the horse’s veterinarian agreed on.
He also had other environmental changes worth considering. At the time of submission, he had been recently castrated and was being hand walked often to minimize swelling and encourage drainage while he recovered from this routine surgery. .
The following photos were provided of the gelding from May 2024:
Horse History
At the time of submission, Phix measured 14.5 hh tall, and was estimated to have a body condition score of 3.75 on the 9-point Henneke scale.
He was provided free choice access to hay and pasture. In addition, he was fed sixteen cups of Purina Evolution Juvenile spread over three meals throughout the day.
Forage analyses were not available, so nutrient intake estimates were made using average quality grass hay and pasture for his geographic region.
Feeding Growing Horses
Growing horses typically reach around 60% of their mature body weight by 11 months old. [1] While their growth rate is declining at this stage, they still require an energy- and protein-dense diet to support healthy growth and development.
In addition to meeting protein and energy requirements, growing horses also require sufficient mineral and vitamin intake from the diet.
The ideal body condition score for a growing horse is 4 to 5 on the Henneke Scale. This can be achieved by providing high-quality forage and protein sources, as well as vitamin and mineral supplementation.
Complete feeds designed for growing horses are commonly used to achieve these goals, although energy and protein sources such as alfalfa, soybean meal, and oil can also be fed alongside a complete vitamin and mineral supplement to meet growing horses’ dietary needs.
Once basic nutrient requirements are met, there are additional aspects to consider when balancing the diet for a growing horse. Avoiding excessive energy, sugar, and starch intakes can help prevent issues with normal musculoskeletal development and growth.
Developmental orthopedic diseases (DODs) are a group of conditions related to abnormal cartilage, bone, or soft tissue development. Genetics, growth rate, and nutrition can impact the likelihood of DOD development. While each of these factors alone may not lead to the development of DODs on their own, it is likely that a combination of factors leads to disease development.
For example, some horses may tolerate a relatively high energy intake without developing DODs, while those with a genetic predisposition to DODs may not fare as well.
Additionally, while some horses may tolerate a high-calorie intake when the calories come from protein or fat, an excess intake of sugar and starch (hydrolyzable carbohydrates or HC) can have a more negative impact.
Feeding excess energy may contribute to rapid growth that predisposes foals to DODs. Several studies have shown an association between excess energy intake and the presence of osteochondrosis dissecans lesions, conformation abnormalities, and disturbances in growth plates. [2]
In addition, high sugar and starch intakes can affect hormonal balance, which can in turn affect the development of bone and cartilage. Thus, high sugar and starch intakes may contribute to hormonal alterations that increase the risk of DODs. [3]
In Phix’s case, there were no indications of developmental orthopedic disease at the time of dietary intervention. However, when reformulating the diet to encourage weight gain, it was important to provide a moderate energy intake while limiting sugar and starch consumption.
Feeding Underweight Horses
Weight loss can occur in horses due to a number of health and dietary factors, including:
- Lack of forage availability
- Low quality forage
- Digestive disorders
- Other underlying medical conditions
Horses are continuous grazers, so increasing their forage quantity or quality is often the easiest and most affordable way to encourage weight gain. In cases where forage intake is already maximized and quality is sufficient, additional calories can be added in the form of energy-dense feeds.
Diets with excessive sugar and starch should be avoided, as these diets can cause digestive issues that further hinder weight gain. [4][5][6]
For most horses, it’s recommended to keep the HC content under 12% of the diet on a dry matter basis. In some cases, feeding higher HC intake may be appropriate, such as for horses that need more energy to fuel performance. Conversely, some horses benefit from having HC further restricted to 10% or less of the diet to support metabolic health.
As an alternative to sugar and starch, calories from fiber- and fat-rich sources are recommended to increase calorie intake. Fiber-based feeds such as beet pulp and alfalfa, or fat sources like oils or flax provide highly digestible fiber and fat to increase calorie intake.
When adjusting the calorie intake of growing horses, ensure that protein requirements are still met. If concentrate feeds are reduced to control HC levels, alfalfa can be added to maintain protein intake and supply calories from highly digestible fiber.
In the present case, Phix had been evaluated thoroughly by a veterinarian with no indication that digestive or other health issues were contributing to his condition. However, the HC content of his diet was slightly elevated.
Initial Diet
At the time of the nutrition consultation, Phix’s daily ration consisted of:
- Free choice grass hay and pasture
- 16 cups per day of Purina Evolution Juvenile
Overall, the diet was meeting his protein, vitamin, and mineral requirements, and provided approximately 98% of his daily calorie requirement. However, the HC (sugar and starch) content of the diet was slightly elevated at 13.3% on a dry matter basis.
Intervention
As part of the consultation, an updated diet plan was proposed to address Phix’s weight and the balance of his diet.
Table 1. Summary of Diet Intervention
| Issue | Nutrition Goal | Intervention | Notes |
|---|---|---|---|
| Slightly Underweight | Increase calorie intake |
|
|
| Slightly High HC Intake | Reduce HC Intake |
|
|
Complete feeds are a good source of energy, protein, vitamins, and minerals, but they need to be fed at the recommended daily rate to fulfill all of a horse’s vitamin and mineral requirements.
Feeding a reduced rate of complete feed to avoid excess HC intake may be advisable, but it’s important that the diet is properly balanced to meet vitamin and mineral requirements.
In such situations, replacing some of the commercial grain with calories from fat and fiber, and adding a vitamin and mineral supplement can meet horses’ requirements without feeding excessive sugar and starch.
To replace calories from grain and increase energy intake, alfalfa and W-3 Oil were added to the diet. In addition to being a good source of calories and supplemental vitamin E, W-3 Oil contains added DHA and omega-3 fatty acid. DHA can have an anti-inflammatory effect on joints and may support healthy cognitive development. [7][8][9]
To balance the diet, Mad Barn’s Omneity® Pellets were added as a concentrated source of vitamins and minerals. Omneity is formulated with 100% organic trace minerals, complete B-vitamin supplementation and 20 mg of biotin (per serving) to support hoof health.
Meeting a horse’s sodium requirement is also an important factor to encourage proper hydration. Table salt can be dressed on horses’ meals or hay to meet their sodium requirement.
Balancing the Diet
The primary focus of dietary intervention was Phix’s body condition. Given that his protein, vitamin, and mineral requirements were met, it was important to rebalance the diet to reduce his HC intake and increase his calorie intake while still supplying adequate protein, vitamins, and minerals.
Feeding Omneity® Pellets and W-3 Oil alongside alfalfa and a reduced rate of complete feed helped to ensure the that his vitamin and mineral requirements were still met while addressing concerns related to the energy content of his diet.
Updated Diet
After the consultation, the owner made the recommended adjustments. Phix’s updated daily diet consisted of:
- Free Choice Grass Hay and Pasture
- 1.5 kg (4 lb) alfalfa
- 1 kg (2.2 lb) Purina Evolution Juvenile
- 200 mL (7 oz) W-3 Oil
- 1/2 scoop (50 grams) of Omneity® Pellets
- 2 teaspoons of loose salt
Outcome
Overall, the dietary adjustments led to a significant improvement in body condition. The owner noted that she began seeing improvements after just a couple of weeks.
The following photo shows Phix’s body condition after two months on the recommended diet:
Phix (center) AfterDiet Intervention
Discussion
Growing horses have high energy demands to fuel healthy growth and development, and it is not uncommon to see seasonal changes in body condition and growth rate when energy-dense forage sources like pasture are not available.
Given that Phix was also recently gelded, adding another stressor, it is not surprising that he was having difficulty maintaining weight in the beginning of spring when the grass was just beginning to re-emerge.
Since the diet was relatively well-balanced at the time of evaluation, increasing his caloric intake while meeting protein, vitamin, and mineral requirements was a priority for the updated feeding program. Due to the potential impact of elevated HC intakes on digestive health, reducing the HC content of the diet was also important.
The addition of Omneity® and salt helped to meet his nutrient needs and support healthy growth and development. Increasing his calorie intake and reducing his HC intake helped to encourage weight gain and resulted in achieving a healthy body condition of approximately 5 on the Henneke scale within a couple of months.
References
- National Research Council. Nutrient Requirements of Horses: Sixth Revised Edition. The National Academies Press, Washington, DC.
- Julliand, V. et al., Eds. Nutrition of the Performance Horse: Which System in Europe for Evaluating the Nutritional Requirements?: Proceedings of the First European Workshop on Equine Nutrition; Dijon, France, 17 – 18 January, 2002. Wageningen Acad. Publ, Wageningen. 2004.
- Geor, R. J., Ed. Equine Applied and Clinical Nutrition: Health, Welfare and Performance. Saunders Elsevier, Oxford. 2013.
- Raspa, F. et al. A High-Starch vs. High-Fibre Diet: Effects on the Gut Environment of the Different Intestinal Compartments of the Horse Digestive Tract. BMC Veterinary Research. 2022. doi: 10.1186/s12917-022-03289-2. View Summary
- Colombino, E. et al. Gut Health of Horses: Effects of High Fibre vs High Starch Diet on Histological and Morphometrical Parameters. BMC Veterinary Research. 2022. doi: 10.1186/s12917-022-03433-y. View Summary
- Raspa, F. et al. Microbiota Characterization throughout the Digestive Tract of Horses Fed a High-Fiber vs. a High-Starch Diet. Frontiers in Veterinary Science. 2024. doi: 10.3389/fvets.2024.1386135. View Summary
- Manhart, D. R. et al. Markers of Inflammation in Arthritic Horses Fed Omega-3 Fatty Acids. The Professional Animal Scientist. 2009. doi: 10.15232/S1080-7446(15)30702-6.
- Zicker, S. C. et al. Evaluation of Cognitive Learning, Memory, Psychomotor, Immunologic, and Retinal Functions in Healthy Puppies Fed Foods Fortified with Docosahexaenoic Acid–Rich Fish Oil from 8 to 52 Weeks of Age. Journal of the American Veterinary Medical Association. 2012. doi: 10.2460/javma.241.5.583.
- Nogradi, N. et al. Omega‐3 Fatty Acid Supplementation Provides an Additional Benefit to a Low‐Dust Diet in the Management of Horses with Chronic Lower Airway Inflammatory Disease. Journal of Veterinary Internal Medicine. 2015. doi: 10.1111/jvim.12488. View Summary
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