Long Ear Nutrition: Donkey Edition

Donkeys are becoming more and more common as both companions and working animals on farms. Donkeys are members of the equidae family and are often treated like horses, but are very different in their looks, behaviors, mannerisms, and especially nutritional needs.

Evaluating Body Condition

Donkeys evolved eating very fibrous forages that were lower in calories compared to the commonly available forages in the United States. The nutrient-dense forages available today have contributed to an obesity problem in donkeys.  Donkeys should have their body condition monitored regularly as part of a program to avoid obesity. The Henneke Body Condition Scoring System is a scale (1–9) used to evaluate fat deposits on the neck, withers, shoulder, down the back, ribs, and around the tailhead on the horse. This scoring system should not be used for donkeys due to differences in fat deposits and conformation. The donkey body condition scale ranges from 1–5, with 1 being emaciated, 3 being ideal, and 5 being extremely obese. Evaluating donkey body condition is done by feeling the amount of fat and muscle coverage along the neck and shoulders, withers, ribs and belly, back and loins, and hindquarters. Monitoring body condition regularly is a good way to identify weight gain or loss before it becomes extreme and creates health issues.

Nutritional Needs

Donkeys evolved from the African Wild Donkey in a hot, semi-arid climate with access to low-energy, highly fibrous forages. Due to this, the donkey is both a browser and grazer, meaning they will consume grasses, trees, and woody shrubs. Although donkeys can utilize poorer quality forages, they are highly selective and will seek out the highly digestible forages first. Similar to the horse, the donkey is a hindgut fermenter, and the digestive system was designed to have multiple small meals frequently throughout the day. However, it has been found that the donkey's ability to utilize highly fibrous forages is more similar to a goat than a horse.

Digestible Energy

Digestible energy (DE) is the amount of energy in the feed minus the amount lost in feces. Compared to the horse, the donkey only requires around 75% of the DE that a horse of the same size needs. This is likely due to the higher efficiency of the hindgut of the donkey compared to the horse. Research has shown that food moves through the donkey's digestive tract slower than it would in the horse’s digestive tract. This allows the microbes in the hindgut more time for fermentation, which will extract nutrients and produce more volatile fatty acids, which are later used for energy.

Protein

Proteins are made of amino acid building blocks that are utilized in most functions in the body. The donkey is much better at utilizing dietary protein than the horse and requires less in the diet. The average horse requires between 8–12% protein in the diet, while the average donkey requires 3.8–7.4% in the diet.

Carbohydrates

Carbohydrates are classified into two main categories: structural and nonstructural. Structural carbohydrates (cellulose, hemicellulose, or lignin; aka plant fiber) are the portions of the cell wall that cannot be broken down in the small intestine and must be fermented in the hindgut to provide any type of nutrient to the donkey. Nonstructural carbohydrates (NSC) such as simple sugars and starch are broken down in the small intestine. The traditional diet for the donkey is high in structural carbohydrates (fiber) and lower in NSC. High levels of NSC in the diet can lead to serious health problems, like laminitis, metabolic conditions, and obesity.

Fat

There is minimal fat in the traditional diet for a donkey. Fat is the most calorically dense nutrient and should be limited in the diet for most donkeys. High fat supplements should be avoided in the diet and should only be added if weight is needed, and it is recommended by a nutritionist or veterinarian.

Water

Water is a very important nutrient in the donkey’s diet. The donkey can regulate water in the body better than the horse and can go longer without access to water. However, fresh, clean water should be available at all times.

Feeding Recommendations

Forage

The most suitable forage for a donkey is straw. Straw is the stem left over from cereal grains after the seed head is removed, like barley, wheat, and oats. Straw tends to be higher in fiber and lower in NSC, which is ideal for a donkey. If straw is not available, feed a mature grass hay that is lower in digestible energy, protein, and NSC and higher in neutral detergent fiber (NDF; ideal for a donkey would be around 70% as-fed). This type of hay tends to be lower in protein and NSC, which is suitable for donkeys; however, it is important to get a hay analysis to be certain of the levels of protein and NSC, as well as other nutrients. Legume hay, such as alfalfa and clover, should be avoided because it is high in protein and digestible energy and can lead to obesity and weight-related conditions. Pasture grasses should be limited or avoided because of the varying nutritional values, especially NSC. A grazing muzzle can be used to reduce intake, but still allows the donkey to use the pasture for exercise and social interaction. Reach out to your local extension agent to help identify trees and woody shrubs in the pasture because some can be harmful, like cherry trees or black walnut. Donkeys are predisposed to conditions like obesity, equine metabolic syndrome, and laminitis. Monitoring the amount of NSC and calories can help prevent some of these conditions.

Grains/Concentrates/Supplements

Donkeys have vitamin and mineral requirements that are typically not met by a forage-only diet. A loose vitamin and mineral supplement can be added to provide these essential nutrients without added calories. A salt block can also be provided, but it is difficult to regulate intake because some animals will not lick the block. Another option is a low-NSC ration balancer fed at the appropriate amount (directions on bag). Whole grains, such as oats, are not balanced with vitamins and minerals and are higher in NSC, making them unsuitable for donkeys. Low-NSC concentrates can be used for donkeys that require extra calories to maintain their weight, but sweet feeds and high-NSC concentrates should be avoided. If a donkey has problems with chewing or cannot digest long-stem forage, pelleted or cubed forage can be used in combination with a ration balancer or low-NSC concentrate to provide the necessary nutrients and still provide some type of forage fiber. The last option is to transition to a diet comprised of a complete feed, which is a concentrate that provides the total ration in pelleted or extruded form. A nutritionist can help balance these diets. For all types of ration balancers, commercial concentrates, and complete feeds, the feeding rates on the bag should be followed. Always monitor your donkey for changes in weight and BCS to decide if their feeding plan needs to be adjusted.

Conclusion

There are big differences in the nutrient requirements of the horse versus the donkey. Overall, the donkey requires less nutrients compared to the horse and is typically fed about 25% less than a horse of the same size. Reach out to a nutritionist or a veterinarian for more help in feeding donkeys.

Resources

All About Donkeys, The Donkey Sanctuary

Donkey's Unique Nutritional Needs, Cornell Extension, Ulster County

Donkey Body Score Chart