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Proper amounts of protein are critical for a horse’s diet

by Wyoming Livestock Roundup

Regardless of a horse’s responsibilities or the time of year, protein is vital to their diet, and the amount needed is largely based on their age and workload. 

“The right amount of high-quality protein will provide essential amino acids to support optimum horse health,” states Sarah McNaughton in a Farm Progress article published Oct. 3, 2023. “While protein is essential, too much consumed in the diet can cause kidney damage, so care must be taken to hit the proper amount.” 


supplementation options

On average, horses consume a variety of roughage and grains with varying levels of protein quality and quantity. 

Kentucky Equine Research (KER) Staff note soybean meal, linseed meal, corn gluten, canola meal and cottonseed meal are some of the most common protein supplements used in textured and pelleted feeds, and although they are all suitable components of horse feed, they deliver differences in quality. 

“Quality of protein is determined by amino acid composition,” KER says. “A single amino acid – lysine – is of particular importance to horse owners.” 

“High-quality protein feedstuffs are those which contain high amounts and proportions of essential amino acids,” agrees Iowa State University Extension and Outreach. “The best indicators listed on commercial feed tags are the essential amino acids lysine, methionine and throenine, although lysine is the only one routinely listed.” 

Iowa State further notes high-quality protein feedstuff includes legumes, young grass pastures, canola meal, linseed meal and soybean meal, which is rated the highest quality because it has a superior amino acid profile. 

On the other hand, cereal grains and grain byproducts have moderate- to low-quality protein content. 

Specific protein


Regardless of how protein is supplemented in the diet, a horse’s protein requirement will vary depending on their age and workload. 

McNaughton points out fully-mature horses at maintenance require the lowest protein requirement, needing only 1.4 pounds per day, which can be achieved through grazing or feeding on grass hay, as long as quality is average or above average. 

Working and performance horses with a heavier workload should consume more protein – up to 1.9 pounds per day, according to McNaughton. 

“For horses involved in regular athletic activity, protein works alongside starch, fat and fiber to fuel working animals,” she explains. “Excess protein consumed can be turned into a source of energy as the amino acids present in excess protein are broken down by the liver.” 

Younger horses also require greater amounts of protein in their diet.  

McNaughton notes a 550-pound weanling should receive about 1.5 pounds of protein per day, while an 850-pound yearling should consume 1.75 pounds per day. 

“Up to two pounds of protein may be needed daily for animals in training programs,” she adds. 

Additionally, during the last 90 days of gestation, broodmares will require around two extra pounds of protein daily in order to meet their own requirements and build fetal tissue. 

“Lactating mares have the highest protein requirement of all, as large amounts of protein leave through mare’s milk,” McNaughton explains. “For horses that do not receive enough protein, owners can expect to see decreases in milk production and lowered foal growth. Three to 3.4 pounds of protein is needed each day for this class.” 

Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to

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