In the last blog, we discussed the minerals required by a horse in large volumes such as calcium, phosphorus, magnesium, and potassium. We also covered the importance of incorporating the trace minerals copper, zinc, and manganese into the diet and how organic forms of these minerals may improve absorption rates and utilization. Finally, we touched on vitamins A, D, and E. This month we will turn our focus to less commonly used ingredients that really make a feed unique and beneficial to a horse.

Since we left off on the last blog with the fat soluble vitamins A, D, and E it seems fitting that we should start this month with water-soluble vitamins. Let’s begin with vitamin C; many of us are familiar with vitamin C as we often reach for it at the first sign of a cold. That is because vitamin C is a biological antioxidant. Exact requirements for this vitamin have not been established in the horse, and horses have the ability to synthesize their own vitamin C from glucose, so most feed manufacturing companies choose not to add vitamin C to their products. However, researchers have found that there are some instances in which the horse may benefit from supplemental vitamin C. Horses over the age of 20 are believed to benefit from the addition of vitamin C to the diet, and since vitamin C plays a role in collagen biosynthesis it may be a useful addition to the diet of a growing horse as well. A horse’s vitamin C supply may become depleted from intensive training programs, a virus or bacterial infections. The Journal of Equine Veterinary Science published work from researchers at Ahmadu Bello University which showed horses undergoing transportation were less stressed if ascorbic acid (vitamin c) was added to the diet.

The B-complex vitamins, also water soluble, include thiamine, riboflavin, niacin, biotin, folic acid, B12, B6, and pantothenic acid. Horses are capable of producing all of these vitamins in the hind gut through microbial synthesis, so again, most feed manufacturers choose not to add B vitamins to their products. Research may suggest otherwise. Scientists have found that microbial synthesis alone is not enough to prevent thiamine deficiency, therefore, the horse must consume thiamine through the diet. It is interesting to think about where the majority of vitamins are absorbed relative to where B-vitamins are produced. The order of movement through the digestive system is stomach, small intestine, cecum, large colon, small colon, and rectum. Most nutrient absorption occurs at the small intestine, however, B-vitamins are produced primarily in the cecum. Since these newly-produced B-vitamins cannot swim upstream to be absorbed, it is beneficial to provide B-vitamins via the diet rather than relying solely on microbial synthesis. It’s important to note that “minimum” vitamin requirements are very different from “optimal” vitamin requirements. Vitamin research in horses is extremely lacking, and scientists are finding that there may be a big difference in preventing deficiency symptoms (minimum requirement) and maximizing health, performance, and structural integrity (optimal requirement). It is through this mindset that many feeds designed for performance horses, growing horses, and senior horses now include an array of B-vitamins.

Microbes in the hind-gut of a horse are arguably the most important component to ensuring overall health and well-being. The microbial population of the horse is like the second brain of the animal. If the microbial populations are disrupted in any way the horse will pay a price whether that be in mild or acute colic, hind-gut ulcers, poor nutrient utilization, decreased performance, or even just an irritable attitude. Adding probiotics (living microorganisms) to a horse’s diet may help improve immune function, reduce instances of hind-gut ulcers, improve digestive efficiency, and help horses gain weight and hold body condition. Probiotic use in horses has become increasingly popular over the last several years, and it is important to note that all probiotics are not created equal. There are many strains of probiotics, and research is very limited when it comes to identifying the most ideal strains to use in horses. Another factor to consider is the ability of the probiotics to withstand manufacturing, storage, and then finally the shock of the stomach acid before finally reaching the hind gut of the horse. Some strains are certainly hardier than others, and some manufacturers employ unique and extensive processes for ensuring survivability of the microbes through the manufacturing process. Always look for a guaranteed analysis that lists CFU (colony forming units) to be sure that the product contains live microorganisms. Probiotics may be a very useful addition to the everyday diet of seniors and for horses under the stresses of training, travel, stalling, and limit-fed diets.

Equine nutrition is complex and ever-changing. It is a science. Nutritionists, researchers, and feed manufactures continue to challenge past practices in an effort to improve what we already know. Education is power, we can never know too much, and it is the responsibility of each horse owner to provide the best nutrition possible in the given circumstance. Always remember that quality forage is the first and most important component of a horse’s diet, never overlook the power of a solid forage program.