Kentucky Equine Research (KER) Horse Management Tips

Nutrition from Birth to Two Years of Age

A horse’s diet changes significantly between birth and maturity. Some individuals will not reach maturity until they are four, five, or even six years old. From a liquid diet to one that contains both forages and concentrates represents a significant spectrum. Proper nutrition establishes the foundation for future soundness and longevity, so its importance in the management of young horses cannot be overemphasized.

First Meals:

A foal’s first meal is usually colostrum, a yellowish, viscous fluid. The composition of colostrum is unlike that of milk, typically containing high concentrations of protein, attributed to greater levels of immunoglobulins and fat.

Timely ingestion of colostrum is vital to protect the foal against environmental threats immediately after birth and to stimulate the foal’s immune system. The newborn’s intestine is primed to absorb immunoglobulins in the first seven hours after birth, then decreases over the first 24 to 36 hours after birth.

When foals do not receive sufficient colostrum, and thus adequate antibodies, they may suffer from failure of passive transfer of immunity, a failure that may not be apparent until they are two to three days old. Evidence of passive transfer is determined by measuring immunoglobulins, specifically IgG, in the foal’s blood, serum, or plasma. Treatment of passive transfer failure depends on numerous factors; age of the foal, health of the foal, or immunoglobulin deficiency. Remedy this by oral dosing of colostrum through a nasogastric tube. A veterinarian may recommend intravenous administration of immunoglobulin, especially for foals nearing 24 hours of age.

After several nursing sessions when the udder has been drained of colostrum, the mare produces regular milk. Though mares cannot compete with even a mediocre dairy cow, at the peak of lactation, mares can produce 3% of their body weight in milk daily, with a 1,500-lb mare typically producing over 5 gallons of milk daily. This production satisfies the normal rate of consumption by full-term foals of 2.5 to 3.5 gallons of milk daily for light breed foals and 3.75 to 4.5 gallons of milk daily for heavier breed foals.

Foals grow rapidly during the first few months of life, quadrupling their weight in five months. Milk remains the staple of the foal’s diet until nearing three months of age.

Transition to Feeds:

Normally, it is unnecessary to supplement foals with concentrate during the first 90 days of age. At this point, introduce a fortified concentrate for growing horses, gradually increasing the daily intake to 1 lb. per month of age. If mares consume their ration from feed tubs that are accessible to their foals, it is acceptable for the foal to consume a portion of the mares’ meal.

Proper nutrient intake is vital during the 5 to 12 month old stage while the skeleton is most vulnerable to disease. Nutrition plays an important role in the pathogenesis of developmental orthopedic diseases as deficiencies, excesses or nutrient imbalances affect the incidence of physitis, angular limb deformity, and osteochondritis dissecans.

Feeding mistakes leading to developmental orthopedic disease include excessive grain intake, inappropriate feed for the available forage, and inadequate fortification. Rectify these three scenarios by feeding an appropriate grain mix fortified for the young, growing horse and feeding it at the correct intake. Young horses already suffering from developmental orthopedic disease should have their energy intakes reduced while maintaining correct levels of protein, vitamins, and minerals.

Foals that experience an exaggerated and sustained increase in circulating glucose or insulin due to a carbohydrate (concentrate) meal may be predisposed to osteochondritis dissecans. Field trial results by KER using Thoroughbred weanlings suggested a connection between high glucose and insulin response to a concentrate meal and osteochondritis dissecans.

Plasma glucose and insulin two hours after feeding were higher in weanlings with osteochondritis dissecans than in unaffected foals. Insulin/glucose ratios, however, were not significantly different. Based on the results of this study, feed young horses concentrates that produce low glycemic responses such as feeds with a proportion of the energy supplied by fat (vegetable oil and rice bran) and fermentable fiber sources (beet pulp and soy hulls).

Deficiency or excess calcium, phosphorus, copper, and zinc may lead to developmental orthopedic disease. Fortify the ration of a growing horse as hay and oats supply only 40% of a weanling’s calcium and 70% of phosphorus requirements, and less than 40% of its requirement for zinc and copper.

The ideal ratio of calcium to phosphorus is 1.5, never falling below 1:1 or exceeding 2.5:1. Excess calcium affects phosphorus status, particularly if the level of phosphorus in the ration is marginal; conversely, high levels of phosphorus in the ration will inhibit absorption of calcium, leading to deficiency, even if the amount of calcium present is normally adequate. Supplement high calcium forage diets with phosphorus. The ratio of zinc to copper should be 3:1 to 4:1.

Yearling Growth:

Supplementary concentrate amounts required to maintain a desired growth rate vary, and it is important to feed each horse as an individual. Feed easy keeper yearlings low-intake, low-calorie essential proteins, vitamins, and minerals. Conversely, large framed yearlings with growth potential can consume normal amounts of fortified concentrate. Developmental orthopedic diseases are unlikely to arise after 12 months of age. Lesions that become clinically relevant at this age have typically formed at a younger age; nevertheless, correct nutrient balance is important in the growing yearling.

To insure long-term health and soundness, strive for steady, even growth. Delaying rapid growth until after 12 months of age reduces the risk of growth-related developmental orthopedic disease. Later-born foals that are candidates for late fall sales or shows could follow a more moderate growth curve, typically resulting in large, well-grown yearlings with minimal joint problems.

Apply a rapid growth curve, concentrating weight gain over a short time period, to later-born foals targeted for earlier sales and shows. Though more susceptible to skeletal problems, if properly managed, more mature yearlings will be available earlier in the season. Spread the growth over several months rather than trying to achieve weight gain during the sale or show preparation period of 60-90 days.

Research suggests a relationship between the glycemic nature of feed and the incidence of skeletal problems in young horses. Diets high in starch and sugar increase blood glucose and insulin response after feeding, implicating them in the etiology of developmental orthopedic disease. Therefore, it may be beneficial to replace a portion of cereal grain energy with fat and fermentable fiber to reduce the glycemic response to concentrates.

Thoroughbreds typically begin race training as two year olds before their physical growth is complete. Therefore, feeding programs must meet the requirements of both continued maturation and increased exercise levels.

As two-year-olds mature, calcium, phosphorus and other minerals must build skeletal tissue and protein for muscle development. The skeleton responds to loading by adding bone and to idleness by losing some of this tissue. Changing from pre-training days of free exercise in a pasture to periods of stall confinement often leads to skeletal demineralization. Begin weight bearing track activity slowly to avoid injuring weakened bones with strenuous exercise.

As training progresses, bones become stronger and thicker as they adapt to the increased demands of work, however this change takes time. Feed grain products formulated for young horses in race training at the manufacturers recommended levels to insure the horse gets the needed fortification. Too much of some minerals are as harmful as too little. Keeping the right ratio of one mineral to another will prevent interactions that inhibit availability of the nutrients.

Dietary protein is important as horses increase lean muscle tissue in response to exercise. Not all protein is the same, however, and a feed product with a high level of protein may or may not provide the specific amino acids needed for growth and muscle development. Grains such as oats do not supply lysine, an important amino acid for these functions. Soy products in feeds formulated for young Thoroughbreds are one way to supply needed lysine.

Quality forage should be the basis of all equine diets. However, hay alone does not supply enough energy to support the needs of racehorses in training. Feed products offer additional calories from corn or oats, and fat sources, oil or rice bran. However, large grain meals may overwhelm the digestive system with starch, upsetting the microbe balance in the hindgut. Diets high in grain also increase the likelihood of developing gastric ulcers, especially if limited hay is available. Feeding three or four smaller grain meals throughout the day minimizes these risks.

Having hay readily available provides the young horse something to do as well as increasing the flow of saliva that buffers stomach acid and provides some vitamins, minerals, protein, and energy. An important function of hay is to keep the digestive tract functioning, as roughage is the horse’s natural food and the organs of digestion are designed to process a steady flow of fibrous material.

Fresh, clean water, and loose or block salt must always be available. For horses heavily exercised in hot climates, replace electrolytes lost in sweat with a supplement.

Active, athletic horses are at risk for skeletal damage. Bucked shins, bone chips and fractures are common among high-performance horses, but other problems, like bone bruises, are less ordinary. In Thoroughbreds, bone bruises usually occur in the front fetlocks, while in Standardbreds they frequently affect hind fetlocks.

Bone bruises, occurring from repetitive trauma during high impact work cause a bone to become denser and injure subchondral bone, the bone layer touching cartilage in weight-bearing joints. Subchondral bone contains many blood vessels that carry oxygen and nutrients to the bone and the underlying cartilage. Inflammation associated with these injuries cause degeneration of healthy subchondral bone, thus compromising its strength and integrity.

“In response to traumatic insult, the skeleton repairs itself by removing and replacing damaged bone. Bone changes are expected during training, but time is required for bones to repair and strengthen themselves,” explained Laura Petroski, B.V.M.S., veterinarian at KER.

“If insufficient healing time is afforded, the repair process is disturbed, resulting in thicker and less flexible subchondral bone. Damage may also occur to corresponding joint cartilage, compounding soundness. As horse owners know, cartilage destruction leads to the development of degenerative joint disease, or arthritis,” she continued.

“Observing poor performance, where the horse is not performing at its normal level is also an indication of problems. Localize the pain to the affected site by using nerve blocks, flexion tests, and palpation. At that point, radiography or advanced imaging is recommended,” said Petroski.

“Historically, veterinarians diagnosed this disease using radiography; however, changes noted on radiograph tend to be permanent changes and the disease is quite advanced at that stage,” she remarked. Today, nuclear bone scintigraphy and MRI are used to diagnose this disease. “This technology has been revolutionary in diagnosing, treating, and managing these horses properly. The earlier a treatment begins, the better the prognosis is for returning the horse to full work.”

Rest and recovery are the primary treatment of bone bruises. Unlike soft tissue injuries, allow horses with bone bruises free-choice exercise in a small field for several months, as blood flow promotes tissue healing; forced exercise is discouraged. Other treatments include anti-inflammatory drugs, intra-articular injection of steroids, pharmaceuticals to promote bone repair, and surgery.

Nutrition for horses having bone bruises begins with a well-fortified diet. Calcium is a critical nutrient, especially for young athletes. “While we cannot prevent bones from laying down more calcium, it is wise to protect other bones from weakening due to receiving insufficient calcium. The body will extract calcium from other bones if it is not available in the blood, changing and weakening the structure of those bones,” said Petroski.

In addition to promoting bone health, young horses in training benefit from receiving Synovate HA, a high-molecular weight sodium hyaluronate that has anti-inflammatory, lubricating, and shock absorbing properties for optimal joint health.

Injuries cause stress in horses, predisposing them to gastric ulcers and hindgut upset, explained Petroski. Changes in routine as treatment procedures begin create further stress. “I believe in preventing problems rather than treating them. We know that changes in routine may lead to distress and compromise to the gastrointestinal tract, it is best to be proactive in protecting the stomach and hindgut.”

Q&A: Optimal Nutrition for a Young Equine Athlete

Question

I have a three-year-old in training. Though just learning, we want him to push more from behind and develop more strength. Are aids like creatine legal, available, and recommended? Also, do you recommend glucosmine as a preventive supplement? What dietary additions or selections would you recommend to help develop strength?

Answer

For young athletes, start by ensuring the diet provides an optimal daily intake of energy (calories) and nutrients. To determine if sufficient amounts of energy are available, assess the body condition. Underweight horses should consume more calories; overweight horses should consume fewer calories. If a growing horse maintains its weight, or gains at an appropriate rate, it is consuming appropriate amounts of energy.

Next, double-check that sufficient quality hay or pasture is available to maintain digestive tract health and optimize forage as a source of energy and nutrients. We typically recommend 1.5% of the horse’s body weight be consumed as forage.

Then, determine how many pounds of manufactured feed your horse is currently consuming daily, in comparison to the manufacturers feeding directions. A common mistake horse owners make is not following the manufacturer’s feeding directions. These directions state product quantity to feed daily to meet the horse’s nutrient requirements.

Once an appropriate daily ration is determined, investigate other options to support optimal health and performance. Glucosamine, chondroitin, hyaluronic acid, and long-chain omega-3 fatty acids (DHA and EPA) provide positive effects for joint health.

To increase muscle in young horses, provide energy from a variety of sources, such as nonstructural carbohydrates, fat, fermentable fiber, and protein. Many products advertise improved muscle development, making it difficult to identify those backed by equine research. An example is creatine, though effective in humans, it is poorly absorbed by horses and fails to increase muscle creatine concentration or increased muscle mass.

During the first months of life, foals grow from about 10% of their mature body weight at birth to almost 50% of their mature body weight by weaning. To support this growth, the foal’s gastrointestinal tract must contain a population of appropriate intestinal microbes capable of adapting to significant changes in the foal’s diet.

“As foals transition from colostrum, to milk, and then to forages and concentrates, the gut microbiota must evolve to efficiently utilize the changing diet,” noted Kathleen Crandell, Ph.D., a KER nutritionist.

As stated by University of California, Davis veterinarians, “Foal health depends upon these microbes and can be affected by disruptions to the microbiota caused by infectious diseases or antibiotic treatment.”

Because diarrhea remains a significant cause of illness, even death in foals, understanding the establishment and development of intestinal microbiome continues to be an important research topic. To improve knowledge of the intestinal microbiome and its effects on foal health researchers collected fecal samples from 37 foals from birth to weaning and analyzed the fecal bacterial microbiomes.

Key findings of their study included:

• Composition of bacterial populations followed clear patterns throughout the early life of the foals in an age-dependent manner;
• As foals transitioned from milk to a diet of concentrates and forages, distinct changes in fecal microbial compositions were noted, beginning with bacteria that have the ability to metabolize milk and utilize fibrous plant material;
• Foals that developed diarrhea during the study period had recognizable differences in microbial populations; and
• Management style also affected microbial populations as differences in fecal bacteria were identified between foals raised on different farms.

“Future efforts will study less abundant bacterial populations that may also be essential to gastrointestinal health,” concluded the researchers.

About Kentucky Equine Research

For 30 years Kentucky Equine Research has continually developed innovative solutions to the health and nutritional challenges inherent in modern equine management. The results of studies conducted at its research farm, as well as advancements in equine nutrition from institutions around the world, are applied and thoroughly tested in the creation of KER products.