Breeding Farm Recommendations

Nutritional Recommendations for the Breeding Farm

by: Daniel J. Burke, Ph.D., Director of Tribute Equine Nutrition at Kalmbach Feeds

Most nutrition programs on a breeding farm are targeted toward managing the late gestation broodmare. This is appropriate, as the most rapid growth of the fetal foal occurs during this time. However, nutrition is important for more than just the late gestation broodmare. It is vital for helping open mares to conceive, during early gestation for the early fetal development, for allowing stallions to maintain their body weight and vigor, and for sucklings, weanlings, and yearlings to continue growing sound to their genetic potential.

Managing nutrition on a breeding farm is not just feeding what comes in the bag. It’s understanding the forages that are being fed and knowing about the nutritional requirements of the various horses so that the right feeds are being fed in the right amounts to allow for the optimal performance of each horse at the most reasonable cost to the owner.

Feeding Stallions

A stallion should be in good physical condition at the beginning of the breeding season. This means he needs to be in good flesh (body condition score 5 or 6) and physically fit. A stud in poor body condition (too thin or too fat) or one who’s out-of-shape won’t breed as well, and mares won’t settle as easily. This costs additional time and money.

Nutrient requirements for breeding stallions are often overestimated. A diet balanced for a light working horse typically has enough protein, vitamins, and minerals to meet the breeding stallion’s needs. The only nutrient requirement that may go up significantly is energy. When feeding enough of a properly balance diet to maintain the horse’s ideal body weight, a reflection of adequate energy intake, the levels of all other nutrients will meet the stallion’s requirements.

The stallion’s activity level will often increase (pacing and breeding behavior) and his attention span for feed will sometimes decrease during the breeding season. This means he needs to receive more calories in a smaller meal, and that meal needs to be highly palatable to encourage him to eat. A well-designed fat supplement added to a sufficient diet, will increase the caloric content of the diet without substantially increasing the volume of feed being fed. Turning the stallion out in a small paddock with grass will also encourage him to eat more and help maintain his body condition. During the non-breeding season, feed him according to his activity level (maintenance or working). This likely will require a reduction in concentrate intake.

Click here for chart.

Longer-chain omega-3 fatty acids like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have shown promise in improving fertility in stallions, especially those with lowered conception rates using cool-shipped semen.

Feeding Open Mares

The open, or non-pregnant, broodmare needs to be in moderate flesh (body condition score 5 or 6) during the breeding season. A mare that is too thin will not conceive quickly or hold a pregnancy well. Obesity does not seem to affect conception rates in horses, but it has other negative drawbacks on the mare’s health. While she could be fed as a maintenance horse at this time, additional protein, with special attention paid to critical amino acid levels, vitamins, and minerals may help her to more easily conceive and maintain a healthy pregnancy.

Feeding Pregnant Mares

Historically, many thought that the early pregnant mare could be fed like an open mare until the last 3-4 months of gestation. Research has shown that this practice may actually predispose the foal to Developmental Orthopedic Diseases (DOD). Trace nutrients, many of which are critical to normal bone development, are stored in the liver of the developing fetus. Mares not receiving adequate nutrition during gestation may not be able to shunt enough nutrients to support the developing foal during the last trimester - the most rapid growth phase.

Special attention must be given to the diet of the pregnant mare from conception to foaling, especially for essential amino acid balance and the levels of copper, zinc and possibly manganese. Current NRC (2007) recommendations for copper and zinc are 100-125 mg and 400 mg/day, respectively. Some research suggests copper levels of 350 mg and zinc levels near 800-1,000 mg/day may reduce the incidence of D.O.D. The current NRC (2007) only addresses a single amino acid, lysine. The lysine requirements have been increased somewhat from previous publications without a correlating change to the overall protein requirement, suggesting increased attention to protein “quality” or amino acid balance instead of protein “quantity”. Researchers will learn more about other essential amino acids as our knowledge base increases.

Many pregnant mares are able to obtain enough calories from good quality forage to maintain or even gain weight. No forage, neither grass or legume, hay or pasture, will supply all the nutrients needed by the broodmare for her own maintenance much less the trace minerals needed for sound fetal development. If the mare’s diet is deficient in specific nutrients, the fetus can pull many of the nutrients it needs from the dam’s body, up to a point. This is why we generally see a lower number of nutrition-related DOD’s in a mare’s first or second foal. If the mare’s depleted body reserves are not replenished, deficiencies can occur in their future foals and eventually will affect the reproductive performance and health of the mare herself.

As stated above, some mares maintain their body weight more easily than others. Traditional feeds, designed to be fed at ¾ to 1 pound/100 pound of body weight and high in cereal grains and molasses, will often result in those types of mares becoming too fat. To keep the calories in a mare’s diet at a minimum so that she does not become obese but still assure adequate nutrition, concentrates have been formulated which contain three to five times the amount of critical amino acids, major minerals, trace minerals and vitamins found in most inexpensive horse feeds. These feeds are often called ration balancers. Pregnant mares weighing 1,000 pounds can be fed a minimum of two (2) pounds per day of this type of product. This can supply the nutritional equivalent of six (6) to ten (10) pounds of typical horse feed without the extra calories. Well designed ration balancers will be based on the type of forage your horse is eating (i.e. grass, grass/legume mix, or legume).

Some interesting research has been conducted at Virginia Tech on a concept termed “fetal programming”. Basically, it is attempting to define the effect of the pregnant mare’s diet on the foal’s physiology. One as yet unpublished finding was that mares fed a high non-structural carbohydrate (NSC – sugar + starch) diet tended to have foals with increased insulin resistance. This condition may predispose foals to D.O.D.

The exact definition of “low NSC” or “low sugar/starch” has not been agreed upon, but may be in the area of 15-20% in the TOTAL DIET (hay and concentrate combined). This level of NSC is very difficult to achieve in diets high in cereal grains and molasses – typical inexpensive “sweet” feeds. Most concentrates that are low in NSC are pelleted, as they must be formulated with highly digestible fiber sources, like beet pulp, soybean hulls and dehydrated alfalfa meal, and fat, in the form of soybean, flaxseed and rice oils.

Feeding Lactating Mares

Lactation is the most nutritionally demanding state a mature horse can be in, outside of intense race training. There is a SIGNIFICANT increase in the requirement for ALL nutrients, including energy. This is one of the reasons we often see thin lactating mares – the correct diet adjustments have not been made. Feeding high quality forage will reduce the amount of concentrate you will need to be fed per day. Having the forages analyzed and balancing the total ration based on the information will assure all nutrient requirements are met and that you are providing optimal nutrition in the most economical way.

The quantity and quality of mare's milk is primarily genetic, but her nutrition can have an important impact. It is important to make sure the mare’s daily intake of nutrients is AT LEAST equal to the nutrients she is putting out in her milk. If we do not match this nutrient input-output requirement, we cause the mare to deplete her body stores of many nutrients. This negative nutrient balance will eventually reduce the nutrients in her milk and adversely affect the foal. If the mare is not getting enough calories, she will lose weight. If she is low in other critical nutrient, unfortunately, we may not realize it until the foal begins to show poor condition, excessive condition and/or signs of D.O.D.

The amount and composition of mare’s milk also changes with the stage of lactation. Milk production gradually increases from foaling to 6-8 weeks post-foaling - so will her need for increased nutrition. After 8 weeks or so, her milk quantity and quality will gradually decline, as will her nutritional requirements. During this entire time, the foal is growing, and may be growing rapidly, so we must provide the foal a well-designed diet to provide what the mare’s milk is not. Recognizing this allows us to match the mare’s nutrition to the natural changes in her milk as well as provide the proper nutrition above what the milk is supplying to the foal in the form of a “creep feed”. (discussed later).

The chart below shows the percent increase over maintenance for critical nutrients for the mare in early lactation. Maintenance is 100%.

Click here for chart.

Important to note is that the increase in the demand for calories (D.E. = digestible energy) is proportionately LESS than the increases in crude protein (C.P.), lysine, calcium and phosphorous. As previously discussed, the demand for copper and zinc may also increase more than the need for calories, though it is not reflected on this chart, as the chart is based on strict NRC 2007 requirements.

What does this mean?? It means merely feeding more of a feed designed for “all horses” or non-breeding horses WILL NOT meet the requirements of the lactating mare. The lactating mare requires a diet significantly different than one designed for other types of horses. As you will see, the same is true for young, growing horses.

Feeding the Suckling

As discussed above, many factors affect the amount of milk a mare produces and the nutritional composition of that milk. As the milk is the primary source of nutrition for the foal, especially in the first few weeks, the milk the mare produces has a direct effect on the growth and health of the foal.

During the early stages of lactation, the average mare will produce about 3% of her body weight per day in milk. For example, a 1,000-pound mare will produce approximately 30 pounds, or 4 gallons, of milk per day. As the mare’s milk production decreases over time, hunger encourages the foal to begin eating dry feed. The design of the feed the foal consumes is critical to it realizing its genetic potential.

Foals often show interest in solid feed at one to two weeks of age. At this time it is recommended you provide a “creep feed” in a creep feeder or in some area separate from the mare, to prevent her from stealing the foal’s feed.

Ideally, the creep feed will designed complement the mare’s milk, not to complement forages as in adult horses, as forage is a minimal part of the young foal’s diet. In addition, early in life, foals cannot effectively utilize vegetable-source protein (i.e. soybean meal, linseed meal, alfalfa), so a milk-based concentrate is best. Allowing the foal to steal the mare’s feed is unavoidable and acceptable, but the foal cannot eat enough or efficiently utilize a feed designed for an adult horse to prevent issues. The creep feed must meet the foal’s increasing mineral requirements due to growth as the mineral density in the mare’s milk decreases. After about 3 months of age, the foal can be transitioned from the milk-based feed to a more traditional vegetable-protein-based concentrate, but it must be designed with special attention to amino acid balance and levels of critical minerals and vitamins, especially calcium, phosphorous, copper and zinc.

Essential amino acid balance determines the “protein quality” of a feed. Good protein quality is required to maintain optimal, sound growth in the horse. The only amino acid currently addressed by the NRC 2007 is lysine. Though it is a good indicator of protein quality, other essential amino acids, like threonine, methionine and cystine may help improve true growth in horses. Some data exists on what the levels for these other amino acids may be, but it is not sufficient for the NRC Horse Nutrition Committee to publish a requirement. We know from other species, the balance between these nutrients is critical.

The ideal calcium:phosphorous ratio in the diet of the young, growing horse is between 1:1 and 2:1, hay and concentrate combined. Legume forages, like alfalfa and clover, may have calcium:phosphorous ratios as high as 8:1. The only way to correct this imbalance is to have the concentrate contain more phosphorous than calcium. Very few products have this unique feature. It is unlikely with average to good quality forages that either calcium or phosphorous would be deficient – imbalance is the most likely issue.

We have addressed the issue of copper and zinc levels previously. There is evidence that copper levels 3-4 times higher and zinc levels 2-3 times higher than the current NRC 2007 recommendations may help alleviate the incidence of D.O.D in many situations, especially programs with faster-growing horses. Such levels can be beneficial and are far from maximum tolerable levels, which, according to NRC 1989, are 12 times the requirement for zinc and 80 times the requirement for copper.

In the case of an under-producing mare or an orphan foal, the foal may be offered a mare’s milk replacer. Signs of an under-producing mare can be an unthrifty foal, one that is not growing as expected or one showing signs of D.O.D. Some milk replacers have to be bottle fed, while others can be offered in a bucket in the stall or paddock. The milk replacer can be used in combination with a well-designed creep feed.

If you see signs of D.O.D. (i.e., physitis (swelling of the growth plate near the ankle or near other joints) or “contracted tendons”), before the foal is 8 weeks old, it may indicate the diet of the pregnant mare is not sufficient. Her program must then be changed to prevent her next foal from having these same issues. If D.O.D. symptoms occur between 8 and 16 weeks of age, the feeding program of both the lactating mare and the foal should be analyzed.

NOTE: Hair analysis to determine the adequacy of the horse’s diet has not been proven to be accurate. Analysis of blood sample for nutrients is only valid for certain nutrients (Phosphorous, copper, zinc and selenium). Others, like calcium, are subject to “homeostatic” mechanisms which maintain certain blood levels even in the face of dietary insufficiency. Thus, analysis of the ENTIRE diet, forage and concentrate, is the best method to assess your feeding program.

Feeding the Weanling and Yearling

There are many opinions on when to wean. A complete discussion of this topic is beyond the scope of this presentation. When the decision is made to wean a foal, it is important that the foal is eating sufficient solid food to sustain its genetic growth rate. Some individuals will slow down their growth rate at 6 to 12 months, while others continue to grow rapidly. It is important to feed the horse’s physiology (which determines the growth rate), not necessarily it’s chronological age. Many yearlings grow as fast as weanlings, and must be fed a diet to support such a growth rate in a sound manner.

A common belief is that high protein diets cause D.O.D. This is not true!! Current research suggests that diets excessively high in calories, especially from NSC, can contribute to D.O.D., especially if the balance of calories to the other critical nutrients in the diet is not correct.

An approach I call “ground-up” nutrition, starts by meeting the growing horse’s non-calorie nutrient requirements – amino acids, minerals and vitamins – then adding a calorie source as needed to maintain desired body condition. This can be accomplished by feeding a ration balancer designed for the forage being fed at recommended levels.

Then, if more calories are needed for body condition, we can add oats, or more appropriately, a fat supplement or complimentary low NSC (“low starch”) product. This approach might be slightly more expensive in cost per day, but can save many times the cost in veterinary bills and lost sales value due to D.O.D.

The chart below shows the percent increase over maintenance for critical nutrients for the 6 month old growing foal. Maintenance level is 100%.

Click here for chart.

As in the lactating mare, we again see that the requirements for crude protein, lysine, calcium and phosphorous increase faster than the energy requirement (D.E.). Young, growing horses require a specially designed diet to meet their unique needs.

With many poorly designed feeds, horses may have to be fed more to meet the requirements of non-calorie nutrients, thereby developing excess body condition, which can aggravate D.O.D. Try to keep young, growing horses in moderate flesh, body score of 5-6. Then, monitor body weight with a scale or weight tape every 2-4 weeks, so adjustments can be made as growth rate increases or decreases.

Factors involved in Developmental Orthopedic Disease (DOD):

There are several factors involved in growth related skeletal problems. They include:

1. Genetic Predisposition - poor leg conformation and/or the inability to absorb certain nutrients. Genetics is one factor that we cannot change after the fact. The time may come when certain individuals may need to be culled from the breeding herd, because proper management and nutrition cannot overcome the genetic issues.

The remaining discussion will focus on the two factors within our control, management and nutrition.

2. Management plays a role in growth related problems. Two extremes are:

a. when activity is limited to total confinement, and

b. when excess trauma is induced from

1. too much body weight,

2. forced exercise, and/or

3. drought conditions in the pasture

Normal bone development depends, in part, upon the foal bearing normal weight on its limb, including movement. FREE-EXERCISE is critical to normal bone development.

3. Nutrition has been discussed at length above.

Conclusion

Make sure the TOTAL DIET (forage and concentrate combines) is balanced for the horse in question.

The key horses in a breeding program for which nutrition is critical to maintaining the individual’s health and developing sound, healthy foals:

Pregnant mare beginning at conception.

Lactating mare, especially in early lactation (1st 3 months).
Suckling foal – “creep” feeding can provide distinct benefits.
Weanling/Yearling – monitor growth rate and keep young horses in moderate body condition (body score 5-6).

Most likely nutrients to be imbalanced or deficient:

Essential amino acids (starting with lysine).