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Friday
Sep042009

STUD NUTRITION WITH DEBBIE ODELL

healthy weanling

Stud Nutrition
Debbie Odell MSc Agric, Pr. Sci. Nat
Consultant Nutritionist – Vuma Feeds

 

debbie odellDebbie OdellAlthough feeding horses well has often been considered an art, budget and technology are important determinants of the viability of any stud farming operation. Sometimes there may be trade-offs to be made in terms of costs of feed, and the carrying capacity of land etc. In most cases though, where proper nutrition is neglected for the sake of short term cash flow considerations, one ends up more than compensating over the longer term. Prudent use of modern knowledge can go a long way to optimizing the profitability of a stud operation.

Feeding Broodmares

Broodmares are the lifeblood of a breeding operation and optimum nutrition ensures optimum production, in relation to longevity, fertility, and viability of the foal crop. Short cuts taken in feeding of broodmares, particularly in the last trimester of pregnancy, can have significant ramifications on the average sale price of young stock. For many studs it’s a numbers game, and Rands saved on cheaper feed may translate into Rands lost due to increased percentages of mare and foal mortality, difficult births, leg deformities, barren mares and developmental problems. Because of the time lag between conception and sale, the connection between mare nutrition and problems in young stock is often not made.

Non-lactating mares in early pregnancy can initially be treated as for barren mares, as their requirements do not increase significantly until the last trimester of pregnancy. This is not to say though that they can be thrown out and ignored – neither barren nor in-foal mares. This is where the art of feeding and the horseman’s eye become important. These mares should be kept reasonably covered, not thin but not excessively fat. Energy balance is the most important factor at this time, with protein, vitamin and mineral requirements remaining in steady state. Changes in body condition can be made purely by altering the energy supply. Good quality roughage and/pasture can be supplemented with a relatively low protein commercial stud feed to control body condition.  It may be useful to employ some form of body condition scoring system.

The last trimester of pregnancy accounts for about 65% of the foal’s birth weight. This is when the foal is developing rapidly in terms of body weight, and it is a critical time for skeletal development. It becomes essential to increase the mare’s supply of protein, energy, vitamins and minerals during the last trimester, to allow for optimum foetal growth and development. Nutrient deprivation at this time has been implicated in various problems including leg and bone abnormalities in foals, as well as low birth weights. Low birth weights significantly affect the viability of the foal and of course bone abnormalities affect the achievable sales price. At this stage, pasture and roughage should be supplemented with a concentrate specifically formulated for broodmares. It is also important that mares do not foal too fat, as overly fat mares may also contribute to skeletal abnormalities in foals at birth.

After foaling, the mare continues to provide for most of the foal’s nourishment by means of milk production. Lactation is a metabolically expensive process and nutrients must be supplied to accommodate this. A broodmare concentrate should sufficiently provide these requirements with amounts fed being determined largely by mare condition. After foaling, mares will usually (temporarily) go into an energy deficient state, meaning that the energy they require to produce milk is more than what they can extract from their diet. In these cases, mares may lose weight. It is the task of the stud man to ensure that the mare is on an increasing plane of nutrition at this time, to ensure that milk production is not affected by the negative energy balance, that the mare has the capacity to re-conceive, and that she gains back the weight lost before the last trimester of her next pregnancy. It is well-accepted that mares on a low or decreasing plane of nutrition have lower conception rates than those on an increasing plane of nutrition.

Feeding Young Stock

Whether or not to provide a creep feed for foals may be contentious and largely depends on the preference of the stud manager. However, if one is supplied, it should contain a relatively high level of quality protein, as well as optimum vitamin and mineral levels. Growth is rapid during the first year of life and it is at this time that bone, cartilage and tendon are being deposited and strengthened. Protein is never as important to the horse as it is at this time, and ironically, this is the time when many stud managers are reluctant to supply it. A horse, at any stage, has no requirement for a “percentage” of protein, but rather a certain mass of protein per day. The percentage protein feed supplied should be calculated by the requirement in grams divided by the amount of feed to be supplied. Since the intake of young horses is low, it follows that the “percentage” protein of young stock feeds will be relatively high.

In addition, quality of protein is important. Although much work still needs to be done on the composition of the “ideal protein” in horses, it is generally accepted that lysine is the first-limiting amino acid, followed by methionine and perhaps threonine. It follows then that a diet containing sufficient total protein but which is low in lysine, will make the balance of the protein unavailable for effective utilization. To use the Leibig’s Barrel analogy, you can only fill a barrel to the level of the shortest segment. Any protein supplied in excess of the first limiting amino acid is effectively wasted. Also remember, especially when analyzing feeds and pastures, the “crude protein” is actually a measure of the amount of nitrogen in the feed and the assumption is made that that nitrogen is all assimilated into protein. The measure gives no indication of the amino acid profile of the feed, and in relation to highly fertilized pastures, it gives no indication of the levels of nitrogen which are not incorporated into protein – the so-called non-protein nitrogen fraction or NPN. This NPN is of greater value to ruminant animals as it can be utilized by the rumen microbes to make microbial protein. Microbes in the hind gut of the horse may do the same thing, but digestion of microbial protein by horses is minimal due to the hind gut fermentation site in the horse.

Ideally, a steady growth rate is desirable in foals. This is often difficult as seasonal variations in pastures in terms of both energy and protein can account for sudden growth spurts, and some accompanying problems. As far as possible, these seasonal variations should be counter-balanced by judicious supplementation. Vitamin and mineral supply are also vital during this time as certain of these nutrients have been implicated in developmental problems in foals. As with all nutrients, it is the balance that is important, as too much of one nutrient may be counterproductive with another. Mineral nutrition in particular is a complex subject, as a multitude of interactions may occur and these may not yet be fully understood. The advice and products of a reliable feed company or nutritionist will be invaluable at this stage.

Sales Preparation

The current market dictates that the objective behind preparing a yearling for sale must be to produce a well grown, athletic looking horse with good, but not excessive cover. This entails a judicious feeding routine combined with an element of exercise. Walking of young stock is helpful for muscle development, and a mechanical walker must surely ease the labour burden. Sales prep should commence at least 3 months prior to the sale date. The amount of concentrate that needs to be fed depends largely on forage quality and availability. It should be remembered that the yearling is still growing and its requirements for protein and energy still need to be met. The balance needs to be achieved between supplying enough energy to put on the necessary cover, without compromising bone growth. As the bones are still immature, and because the introduction of exercise initiates significant bone remodeling, the diet protein and mineral content is critical.

The importance of individual assessment cannot be overemphasized. Fillies tend to fatten quicker than colts, and late foals may be at a disadvantage as they will have to be pushed that little bit harder to reach the desired result on time. Oil can be a useful ingredient for sales preparation. The energy in oil is about two-and-a-half times that in the equivalent weight of grain, so it can be used where feed intakes cannot be increased. Oils with a significant Omega 3 fatty acid component can be helpful due to their tendency to mitigate inflammatory responses which may occur with the onset of exercise. 

Feed components

Roughage

Good quality roughage remains the backbone of any feeding regime. The more roughage is ignored, the more problems are encountered. In the ideal world, the stud farm should produce the majority of the fodder required for horses, with the balance being supplied by a relatively small amount of concentrate. This is not always possible though, depending on land area available and stocking densities. Fodder production also varies seasonally, and some roughage may need to be strategically purchased. Ideally though, for optimum gut health, the average horse’s diet should consist of roughly 30% concentrate and 70% roughage. At strategic stages in the horse’s life, it may not be possible to meet all the horse’s needs on this regime and the amount of concentrate will need to be increased. The ratio of concentrate to roughage at certain times may need to be up to 70:30, however once this ratio is increased, the likelihood of problems such as colic, acidosis and laminitis increases considerably. 

Horses are grazers and trickle feeders which means for optimum health they should have constant access to feed. There is no replacement for good quality pasture, however, allowances must be made for the composition of certain common grasses. One of the most common grasses used as pasture for horses is kikuyu grass. Kikuyu needs particular care as, not only does it have an inverse calcium: phosphorus ratio (P > Ca), it also tends to accumulate oxalates which may be present in the soil. These oxalates bind with the calcium forming an insoluble, indigestible complex, further reducing the amount of calcium available. This is of particular interest to the stud breeder, as the two most important times for calcium supply are in growing horses and in lactating mares. This inverted Ca:P ratio, over a period of some months, will cause a condition known as nutritional secondary hyperparathyroidism (NSH), more commonly known as “big head” or “bran disease”. The most observed symptoms are changes in the facial bone structure, sometimes accompanied by intermittent lameness. This needs to be managed in a stud herd by the use of a reliable stud feed, and supplementation with suitable calcium-based products.

Concentrates

Concentrates need to be added over and above the roughage fraction to supply those nutrients not supplied by the roughage. Concentrates can be situationally formulated, or a commercial product may be used. Feed companies will be able to supply recommendations as to how best to use their products. The feed will be of a specified protein value and proteins may be of animal, marine or vegetable origin. Protein sources which are animal in origin may be of value for their amino acid profile, but their use is frowned upon in horse feeds, and is illegal for use in ruminant feeds. Protein sources which are vegetable in origin are widely used in horse feeds and include soya, sunflower, lupin and maize gluten products to name a few. These are valuable sources of amino acids but synthetic amino acids may be strategically utilized to make up for raw material shortfalls

Of equal importance in the formulation of a concentrate is the energy level. The declaration of energy levels is not required on our local feed labels, for a number of reasons, however, it is important to know at least where the feed sits on the energy scale. Although two feeds may have the same protein level, the energy levels may be vastly different, so be sure to choose a concentrate with the desired energy level for the purpose intended.

Fibre is also an element of a concentrate diet, and as a rule of thumb, the higher the crude fibre content, the lower will be the digestible energy (DE) value of the feed. The newest buzz word is the so-called “super fibres”. These include beet pulp and soya hulls. They do not include common husk byproducts of the milling industry.

Vitamins and Minerals

Since vitamins and mineral levels need to be balanced for feed intake, it is not unusual for commercial hacking meals, where the expected feeding rate is low, to have a denser vitamin and mineral pack than a racing feed, where expected intake is high. The vitamin and mineral packs in commercial feeds are really the difference between a good feed and a great one. Quality of the individual nutrients included in the pack is important, as is the assurance that the pack is free of undesirable substances, such as ionophores, which are commonly used in ruminant and poultry rations but are deadly to horses. Balance is all important in the stud operation and vitamin and mineral levels are crucial for so many aspects of the operation. Traditional inorganic minerals are commonly used; however there are organic versions of certain of these minerals, which have higher absorption efficiency. Here is perhaps another opportunity for a trade-off between cost of these organic forms and the benefit of increased absorption.  Vitamins are also an expensive part of the ration, but the benefits of good levels of vitamin A, vitamin E and biotin are irrefutable in stud rations, and there is evidence to suggest that vitamin C is useful in laying a good foundation for bone development.

Formulation Practices

Some commercial operations make use of the traditional least cost formulation practice. This method is useful when feed companies are diversified and may make use of pockets of raw materials that become available from time to time. Under these circumstances, one batch of feed may differ significantly from the next in terms of ingredient usage, even though they meet specifications. When feed is in meal form, these changes may be visible to the naked eye, and may manifest in feed inconsistency between purchases. However, when the feed is in pellet form, the formulation changes are difficult to notice but they may contribute to digestive upsets, particularly in horses receiving a high proportion of concentrates in their diet. Pelleted diets have also been implicated in the incidence of ulcers.

More consistent feeds are available where optimum cost formulation is applied and stricter parameters insofar as ingredient inclusions are imposed. These feeds are generally more expensive, as ingredient inclusions cannot be changed on the whim of the market. Ascertain your feed supplier’s philosophy on formulation techniques, and ensure that it coincides with your own, before making the decision purchase.

It goes without saying that the feed company bears a responsibility to ensure that the raw materials they employ are of suitable quality and are free from harmful substances. However, the raw materials used are the product of farming operations, and it is another important step in the chain that ingredients are sourced from suppliers who can guarantee good and sustainable farming practices.

In summary, nutrition is the backbone of the stud operation, and accounts for a large part of the operational costs. Optimal nutrition is the goal, and there is no substitute for the eye of the horseman employed alongside the modern science of nutrition. There may be cost trade-offs to be evaluated from time to time, but nutritional shortfalls usually come at a price in the longer term. Reputations are built with consistent effort over a period of time, but the market is unforgiving, and shortcuts can be the most effective method of eliciting a new reputation overnight. Good quality fibre is a critical factor, with concentrates to be used where and when necessary. Concentrate: roughage ratio is important in optimizing gut health while supplying the nutritional needs and eliminating feed related medical emergencies. Commercial feed companies can provide suitably formulated feeds, or these can be mixed on the farm. Either way, it is important that the ingredients used are of the best quality available and free of harmful substances, including moulds and mycotoxins.

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