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Literature Review for the Supplement EVENT®: Breeding Horses Charlotte Brigden M.Sc. (Hons) Research and Development Coordinator for Horsesense
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1.0 Introduction
The range of supplements available for the horse is becoming increasingly more extensive. A variety of terms are used to describe nutritional supplements, including 'nutraceuticals' and 'ergogenic aids', and all imply a slightly different role. Feed additives are produced and marketed for many different reasons. There are, however, two fundamental rationales for the use of supplements:
a. To optimise the horse's diet and ability to utilise its' food: supplements that are produced for this include 'feed balancers', vitamin and mineral additives, and pro- and pre-biotics.
b. To enhance the functioning of body systems to improve performance and productivity: these products include blood supplements, hoof and coat enhancers, vitamin and mineral additives, calming agents, and fertility supplements, to name only a few.
When considering the use of supplements it is important assess the
potential benefits, safety implications and any alternative
options. In an ideal world every supplement would be produced
following an extensive series of independent studies. Financial
and practical obstacles often prevent this for horse
supplements. It is therefore the unfortunate reality that horse
supplements are produced on the back of data from other animals or
humans and the understanding of the scientists responsible for
developing the product. It is important for any user of a
supplement to understand the development of the product and how its
components work within the body.
2.0 What is Event®?
Event® is a full spectrum chelated trace element and vitamin drench, formulated specifically to the needs of the equine and designed to balance the variable micronutrient supply and availability from forage and hard feed. Its use on a monthly basis obviates the need for a 'cocktail' of supplements for hoof condition, blood cell count, etc. and avoids the inevitable over supply of elements common to such products. It is now recognised that maintenance of overall micronutrient balance in the body is more important than identification and correction of individual deficiencies, as excesses, causing induced or secondary deficiency, are more damaging that 'natural' or 'primary' deficiency.
3.0 The requirement for trace element supplementation
Trace elements are required for the functioning of every system within the body and the correct balance of these elements is essential. It is highly unlikely that the concentrate, forage and grazing provisions of horses will contain an appropriate balance of trace elements. Kapper et al. (1993) stated that the trace minerals in modern forages and grains would not meet maintenance requirements recommended by the National Research Council. It is widely recognised that the trace element content of pastures in the UK is highly variable and that certain regions are deficient in certain elements whilst containing other elements in excess. Supplementation of trace elements to ensure that the horse's diet is complete seems, therefore, to be essential.
It is almost impossible to be able to predict the rate at which the body utilises and excretes trace elements, as this will vary considerably depending on the condition of the horse, demands imposed upon the body and the composition of the diet. This means that it is very difficult to calculate the quantity of each element that the horse will need. The correct balance of the elements is, however, vital because potential complex interaction between the elements means that excesses of certain elements will result in 'locking up' of others. This essentially leads to secondary deficiencies and can also lead to toxicity. It is important to appreciate that, whilst the body needs to have access to an adequate supply of all the trace elements, provision of these elements above the required level can be as damaging as deficiency. One study reported that 78% of horses fed supplements are likely to receive excess copper, manganese and zinc, and that vitamin and mineral supplementation can therefore lead to an increased risk of excesses and subclinical toxicities (Jackson, 1996).
It becomes apparent that the ideal scenario would be for the body to have access to the elements as and when it needs them. To achieve this it is necessary to alter the way in which the elements are processed by the body, so that they are absorbed and stored within the tissues for use when required. Chelation of minerals helps to achieve this idealistic scenario.
4.0 Chelation of Minerals
The process of chelating minerals was developed commercially in 1968 and now plays an important role in human and animal nutrition (Manspeaker et al., 1987). During chelation a mineral is combined with one or more amino acids to form a stable biochemical ring compound. Amino acid chelated minerals carry a neutral charge and can be absorbed and metabolised 300 to 500% more efficiently than their inorganic counterparts (Manspeaker et al., 1987). The neutral charge of the chelated minerals ensures that they are not bonded into inactive compounds in the digestive tract. Inorganic minerals, being negatively or positively charged, can react with other compounds in the digestive tract and be eliminated in the faeces.
5.0 Specific requirements for trace elements and vitamins
The potential benefits that can be derived from the use of Event® are wide ranging, due to the importance of correct trace element and vitamin provision for every system of the body. It is appropriate to consider the possible advantages gained by the provision specific elements and vitamins for different classes of horses. It must be remembered that the benefits identified through the provision of individual elements would not necessarily be achieved if that element were supplemented on its' own, due to the potential interaction between elements and possible inability of the body to utilise individual elements, as discussed previously.
5.1 Breeding Horses
The greatest of care is taken to ensure that the diet of the breeding mare is optimal for the condition of the mare and development of the offspring. The nutritional requirements of the mare vary considerably with the stage of pregnancy and this is also true for her trace element and vitamin needs. A number of reproductive problems have been linked to trace element and vitamin deficiencies, although further research is needed in some areas.
Prior to conception sub-clinical deficiencies have been associated with irregular or absent oestrous cycles. This is not surprising due to the role that the elements play in hormone production. Conception rates are one of the most important considerations for the stud owner, not only as a measure of success, but more importantly to allow economical use of the stallions. Ovarian health and function are major limiting factors in conception. American researchers looking at the benefits of amino acid bonded materials have noticed increased ovarian activity, a more effective involution of the uterine wall and regeneration of the damaged endometrial tissue after parturition, and fewer persistent bacterial infections. (Manspeaker et al, 1987). Empirical data from the practical use of Event®, and reported by several large studs, has indicated that conception rates can improve up to one hundred per cent. It was also reported that the number of coverings had reduced dramatically.
During pregnancy it is during late gestation that the nutritional demands of the mare increase significantly. After seven months the energy, protein and mineral requirements increase. Trace mineral supplementation is very important at this time because the foetus stores iron, zinc, copper and manganese in its liver for using during the first few months of life. This nutritional strategy of storing trace minerals has been developed because the mare's milk is naturally low in these elements (Scott, 2001; Pagan, Jackson and Duren , 2002). At this time it is vital that the mare has access to trace element supplies so that her own reserves are replenished.
During lactation the mare has massively increased nutritional demands. Research has shown that although the mare's milk is naturally low in trace minerals, adding these nutrients to the mare's diet does not increase the trace mineral content of the milk (Pagan, Jackson and Duren, 2002). Studies investigating the supplementation of chelated elements during pregnancy, however, indicate that the trace element content of milk can be improved. Independent research by SAC (1996) using a chelated trace mineral and vitamin drench for pregnant ewes showed that benefit to the suckling young from dosing ewes in late pregnancy could not be bettered by dosing the lambs themselves. It was concluded that the stored elements were in fact transferred across the blood/milk barrier to the suckling young.
A national trial conducted by Dr Bridget Drew of ADAS (1992) indicated significant benefit to newborn calves through treatment of the dam in late pregnancy. This was attributed partly to the influence of the supplement on colostral antibody quality. This evidence, though extrapolated from other species, indicates that supplementation of Event® during pregnancy would enhance the nutritional and immune status of the foal. Circumstantial evidence from nearly a decade of use and reported by some of the UK's most influential breeders, has shown that foals are born more thrifty and vigorous, with noticeable physical advantages, such as incredible musculature and coat quality.
The benefits to the overall breeding success of mares that can be expected with a well balanced trace mineral and vitamin supplementation program would be invaluable to the horse breeder. The links between deficiencies of certain elements and specific breeding problems should also be highlighted.
Manganese is an important element to the breeding mare and deficiencies are implicated in reabsorption of foetus, death at birth and irregular oestrous cycles (Jackson, 1996). Iodine deficiency is also linked to abnormal oestrous. Deficiency of vitamin A is linked to impaired conception. Selenium deficiency is often associated with afterbirth retention.
The importance of trace minerals to foals lies primarily in the development of the immune system, physical development and potential for developmental disorders.
The proven cofactors for bone formation are vitamins A, C and D, copper and zinc, although manganese and others may be needed in small amounts (Bramlage, 2002b). Copper and zinc appear to act in the protection of newly formed bone. Copper supplementation has been found to be most effective in the prevention of the formation of poor quality bone, such as with physitis (Bramlage, 2002b). Copper and zinc deficiencies have therefore been associated with DOD (Bramlage, 2002a). Although such disorders are multifactorial problems and therefore cannot be eliminated or prevented totally through an ideal nutritional program, it is believed that nutritional supplementation of trace minerals can lessen the severity (Bramlage, 2002a). Studies at Ohio State (Knight et al, 1985; Gabel et al, 1987) reported that copper and zinc deficiencies were involved in the development of epiphysitis, contracted tendons and OCD lesions in yearlings. The use of Event® as a source of copper and zinc has proven to be valuable towards the prevention of epiphysitis, with studs reporting that they no longer needed to supplement these minerals. Gainsborough stud reported that blood tests showed that copper levels were high in the foals' blood after supplementation to mares.
When the potential costs of these nutritionally linked disorders are compiled with the potential benefits of effective trace mineral and vitamin supplementation, it is obvious that the discerning breeder cannot afford not to supplement.
Benefits of trace element and vitamin supplementation may also be seen in the stallion. Research has shown that amino acid bonded mineral can improve semen quality and quantity. Top breeders Andrew and Robert Nicholson administered Event® to their stallion William Curtis before collecting semen for freezing. At the age of twenty six there was concern about whether William would produce semen of a quality that would withstand the freezing and thawing process. When the semen was processed, however, Tullis Matson of Twemlows stud noticed that virtually all of the semen survived the freezing process and after thawing its' longevity was way above average.
6.0 Future research
Scientific trials into the efficacy of Event® are now being set up. The range of uses of Event® and the difficulty in quantitatively measuring many of the benefits of the product will provide obstacles in the comprehensive investigation of the product. One study is being set up at Writtle college to assess the effect of Event® supplementation on colostral antibody levels and trace element / vitamin status of mare's milk and the results should be available in 2003.
7.0 Safety implications
Event® does not contain any substances that contravene the rules of the Jockey Club. The chelation of the minerals helps to eliminate the risk of toxicity caused by excesses of certain elements.
8.0 Conclusion
The importance of the trace elements and vitamins for breeding stock is widely appreciated. Ovarian health and hormone levels are important determinants of oestrous regularity and conception for the mare. Semen production and quality can be influenced by trace element status. For the foal the trace element and vitamin levels of the dams' milk are important for immunity, growth and development, and for the reduction of developmental disorders.
The method of supplementation of the trace elements is very influential. The correct balance of elements is essential for absorption and metabolism. Supplementation of individual elements can lead to excess or toxicity of those elements, or more alarmingly, to the lock-up of other elements. Administration of all the trace elements in a chelated form appears to be the most effective way of ensuring that the body has access to the elements it needs. Event® may provide an easy and reliable method of providing the micronutrient requirements of breeding stock. This should help to ensure the general health and well-being of the individuals, as well as breeding success of adults and strong development of offspring.
9.0 References:
Bramlage, L. R. (2002a) Q & A with Dr. Bramlage. Conducted by Murphy, H. Q. http://www.ker.com/library/archive/paqpers/group1/QnA.HTM
Bramlage, L. R. (2002b) Investigation of farm wide incidence of bone formation problems in the horse. http://www.ker.com/library/archive/proceedings/sc93/InvestFarmWide/index.html
Drew, B. (1992) The effects of cow care on dairy cow fertility and calf viability. ADAS. Proceedings of the British cattle veterinary association.
Gabel, A. A., Knight, D. A., Reed, S. M. et al., (1987) Comparison of incidence and severity of developmental orthopedic disease on 17 famrs before and after adjustment of ration. Proc Am Assoc Equine Pract, 33:163.
Kapper, D. R., Mundy, G. D., de Ribeaux, M. B. (1993) Elements of nutrition I: of diet and digestive design. Modern horse breeding, 10 (6): 10-13.
Knight, D. A., Gabel, A. A., Reed, S. M. et al., (1985) Correlation of dietary mineral to incidence and severity of metabolic bone disease in Ohio and Kentucky. Proc Am Assoc Equine Pract 31: 445
Manspeaker, J. E., Robl, M. G., Edwards, G. H., and Douglass, L. W. (1987) Chelated minerals: their role in bovine fertility. Veterinary medicine (USA), Sept: 951-956.
Meyer, H. (1987) Nutrition of the equine athlete. In: Proceedings 2nd international conference on equine exercise physiology. Edited by J. R. Gillespie and N. E. Robinson. San Diego, California.
Pagan, J. D., Jackson, S. G. and Duren, S. (2002) Feeding the broodmare. http://www.ker.com/library/archive/papers/group1/BROODMARE.HTM
SAC (1996) Liqui thrive sheep, biological and economic influence on a hill flock. Mair and waterhouse.
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