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Nutrition: work

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Podcast: Nutrition: work

Introduction

  • As the horses work load increases its nutrient requirements increase.
  • The concentrate proportion of the diet tends to increase to meet the horses increased requirements.
  • The diet should be appropriate for the current workload not for future work.
  • Overfeeding and underfeeding can both contribute to poor performance.
  • Feeding and training should be increased gradually over a number of weeks in preparation for competitions or hard work.
  • Horses in work may consume up to 3.5% of their bodyweight as food/day.
  • The concentrate ration should be reduced when the horse has a day off or a lighter work period.
  • When large amounts of concentrates are fed it is important to consider the risk of laminitis. Providing small meals should help avoid the problem.
  • As fitness increases the horse's appetite often declines. Use more concentrated nutrient sources to provide the required nutrient levels in a smaller volume of feed.
  • Pulmonary function is thought to be the limiting factor to athletic performance. Forage should be dust free to limit damage to the respiratory system and maximize pulmonary capacity. Haylage or soaked hay are commonly used.
    Print off the Owner factsheet on Nutrition - keeping your horse on top form  to give to your clients.

Energy

  • Energy   Nutrition: energy  is the dietary factor most affected by exercise
  • The intensity of work influences which energy sources are utilized.
  • Different proportions of each energy source are therefore recommended for horses competing in different disciplines.

Disciplines

Endurance
  • A diet of between 8 and 12% fat is suggested to improve stamina and endurance.
  • The type of fiber fed is important as it influences water availability and absorption in the hind gut. Hay tends to bind and retain water and so can be used before an endurance event to retain water in the digestive tract. Sugar beet also binds water but is easily fermented releasing the water for absorption. Sugar beet is therefore often used during endurance rides.
  • It is suggested that a high glycemic meal, the night before an endurance event, will top-up liver glycogen stores.
  • Feeding grain 1-4 h before a ride should be avoided as the rise in insulin will result in limited fat utilization during the ride.
  • It is also stated that feeding grain immediately before or during a ride will not disrupt fat utilization as exercise will elevate epinephrine   Epinephrine  which depresses the release of insulin.

  • Dressage and show-jumping
  • A diet containing between 5 and 8% oil would be sufficient to enhance stamina and would be particularly beneficial for horses competing on consecutive days.
  • Plenty of forage is required to maintain normal, healthy gut function.
  • Horses competing in these disciplines may not require a high energy performance feed. If a low energy feed is used it is important to use a balancer or supplement to provide the minerals   Nutrition: minerals  , vitamins   Nutrition: vitamins  and essential amino acids   Amino acids  required for harder work.

  • Racing
  • One study found that Thoroughbred   Thoroughbred  racehorses who were adapted to a fat supplemented diet had increased muscle glycogen stores.
  • The timing of grain feeding may not be as critical for racehorses as fat is not the primary fuel used during a race. This area does, however, require further research.
  • As excess weight increases the amount of energy required to move the horse, forage is often restricted prior to racing to reduce gut fill. Ideally all horses should still receive the equivalent of 1% of its bodyweight as forage/day.

  • Three-day eventing
  • Witholding grain before the speed and endurance phase on cross country day may be beneficial in stimulating the use of fat as an energy source and sparing glycogen stores.
  • Glycogen stores should be replenished after completion of the speed and endurance phase with a high glycaemic meal in preparation for the final day's show-jumping. The timing of this meal requires further research.
  • Feeding 1% of bodyweight as forage should keep gut fill and excess bodyweight to a minimum whilst maintaining healthy gut function.

Vitamins, minerals and electrolytes

  • Vitamin E   Vitamin E  acts as an anti-oxidant - performance horses should receive 800-1200 iu/day. Additional vitamin E is recommended when extra oil is fed. Exact recommendations have not been established but an additional 100 iu vitamin E/100 ml of oil added to the ration.
  • The performance horse may require extra B vitamins as a low forage intake may compromise hind gut function and therefore B vitamin synthesis.
  • Selenium   Selenium  is a constituent of anti-oxidant enzymes responsible for counteracting the production of free radicals and so harder exercise increases requirements.
  • In one study horses with resting packed cell volumes below 34% defined as anemia, had no evidence of impaired iron status. Low levels are suggested as more likely to be an indicator of infection.
  • Sodium, potassium, chloride and magnesium are collectively known as electrolytes and are lost in sweat and urine during exercise.
  • The amount of sweat lost depends on the length and intensity of exercise and environmental conditions. The longer and harder a horse works the more sweat, and therefore electrolytes, he will lose.
  • Electrolyte supplementation is advisable for all working horses and should be administered according to the volume of sweat lost.

Dietary cation-anion differences

  • The cations sodium and potassium and anions chloride and sulphur, are the most influential ions involved in the regulation of osmotic pressure in body fluids and in maintaining acid-base status.
  • The dietary cation-anion difference (DCAD) has been shown to influence performance.
  • One study found that mature horses with a high DCAD diet were significantly faster over a mile at heart rates of over 200 beats/min than horses fed a low DCAD diet. Blood lactate concentrations were higher in horses on a high DCAD diet suggesting that lactate was cleared from the working muscle more efficiently due to a higher concentration of H ion acceptors.
  • Cereals regularly used in horse feeds have a typically low DCAD.
  • Forages generally have a higher DCAD than cereals.
  • The quality of hay largely determines its DCAD with more mature hays, with a greater lignin content, having lower DCADs than early cut hay.
  • Alfalfa tends to have a relatively high DCAD.
  • The importance of DCAD on equine performance is likely to receive further research in the future.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Roberts et al (1999) Exercise Physiology.
  • Harkins J D, Morris G S, Tulley R T, Nelson A G & Kamerling S G (1992) Effect of added dietary fat on racing performance in Thouroughbred horses. J Equine Vet Sci 12 (2), 123.
  • Oldham S L, Potter G D, Evans J W et al (1990) Storage and mobilisation of muscle glycogen in exercising horses fed a fat supplemented diet. J Equine Vet Sci 10 (5), 353.
  • Frape D L (1988) Dietary requirements and athletic performance of horses. Equine Vet J 20, 163-172.

Other sources of information

  • Pagan J D (2000) Time of feeding critical for performance. In: Proceedings of the Third Dodson and Horrell Ltd International Conference on Feeding Horses.
  • Carlson G P (1994) Forty years later - can we diagnose and treat anemia yet? In: Proceedings of the 16th Bain-Fallon Memorial Lectures. Australian Equine Veterinary Association (AEVA).
  • Popplewell J C, Topliff D R, Freeman D W et al (1993) The effect of dietary cation-anion balance on acid-base balance and blood parameters in anaerobically exercised horses. In: Proceedings of 13th Equine Nutrition and Physiology Symposium.
  • Hintz H F (1992) Ed. Clinical nutrition. In: The Veterinary Clinics of North America 6 (2).
  • Frape D E (1986) Ed. Equine Nutrition and Feeding. Longman, UK.