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Nutrition: reproductive effects

ISSN 2398-2977

Podcast: Nutrition: reproductive effects

Condition of mares and stallions at time of breeding

  • Dietary excess or deficiency may adversely affect reproductive efficiency.
  • Diets grossly deficient in any minerals   Nutrition: minerals  , particularly calcium or phosphorus, is likely to   →   infertility.
  • Mares should be in good body condition at time of breeding - superior reproductive performance has been shown in mares with body fat of 15% or more.
  • Mares that are over or underweight are less likely to conceive than mares in optimum condition.
  • Energy intake is important for ovulation and embryonic development, but less so for fetal growth. Restriction prior to parturition can induce premature birth.
  • Mare with body condition score Body score table of <3.5 in autumn and winter experience longer anestrus. An increasing score promotes cycling.
  • Weight loss is not advisable during reproduction or lactation.
  • Non-pregnant and non-lactating mares should be in rising condition if they are thin or kept in a stable condition if they are heavy and covering is imminent.
  • Thin mares should be fed to gain weight during lactation to maximize fertility.
  • Weight loss in obese barren mares should be timed to occur well before covering is planned so that a rising plane of nutrition can then be implemented.
  • Stallions should be fed enough to maintain good body condition which will depend on the amount of time spent in paddocks or in stalls and the number of mares serviced - usually require 125% of maintenance.
  • Stallions that are over or underweight may have reduced libido.
  • Overweight stallions can be given a low energy balancer or supplement to provide a balanced diet and promote good fertility.
  • See also nutrition for brood mares   Nutrition: brood mare  .

Daily requirements for 500 kg horse

Maintenance, mature horse
  • Digestible energy - 69 MJ.

Pregnant mare

  • 0-9 months: Digestible energy - 69 MJ.
  • Last 90 days: Digestible energy - 80 MJ.

Breeding stallion

  • Digestible energy - 88 MJ.

Non-breeding stallion

  • Digestible energy - 69 MJ.

Environmental factors

  • Natural season for breeding activity occurs from April to October in the British Isles and is dependent on day length.
  • Mare and stallion fertility is greatest in the summer.
  • Breeding can be induced earlier, eg December and January in northern hemisphere, by manipulationg light duration and diet or influencing hormonal cycles.
  • Foal heat occurs within 14 days of foaling and thereafter at 22 day intervals.
  • If mares are thin during lactation, they should be fed well to maximize their fertility and maximize the pregnancy rate at 90 days post-foaling.

Print off the Owner factsheet on Nutrition - keeping your horse on top form to give to your clients.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hintz H F (1992) Clinical nutrition. Vet Clin North Am 6, (2).

Other sources of information

  • Frape D (2004) Equine Nutrition and Feeding. 3rd edn. Blackwell Publishing Ltd, UK. ISBN: 1405105984.