A period of rest and recuperation is almost inevitable during a horse or pony’s career, irrespective of whether we are discussing a top-flight performance horse, or simply a hard-working pony club pony.
Horses and ponies may require a period of recuperation that includes complete box rest for a variety of reasons, for example surgery following an orthopaedic issue or colic, or due to systemic disease or viral challenge. Laminitis is another common reason for a prolonged period of box rest, especially in ponies.
Rest and recuperation poses a particular nutritional challenge and some major changes to the diet may be required during the period of box rest, but also once the horse or pony is brought back into work.
The focus of the diet for a horse or pony on box rest as well as those that are being re-introduced back into exercise training should be: n to provide an adequate but not excessive intake of energy; n to provide a suitable profile of macro and micronutrients to support tissue repair, digestive function, muscle function, immunity and respiratory health; n to maintain overall condition and limit muscle wastage; and n to minimise behavioural problems associated with box rest and a general lack of activity.
Energy or caloric intake in boxrested horses, as well as those coming back into work, is significantly reduced in comparison to that of horses in full work. However, care should be taken to account for the potential increased energy demands of severe trauma or stress in recuperating horses. There are no specific figures regarding this in horses, but in human patients with major fractures, basal energy requirement is reported to be increased by 20-25% (Jensen et al., 1982).
Forage is multifunctional for recuperation
Adequate forage intake is probably the most important aspect of a ration for rest and recuperation and when the level of exercise increases in those horses being reintroduced to exercise training.
Multiple forms of good quality hay or haylage that has a low mould burden is essential to help maintain both digestive and respiratory function, but also to effectively satisfy the need for occupational therapy (Goodwin et al., 2007). The prevalence of stereotypic behaviours such as windsucking and wood chewing is higher in horses that are fed inadequate amounts of forage coupled with low fibre high starch concentrate feeds (Nicol, 1999).
During this period, horses will also benefit from a shift in the main source of energy away from high starch containing cereals, which can contribute to excitability and stereotypic behaviour, towards feeds with a higher digestible fibre content.
Oil can also be used to supplement the ration if energy requirements demand. This is particularly relevant for horses or ponies that are at risk from equine rhabdomyolysis, where box rest and a high starch diet is a risky combination (Valberg and McKenzie, 2005).
Harnessing the anti-inflammatory potential of fatty acids
There is evidence to suggest that an increased omega 3:6 fatty acid ratio in the diet is beneficial during rest and recovery from injury or disease in horses (Manhart et al., 2009; Woodward et al., 2007). Whilst inflammation is a functional component of the repair process, it needs to be carefully managed.
Stabled horses usually have a higher intake of omega 6 fatty acids, which in comparison to their omega 3 counterparts are characteristically proinflammatory. Omega 3 fatty acids, which can be found in grass, linseed meal, tuna oil and some algae, give rise to a number of anti-inflammatory mediators such as prostaglandins and cytokines. However, the omega 6 fatty acid ã-linolenic acid (GLA), of which the algae Spirulina is a rich source, is also reputed to exhibit antiinflammatory effects (Collaa et al., 2004).
Strategies to maximise pre-caecal digestion are beneficial
Concentrate feeds should be kept small and fed on a little and often basis to maximise the digestion of both starch and protein pre-caecally. This will limit the detrimental effect of starch reaching the hindgut on the microbial balance. As horses can only utilise amino acids absorbed in the small intestine, high pre-caecal protein digestibility is vital.
As the intake of concentrate feed is likely to be relatively low, it must have a higher micronutrient density than a feed designed for maintenance or low work. Most traditional coarse mixes and cubes require a daily intake of about 500g per 100kg bodyweight to ensure adequate provision of micronutrients and so the use of a broad-spectrum vitamin and mineral supplement, or a feed balancer product should additionally be considered.
Adequate provision of antioxidant micronutrients and vitamins such as selenium, vitamin C and vitamin E is essential to support immune function and to curb the deleterious effects of free radicals that are synonymous with inflammation.
Protein intake must promote quality and not just quantity
Repair of tissue is associated with an increased rate of cellular turnover and therefore an increased requirement for amino acids from dietary protein.
During recovery from injury or disease, protein quality and pre-caecal digestibility should ideally be high, particularly where the functionality of the small intestine is compromised due to surgical resection following colic. However, the protein quality and digestibility offered by many low energy feeds, which are traditionally used for horses during rest and recuperation, may be inadequate to optimally support this process.
In addition, the pre-caecal digestibility of protein from forage is generally low and so in order to provide an optimum balance of amino acids to support the repair process as well as muscle protein turnover, provision must be made through the concentrate feed.
Feed ingredients such as soya and whey have traditionally been fed, but new ingredients such as the blue green algae Spirulina also provide a rich source of quality protein with high pre-caecal digestibility.
Key amino acids involved in repair processes
There are a number of amino acids, e.g. arginine, ornithine, glutamine and leucine, that are reported to have a beneficial effect on recovery processes in athletes (Pasquale, 2008) and which are therefore of relevance to sports injury and disease in horses.
Arginine, an amino acid reputed to function in a number of ways to speed repair from injury:
- promotes insulin release and IGF action – these are anabolic hormones that stimulate protein synthesis and collagen deposition;
- stimulates nitric oxide production, which increases blood flow to affected areas and activates macrophages involved in tissue clean up;
- promotes the conversion of ornithine to proline required for collagen synthesis.
Ornithine is the major metabolite of argenine that is reputed to promote wound healing.
Glutamine is an amino acid that is essential for the metabolism of rapidly turning over cells, such as lymphocytes and enterocytes. Not surprisingly, therefore, the requirement for glutamine increases in situations of trauma or sepsis. In horses, plasma glutamine is reduced following viral challenge (Routledge et al., 1999) and glutamine status can be improved through supplementation of the diet with glutamine-rich feed ingredients (Harris et al., 2006).
Leucine is a branch chain amino acid that is reputed to limit muscle wastage that occurs during prolonged periods of inactivity by retaining the normal rate of protein synthesis.
In summary, horses that are undergoing a period of rest and recuperation, or that are being reintroduced back into work, will benefit from a high intake of forage, coupled with a low starch and high fibre concentrate feed with an enhanced micro nutrient content.
In addition, supplementary feeds that offer a superior source of protein of high quality and digestibility to improve targeted amino acid delivery may also be beneficial.
References
Collaa, L. M., Bertolina, T.E. and Costab, J. A. V. (2004) Fatty acids profile of Spirulina platensis grown under different temperatures and nitrogen concentrations. Z.Naturforsch 59C: 55-59.
Goodwin, D., Davidson, H. P. B. and Harris, P. (2007) Responses of horses offered a choice between stables containing single or multiple forages. Veterinary Record 160: 548-551.
Harris, R. C., Harris, P. A., Routledge, N. B., Naylor, J. R. and Wilson, A. M. (2006) Plasma glutamine concentrations in the horse following feeding and oral glutamine supplementation. Equine Veterinary Journal Supplement: 637-642.
Jensen, J. E., Jensen, T. G., Smith, T. K., Johnston, D. A. and Dudrick, S. J. (1982) Nutrition in orthopaedic surgery. Journal of Joint and Bone Surgery 64: 1,263-1,272.
Manhart, D. R., Scott, B. D., Gibbs, P. G., Coverdale, J. A., Eller, E. M., Honnas, C. M. and Hood, D. M. (2009) Markers of Inflammation in Arthritic Horses Fed Omega-3 Fatty Acids. The Professional Animal Scientist 25: 155-160.
Nicol, C. (1999) Understanding equine stereotypies. Equine Veterinary Journal Supplement 30: 20-25.
Pasquale, M. G. D. (2008) Amino acids and proteins for the athlete: the anabolic edge: CRC Press, Boca Raton, Florida.
Routledge, N. B., Harris, R. C., Harris, P. A., Naylor, J. R. and Roberts, C. A. (1999) Plasma glutamine status in the equine at rest, during exercise and following viral challenge. Equine Veterinary Journal Supplement 30: 612-616.
Valberg, S. and McKenzie E. C. (2005) Muscle disorders: untying the knots through nutrition. In: Pagan, J. D. (ed.) Advances in Equine Nutrition III. Nottingham University Press, Nottingham. pp473-488.
Woodward, A. D., Nielsen, B. D., O’Connor, C. I., Skelly, C. D., Webel, S. K. and Orth, M. W. (2007) Supplementation of dietary longchain polyunsaturated omega-3 fatty acids high in docosahexaenoic acid (DHA) increases plasma DHA concentration and may increase trot stride lengths in horses. Equine and Comparative Exercise Physiology 4: 71-78
