Thermoregulation In Horses During Winter.

Thermoregulation is the term given to describe the way in which horses control their internal temperature. The horse’s hair, fat, skin and blood vessels play a major role in the horse’s thermoregulation, with hair and fat creating a layer of insulation and the skin and blood vessels restricting heat loss around the body.

The horse’s ‘normal’ status is referred to as their thermoneutral zone (TNZ) and it is within this zone that the horse can regulate its body temperature with very little loss in energy. As every horse is different, their ‘TNZ’ will differ considerably based on the temperature that the horse is acclimatised to. Factors affecting the TNZ will also include the horses age, breed, body condition, medical conditions and of course whether the horse has been clipped of its winter coat.

Once temperatures begin to drop during the winter months, the horse’s energy requirement increases in order to maintain the horse’s body temperature and reduce the effects of heat loss. For horses kept in milder climates, this is typically as temperatures begin to drop below 5℃, whereas this could be as low as -15℃ for horses who are well acclimatised to northern regions.

Maintaining the horses body temperature can be achieved in many cases through the sufficient supply of forage. The fermentation of forage produces heat, acting as an internal radiator to keep the horse warm. Ensuring that your horse receives no less than 1.5-2% of their body weight in forage per day is crucial in maintaining their overall digestive health, as well as contributing to the maintenance of a healthy body condition. For horses who struggle to maintain their weight, increasing hay provisions or providing alternative fibre buckets for those with limited appetites is recommended.

The impact of rugging

Rugging of horses is a long-established practise that is done in order to provide additional protection to the elements and to help keep the horse clean. However, research has looked into the effect of rugging on thermoregulation, and how this might also affect feed intakes. Horses were split into groups with and without rugs and were offered free access to round bales of hay whilst being kept on dry lots. The horses who were rugged ate an average of 2.3% of their body weight per day, whilst horses who were not wearing a rug ate approximately 2.5% of their body weight per day. The rugged horses also demonstrated a weight gain of approximately 7.3kg throughout the study period, whereas there was no weight gain within the unrugged group. This suggests that the unrugged horses consumed more forage in order to conserve energy (calories).

In conclusion, the energy demands of the horse during the winter months will need to be considered on an individual basis. For horses who are prone to gaining weight in the spring and summer months, encouraging the healthy expenditure of energy (calories) through the process of thermoregulation can be of great benefit in minimising excess weight gain in milder temperatures. For youngstock, older horses or whose who may have been clipped, providing an increase in forage and rugging can reduce the amount of energy lost through thermoregulation. If required, the use of a high calorie concentrate feed will provide additional calories in those who struggle to maintain their weight on fibre alone.

Need more guidance?

For advice on how to increase your horses fibre intake, check out our 'Increasing Fibre Intake' factsheet here.

Alternatively, contact our nutrition team on 01622 718487 or via nutrition@saracenhorsefeeds.co.uk for a personalised feeding plan for your horse or pony.