Management and Feeding
in Cold Weather
Table of Contents:
- Thermoregulation in Cold Weather
- Management of Horses in Cold Weather
- Guidelines for Feeding Horses During Cold
The February "miracle" of the Edmonton toddler who "froze"
outdoors in sub-zero temperatures and lived is a solemn reminder
of the danger cold weather poses for homeotherms (warm-blooded animals).
Cold weather generally does not affect horses as suddenly or dramatically,
if at all, as was seen with this infant.
Although horses are very adaptable to cold weather, they must be
managed sensibly during winter. A basic review of energy (heat)
exchange in the horse will help to explain why certain management
practices are necessary during cold weather. The easiest way to
understand the impact of cold weather on a horse is based on the
heat (energy) balance equation. Heat or energy balance is the difference
between heat loss and heat gain over time. If heat gain exceeds
heat loss over time, the horse will gain weight. If heat loss exceeds
heat gain, the horse will lose weight. The most important loss of
heat in cold weather is to the environment. Warm objects lose heat
to the environment whenever air temperature is colder than the object.
Horses, whose skin temperature is about 30oC, will lose heat to
the air around them whenever the air temperature is below 30oC.
The colder the air around the horse, the greater the heat loss will
be. The main source of heat gain is the energy (calories which convert
to heat) obtained from feed. Other minor sources of heat gain are
muscular activity, the sun and mechanical heat in barns.
Thermoregulation in Cold Weather
Horses respond in two ways to cold: acutely (immediately) and chronically
(adaptive or acclimatization). The immediate response of a horse
to a sudden change in temperature is to change its behaviour. Horses
will seek shelter from the cold and wind, or huddle together, to
decrease heat loss. Horses stop foraging and stop moving to conserve
energy. Horses in cold, windy conditions typically stand with their
heads away from the wind, their tails set low and into the wind.
Shivering and other voluntary muscular activity can generate substantial
body heat. It is not unusual to see horses running in cold weather.
The muscular contraction involved in physical activity, such as
running, results in heat production. In the dissipation of this
heat, the horse's inner body core (heart, liver, intestine, etc.)
is warmed. Thyroid hormone secretion is increased during sudden
cold exposure in adult horses, but this response is short-lived.
Horses will also vasoconstrict (reduce) blood flow to the extremities,
such as the lower legs, the ears and the muzzle, and their hair
will stand up (piloerection) to effectively increase the haircoat
Horses exposed to constant chronic cold weather acclimatise to
the cold. Typically, horses require 10 21 days to adapt to
cold. For example, a horse kept at 20°C and exposed to temperatures
of 5°C will adapt to temperatures of 5°C over 10 to 21 days.
When the temperature drops to 5°C, the horse will need
another 10 21 days to adapt to this increasing cold. This
process continues up to 15°C, which is the lower critical
temperature (LCT). Once the LCT is reached, physiological changes
and human intervention, such as shelter and/or extra feed, are needed
to help the horse cope with the cold. One of the physiological changes
is an increase in density and length of the horse's coat. Body temperature
and respiratory rates decrease to conserve heat/energy. The temperature
of the lower legs, ears and muzzle decrease because blood is shunted
from the extremities to reduce surface heat loss.
The horse's ability to adapt to cold depends on the duration of
the cold weather and on the horse's energy intake. The latter factor,
energy intake, is the most critical in determining how readily a
horse develops a tolerance for cold. Horses lose weight if they
do not eat enough energy to offset the heat loss to the cold surrounding
air. Enough feed and good-quality feed are needed to supply adequate
energy intake for the horse. Fat horses are able to mobilise some
of their fat deposits as energy during cold snaps but enough good
feed is the main solution for keeping horses in good condition through
winter. Well-fed horses adapt without problem to cold weather, whereas
unfed horses lose weight and lose cold tolerance. Yearling horses
fed a high quality diet free-choice are able to tolerate temperatures
as low as -11°C with no ill effect. Horses will generally eat
to meet their energy requirements. In cold weather, feeding good
quality hay free-choice is the simplest way to ensure that the horse
will meet its energy requirements.
Management of Horses in Cold Weather
Various factors affect the ability of a horse to withstand cold.
Large bodied horses, e.g. draft horses, are much more able to withstand
cold because of a lower relative body surface area per unit of weight
(area:weight ratio). Belgians are more cold tolerant than Thoroughbreds.
Newborn foals have very poor cold tolerance. Horses up to one year
of age are less cold tolerant than adult horses. In late pregnancy
(9th month and beyond), energy requirements of mares increase and,
consequently, cold tolerance decreases. However, a winter-adapted,
well-fed, pregnant mare is at no higher risk than a gelding. Poor
teeth, parasites and disease also decrease the cold tolerance of
Horses kept in a shelter (shed) can conserve up to 20% more body
heat than horses kept in an exposed area. A three-sided shed is
suitable protection from cold winds and snow. A typical shed should
be 8 metres deep and should provide an area of 7.5 - 9 m2 per horse
for lying down. Adequate bedding, preferably straw, should be provided
in sheds, especially for young horses. Well-bedded bluffs, coulees
and treed areas can serve as alternatives for sheds. Animals that
are able to lie down can reduce surface area heat loss by 20
Dietary energy is the only nutrient that must be increased for
horses kept at temperatures below their LCT. The LCT for growing
and adult horses in Canada is 0°C and -15°C, respectively.
Maintenance energy intakes of adult horses must be increased 2.5%
per Celsius degree below temperatures of 15°C or the equivalent
of 2% more feed. Feeding good quality hay is the easiest and most
suitable way to supply additional energy for idle, adult horses
kept outdoors in cold weather. Horses will increase their voluntary
feed intake if permitted. Horses can be fed hay free-choice without
fear of producing laminitis (founder). However, owners who are limit-feeding
their horses should ensure that 2% more feed per degree below -15°C
is available to their horses. Groups of horses housed outdoors should
be fed in a way that reduces competition among horses. Grouped horses
typically have a pecking order for feed and space. Often, timid
horses will become thin, even if plenty of feed is available, because
the dominant horses in the group won't allow them to eat. Any type
of feeder, including feeding on top of clean snowy areas, can be
used, as long as enough individual feeding space (3 15 metres
between horses) is available for the horses in the group. Feeders
are preferable since they will reduce feed wastage by 25%. This
is especially true of those with a floor in them. Salt and mineral
should also be provided. Clean fresh water should always be available
to horses. Snow is an unsuitable substitute. A horse would have
to consume ten times its water requirement in snow to meet its needs.
The horse would then need to use energy to raise the temperature
of the snow from the outside ambient temperature to the horse's
body temperature of 37° C. This is a huge energy drain and,
when coupled with poorly digestible hay, can lead to gut impaction.
Winter pastures should not be relied upon to provide the sole source
of nutrients for horses since they are usually poor feed sources
for overwintered horses. Not only is the nutrient quality poor but,
in deep snow, the maintenance energy needs of horses can increase
by 40% because the horses have to crater or paw through the snow
to find low quality feed.
The cost of weight loss in the horse is much higher than most people
realise. Thin, malnourished stallions lose their ability to produce
sperm. Thin mares have a very low conception rate. Underfed weanlings
can become permanently stunted. Finally, the extra cost of feed
needed to rehabilitate a thin horse back to normal will equal or
exceed the cost of the feed that should have been given to the horse
to maintain its body weight. Feeding horses is costly; not feeding
horses is more costly.
Guidelines for Feeding Horses During
- The easiest method of feeding horses in cold weather is the
simplest: feed high quality forages free-choice. Most horses will
eat 2 to 2.5% of their body weight in hay per day. Average daily
free-choice intakes of hay by a 600 kg (1320 lb) horse is 12
15 kg (26 33 lbs)/day or about a half of a 65-lb square
bale per horse per day.
- If you are limit-feeding horses outdoors, adult horses being
fed at maintenance will need an additional 2% more feed per degree
below the lower critical temperature (-15°C). At 40°C,
the horse will need 4.5 5 kg (10 - 12 lbs) more than it
ate at temperatures above 15°C.
- Use highly digestible hays and supply a sufficient quantity
of hay. Coarse overmature hays are low in energy and high in indigestible
fibre. In cold weather, when energy demands are high, overmature
hays will not supply sufficient energy and, furthermore, if fed
without sufficient water, can cause impactions. Alternatively,
grain can be added to the diet. Caution must be used when adding
grain to the diets of horses unaccustomed to grain because founder
(laminitis) can occur. All horses fed grain should be gradually
adapted to small amounts of grain over a period of 7-10 days.
- Supplemental vitamins A, D and E may be needed. Appropriate
mineral-vitamin mixes should be chosen. A fortified 2:1 calcium-phosphorus
mixture is recommended for feeding with grass hays and a 1:1 Ca-P
mixture is recommended for feeding with alfalfa hay.
- Provide adequate heated (2-10°C) water, if possible. Water
helps maintain appetite and digestive function. Snow is not a
- If available, a well-bedded, south or east-facing shed is useful
for young and old horses. Alternatively, provide protection from
the wind by providing bedding areas behind snow fences, in coulees
or bluffs, or among trees. Horses that can lie down will conserve