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COLD
WEATHER NUTRITIONAL STRESS IN HORSES
By Donald Stotts
It's a lesson in thermodynamics: Humans combat cold weather by
putting on additional clothing; horses fight the elements by
using more energy to maintain body temperature. But while most people can address their own needs, horses are
dependent upon their owners to provide proper nutrition and
protection from the weather, said Dave Freeman, Oklahoma State University Cooperative Extension equine specialist.
"The
temperature below which a particular horse starts to expend
additional energy for maintaining body warmth (critical
temperature) will vary because of fat cover, hair thickness, acclimatization of the horse to cold, hair-coat wetness and
wind-chill," Freeman said.
For example, a
horse with short hair, exposed to wet, cold weather, may need
significantly more energy when the temperature gets below 50
degrees Fahrenheit. A horse acclimatized to cold weather, with a thick hair coat and fat cover, may not
expend appreciably more energy until the temperature drops
below 30 degrees Fahrenheit. As a general rule, a one
percent increase in the energy requirements is needed to
replace energy loss from the cold weather for each degree the
temperature falls below the horse's thermo-neutral zone (lower
critical temperature).
In other words,
a horse manager would have to supply roughly two pounds more
feed for each 10 degrees Fahrenheit below the critical
temperature per day when horses are consuming typical hay and
grain rations, a situation that is not practical.
"That's why horses need to be preconditioned for cold
weather by increasing fat thickness and body condition before
the onset of winter," Freeman said. In addition,
Freeman said it is important to remember that a horse manager
can't just provide additional feed to offset loss of body
condition.
"Sudden
changes in grain composition and amounts will increase the
incidence of colic and founder," he said. "It's best
to make adjustments in grain gradually over a period of
several days, especially if horses already are consuming large
quantities of grain. " Horse managers also should
consider feeding large amounts of grass hay to horses
restricted from forage. Free-choice hay helps horses exposed
to cold weather, partly because of the heat generated by
digestion and also as an aid to a continual, safe supply of
nutrients.
A concern with
providing free access to hay is maintaining a fresh hay supply
in ways which reduce hay waste. Large hay losses usually occur
when round bales are placed on the ground in pens of horses. "Those who have elevated
hay feeders large enough to hold round-bales need to use
them," Freeman said. "No matter the method, hay exposed to wet
weather for any length of time generally will require removal
because of decreased palatability and potential problems
resulting from horses ingesting moldy hay."
Freeman said
another way horse owners can lessen an equine's stress
resulting from exposure to cold weather is to provide some
form of shelter from wind, rain and cold. Some pastures provide enough natural protection that man-made
shelters are not required. "Owners housing horses
in areas unprotected from wet, windy weather should consider
constructing windbreaks or sheds," he said. "The
cost of windbreaks and sheds will be partially offset by
savings in feed costs as a horse's energy requirements
lessen."
Owners also need
to consider horse instincts and herd pecking orders when
deciding on windbreak or shed design. Those areas housing one
or two horses that are compatible with one another will allow
for an enclosed shed with three or four sides. These
structures should be similar in size to recommendations for
stalls, a 10-feet by 10-feet minimum for one horse.
The same type of
structure will not work in pens with large numbers of horses
or bands of horses with large ranges in horse dominance
orders. "An enclosed, sided structure may increase horse
injury to horses on the low end of the herd dominance order by
the more dominant horses," Freeman said. "This type
of structure may be inefficient because dominant horses will
keep others from having access."
Freeman
recommends single-sided windbreaks with a top cover be used in
herds with a dominance problem. Also owners should consider
two or three of these structures spread about the area because
one long, continuous structure is easily guarded by dominant
horses. Structure dimensions will depend on the degree
of herd dominance problems.
In situations
where aggressive behavior becomes such a problem that horses
need to be separated, Freeman said horses on the low end of
the herd order generally will need more shelter because they
are the ones that are usually in the least favorable body
condition.
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