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McLean: water most important winter nutrient

by Wyoming Livestock Roundup

Riverton – According to University of Wyoming Equine Extension Specialist Amy McLean, there are several factors to keep an eye on when looking after horses throughout the winter.
McLean presented her information at the mid-February Fremont County Farm and Ranch Days in Riverton.
First she said several things control the critical temperature of horses during the winter, including hair coat, body condition, wetness, wind chill and shelter availability.
“A wet horse with a short hair coat will have a critical temperature of 60 degrees, while a horse with a moderate hair coat will have a critical temperature of 50 degrees and a heavy hair coat – three inches long – will mean a critical temperature of 30 degrees,” explained McLean. “When the temperature drops below your horse’s critical temperature, think about adding extra energy to the diet.”
As a general rule, she said at 70 degrees a horse will consume two percent of its weight in hay.
“Throw in wind, rain or snow and you may need to feed an additional four to eight pounds of hay,” she said. “With a 10 to 15 mile per hour wind and no shelter, you may need to add 10 to 14 pounds of hay.”
She said knowing each horse’s body condition score going into winter can help detect changes go through the season.
Because a horse’s stomach is only about the size of a basketball, McLean said increased amounts of forage fed for cold weather should be fed in several smaller meals. A horse’s 72-foot small intestine is also a great place for impaction colic without adequate water supplies, she added.
McLean explained there are five main nutrients in a horse’s diet: water, energy, protein, minerals and vitamins.
“Water is number one,” she said, adding that minerals such as phosphorus and calcium are also important, as well as vitamin A – which is provided by beta carotene in green grass or hay – salt, vitamin E and selenium, which is important for foals, stallions and reproductive health. 
“Water is needed for digestion, to move hay through the system,” she continued. “A horse will drink eight to 12 gallons a day.”
She said snow is not a good source of water when feeding hay, as a horse has to eat six times as much snow by volume to equal eight gallons of water.
“It’s important to keep water warm and thawed, and whatever the source of water it needs to be easily accessible and free choice,” she said, noting that horses accustomed to pasturing on open range in the winter, without hay, are less prone to compaction colic and can make do with snow as a source of water.
“The three sources of energy are carbohydrates, fats and proteins,” said McLean. “Fat is a great way to add weight to a horse, as it has three to four times the energy of carbs.”
She said to add vegetable oil or a plant source of fat to the diets of skinny, old or young horses. She also suggests rice bran as a good source of fat, but not protein energy, as it’s more expensive and can overwork the kidneys.
McLean said to pay attention to the total digestible nutrients (TDN) of feed compared to the digestible energy (DE), which is how much the animal can utilize, to get the most bang for your feeding buck.
She recommends feeding .5 percent of the horse’s body weight in grain, and the remaining 1.5 percent in hay, depending on the horse’s activity level and whether or not they’re an easy keeper.
For other winter considerations, McLean said to pay attention to horse shelters and snow and ice accumulation on the roof. “Most roofs can stand 20 pounds per square inch,” she said.
If a horse owner does want to blanket their animal, she said to make sure to do it in layers, with a sheet, medium weight blanket and heavy turnout rug. “Also, check them frequently to make sure they’re not wet underneath,” she added.
In muddy pen conditions, she suggested cleaning hooves daily, and making sure a horse has dry ground to stand on for 12 hours each day to prevent hoof problems.
In case of frostbite, she said it’s common in the ears and around the tailhead of old and young horses.
“You’ll even have the occasional sloughing of hooves,” she noted. “It happens most often in high wind chills when the skin is wet.”
She said frostbite is best treated by applying warm, wet towels to affected areas and standing the horse in buckets of warm water. “Also, sedation and pain medication may be needed during the process, because warming up those areas are going to hurt,” she said.
Christy Hemken is managing editor of the Wyoming Livestock Roundup and can be reached at

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