Kentucky is in the throes of an early season arctic blast that could cause problems for livestock operations.

A blast of arctic air recently filtered into the lower Ohio Valley, resulting in highs only in the 20s for most Kentucky locations. These temperatures combined with gusty winds causes an extended period of livestock cold stress in the danger and emergency categories. Livestock producers should take precautions and try to understand how these conditions could impact their animals.

Low ambient temperatures can increase horses' energy requirements as they compensate to maintain core body temperature. Horses might need additional food, especially if they are kept outside, said Laurie Lawrence, PhD, University of Kentucky College of Agriculture equine researcher and professor.

"Because a large change in the grain portion of the diet can increase the risk of digestive upset, horse owners should also focus first on increasing the amount and/or quality of the hay that is used," she said. "In general, horses will obtain more calories from alfalfa or alfalfa-grass mix hay than from plain grass hay. If horses have already reached maximum hay consumption, then an increase in grain can be implemented. However, all changes to grain intake should be made gradually."

According to Lawrence, regular body condition scoring is also recommended for horses. Heavy hair coats can often camouflage weight loss in horses, so it is important that horse owners check the amount of fat cover over the ribs and spine regularly, she said. If the boney structures start to feel more prominent, it is an indication the horse is losing weight and that the diet should be changed.

Lawrence offered another tip. "Sorting horses by age, body condition and nutrient requirements makes it easier to feed each group of horses appropriately. Horses are less efficient at digesting low quality hay than cattle, so it is very important to offer them good quality hay in adequate amounts. Under normal conditions adult horses will usually consume 20 to 25 pounds of good quality hay per 1,000 pounds of body weight each day. During cold weather this allocation should be increased by 30-50 percent, depending on the severity of the weather.

"The importance of making sure animals have adequate water cannot be understated," she added. "When water availability decreases, food intake usually decreases as well. So if even if horses have plenty of food available they may not eat enough if their water source is frozen."

According to Jeff Lehmkuhler, MS, PhD, University of Kentucky College of Agriculture beef specialist, the lower critical temperature (LCT) value for cattle is the lowest temperature or windchill at which no additional energy is required to maintain core body temperature.

This same principle applies to horses.

"As the temperature declines below this lower critical value, the maintenance energy value for the animal is increased to maintain core body temperature," Lehmkuhler said. "Animals maintain core body temperature by increasing their metabolism resulting in greater heat production, as well as other heat conservation strategies such as reducing blood flow to the extremities, shivering and increasing intake."

Lehmkuhler explained the hair coat acts as insulation similar to home attic insulation that traps air, enhancing the insulating value. If the hair is wet and full of mud, air is excluded, reducing the insulating value and increasing heat loss from the skin to the environment. The density of the hair coat and its moisture level impacts the windchill temperatures at which cold stress is considered mild, moderate or severe. As little as 0.1 inch of rain can immediately impact cold stress severity by matting the hair down reducing its insulating ability. Acclimation time, hide thickness, fat cover and other factors will also influence the degree of cold stress animals experience.

Similar to cattle, a horse with a thick coat has more insulation, and will lose less heat, than a horse with a thin coat, Lawrence said.

"Another factor that can influence LCT is the size of the animal. Smaller animals have a greater surface area relative to body weight and thus a larger area that can lose heat. Therefore weanling horses may reach their LCT before a mature horse. Horse owners should be aware that cold weather can slow growth because calories are diverted from weight gain to temperature maintenance. To minimize a growth slump during very cold weather, young horses should be given more calories by increasing hay quality and quantity and by providing adequate grain supplementation," Lawrence said.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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