Winter Management and Nutrition for Dairy Cattle

 By Heather Smith Thomas

 Richard Norell, University of Idaho Professor and Dairy Specialist (Idaho Falls Research and Extension Center) says cattle must maintain a core body temperature of about 101ºF. “During winter months, the need for cattle to maintain their core body temperature can become a challenge,” he says.

Cold stress occurs when body temperature drops--when metabolic processes are not enough to keep cattle warm.  “A cow with dry winter coat can withstand temperatures below 18ºF before feeling cold stress.  She seeks shelter to avoid wind and cold and eats more feed. With good body condition, a dry coat, shelter, fresh water and good nutrition, dairy cattle can tolerate temperatures well below zero,” says Norell.

Cattle have three processes that help prepare them for winter: growing winter hair, adding fat beneath the skin for insulation, and increasing metabolic rate.  “Cattle exposed to cool fall weather grow thick coats to provide insulation.  A thick hair coat reduces heat loss if it stays dry and clean,” he says.  If there’s much wind, or hair is wet, heat losses increases.
Monitoring body condition as cattle go into winter, and feeding to maintain proper condition is important for minimizing cold stress. “Metabolic rate adjusts to help produce more heat to help maintain core body temperature.  However, takes nutrient resources away from other body functions such as milk production if a higher energy diet is not provided,” says Norell.
FEED AND WATER – In cold weather, cattle need more calories to keep warm.  “A USDA study found that maintenance energy requirements for lactating cows increase by 50% when temperature falls from freezing to zero degrees.  Increase in energy requirements are greater with thin cattle, wet hair, or exposure to wind,” says Norell.
“Discuss with your nutritionist the ideal feeding options for your own herd and facilities.  Consider sorting out thin cows or heifers so you can provide more specialized care such as a higher-energy ration and less crowded shelter.”
“Cows should have access to the feed bunk at least 21 to 22 hours per day (spending no more than 1 hour per milking period in the holding pen).  Minimizing time away from the feeding area allows optimum intake.  This is especially important for fresh, early lactation, and high-producing cows,” he says.
The art of feeding cows is getting the right feeds, to the right cows, at the right time, and in the correct physical form.  “Cows should be fed a consistent ration at a consistent time each day.  A careful feeder who accurately prepares total mixed rations (TMR) contributes greatly to the performance of a dairy herd,” says Norell.
“Feed bunks should be monitored daily and the amount fed to the group adjusted as necessary.  Some producers check feed bunks once a day and strive to minimize the amount of leftover feed in the bunk to 1 to 2% of the total feed offered.  Others strive for a wet slick bunk (feed just cleaned up, bunk wet) or dry slick (feed gone, bunk dry).  Feed intakes increase during cold nights; more ration should be offered to make sure cows are full-fed.  An empty bunk for several hours before the next feeding can result in lower milk production,” he explains.
“Monitor the feed bunk more frequently to ensure bunks are not empty too long.  Uneaten ration should be removed each day.  Ration wet with rain or snow won’t be readily consumed.”  A roof over the feed bunk ensures optimum consumption.
Check sources regularly to make sure cattle can drink and are drinking enough.  “Frozen water or excessively cold water significantly reduces water and feed intake.  Cows can drink 3 to 5 gallons per minute, so the water supply needs to keep up with demand.  Cows prefer water between 40 and 65ºF.  If it gets much below 40 degrees they won’t drink enough,” he says.  Use a thermometer to determine if tank heaters and waterer heating elements are in proper working order.
LACTATING DAIRY COWS – Rations for lactating cows in winter are formulated to meet body maintenance requirements (including keeping the animal warm) plus milk production, weight gain, and reproduction.  “Energy intake is used first for body maintenance and our goal is to keep maintenance requirements as low as practical by providing shelter and bedding to keep hair clean and dry and providing wind protection.  Wind and wet hair increase maintenance requirements,” explains Norell.  
In cold weather, feed more total calories.  “Looking at percentage of the energy needs for a lactating cow producing 60 pounds of milk, her maintenance requirement accounts for about 36% of total energy at 32 degrees and 46% of that total at zero.  Cows increase feed intake as temperature drops; the increase in energy intake will cover most if not all the increase in maintenance,” he says.
Modern dairy rations are high in energy, for high production. “Dairy producers try to produce or buy high-quality forages for lactating cows and purchase cost-effective supplemental feeds to meet specific needs of high-producing cows.  Rations are formulated to meet specific nutritional targets for various production groups within the herd.  Monitor feed intakes, and increase ration amounts to adjust for periods of extreme cold.  Feeds are not changed for colder weather (high quality feeds are already used); the amounts are simply increased,” he explains.
HEIFERS, DRY COWS AND CALVES - Heifers and dry cows are fed diets that are 80 to 100% forages and typically receive lower quality, less-expensive hays and corn silage.  “No changes are made in diet except in extended periods of cold, at which time a couple pounds of grain may be added,” says Norell.  
“Bottle-fed calves are the most susceptible to cold stress.  Calves should receive at least 6 quarts of milk daily in winter, and have calf starter available daily.  They also need deep bedding (dry straw) to keep warm.  The hutch should be up on a gravel base so melting snow flows away from it.  The opening should not face into prevailing wind--to prevent drafts in the hutch and wet bedding from blowing snow,” he says.

Herd Health
“Cows with previous health issues and bottle fed-calves are the groups most susceptible to cold weather.  Chapped and frostbitten teats are a potential risk during cold and windy conditions.  Teats must be dry when cows leave the parlor during cold windy conditions--or use a winter teat-dip formulation.  Ears of calves may be frostbitten if suckled by other calves,” says Norell.
Prevent accumulation of ice on walking surfaces. Consider roughing up the surface and adding sand or gravel for traction.  Livestock are hardy, and with a little help can easily make it through short periods of cold stress, but when cold temperatures are sustained for long periods, special attention will be needed.