Winter Care for Dairy Calves.

 By Heather Smith Thomas.

Dairy calves need extra care in winter.  Dr. Pete Erickson, Extension Dairy Specialist, University of New Hampshire, says the most important thing for any calf is to get colostrum as soon as possible.

Importance Of Colostrum
“We mainly think in terms of immunity, but the other important ingredient in colostrum (besides fluid) is fat,” he says.  This is especially important in cold weather, to give the calf energy/calories to keep warm.

“Baby calves have a lower critical temperature of about 55 degrees.  Below that, they become chilled and stressed.  Dairy calves are less hardy than beef calves and need more attention in cold weather.  A newborn calf has only about 18 hours of internal fat stores.  It is important to get colostrum into that calf soon,” Erickson says

“We need to get the calf dried off and warm.  Many dairies have calf warmers—a box with a heat lamp.  We dry the calf, dip the navel—everything you’d normally do regardless of the time of year—but the more colostrum you give, the better.  Data from Switzerland indicates that the more colostrum we give a calf, the better she will perform later.  We need to provide at least a gallon. 

Some people give it all at once, some give 2/3 at birth and 1/3 a little later, but our data says the gallon needs to be provided before the calf is 12 hours old,” says Erickson.  Gut closure begins immediately after birth.  It’s a race against time, and it’s also a race between the antibodies in the colostrum and the pathogens the calf encounters.  It’s crucial to get the optimum amount of colostrum into the calf as soon as possible.

This is especially important if there’s stress, since stress hastens gut closure.  Calves may be unable to absorb enough antibodies if they are already cold and stressed by the time they get the colostrum.  A difficult birth is also a stress.  The calf needs colostrum immediately, to supply crucial antibodies and fat reserves.

“Ideally, colostrum should be tested with a colostrometer or refractometer.  The fat content of colostrum varies.  I’ve seen low fat content in Holsteins of 4.5 and up to around 7% or a little more.”  The fat and antibody levels are a bit lower in Holsteins just because of the large volume of fluid.

“The colored breeds have better quality colostrum from an IgG standpoint and fat standpoint (less total volume, and more concentrated solids) but sometimes we run into problems, especially with Jerseys, since they often don’t produce much colostrum in the winter,” says Erickson.

“We are doing a research study here, evaluating this issue.  My first experience with this problem was with a 250-cow Jersey herd in Maine.  The dairy wasn’t sure what was happening; some people thought it was genetic, or diet (they’d just put in new corn silage).  An interesting study was done at the veterinary school at Washington State University.  They looked at colostrum production in Jerseys throughout the year, and found it varied with the seasons.  During winter, the cows produced less colostrum.  In December, 48% of those cows produced zero colostrum.  Those researchers think it has to do with photoperiod and less daylight,” he says.

“Here in New Hampshire we are halfway between the equator and the North Pole, so the days are fairly short during December.  We have two dairy herds at UNH and our Jersey herd stops producing colostrum about November.  The problem is that it’s an organic herd, and up until this past year there was no organic colostrum replacer on the market.  So we bank frozen colostrum, for use in winter,” says Erickson.

“Now Saskatoon Colostrum, which is a great company in Saskatchewan, has an organic colostrum that just came out on the market.  It’s very expensive, but now available for organic dairies,” he says.

Shelter
Weather and temperatures vary from region to region, but calves need a dry environment and windbreak.  Dr. Bob James, a dairy consultant with GPS Dairy Consultants and owner of Down Home Heifer Solutions, Blacksburg, VA (Former Extension Scientist at Virginia Tech) specializes in calf health and nutrition, and works with many dairies across the country.  He says he doesn’t worry so much about keeping calf shelters warm, since that’s not cost effective in all climates, but we can use deep-bedded straw and dry housing.  “For young calves, for their first month or two we may use calf jackets, to help retain body heat and reduce maintenance requirements,” says James.  They have to stay dry, because if their hair coat gets wet, it loses its insulating quality, and they get chilled.

Air quality also needs to be good; there must be good ventilation—so the air they are breathing is not dusty, laden with ammonia or pathogens.  “Most calf facilities are too closed up (to try to keep the calves warm) so we get into issues with poor air quality and respiratory problems.  We need good ventilation year-round,” he says.

“One of the benefits of working all across the U.S. is that I see a wide variety of climates.  What works in Wisconsin doesn’t work in Florida or Arizona, so we have to tailor our recommendations for each situation,” says James.

Many dairies utilize calf hutches and some use calf barns.  Erickson prefers to keep calves individually housed, but the important thing is adequate shelter.  “One of the benefits that Midwestern and Western regions have is access to a lot of straw.  We don’t have many grain fields in New England but we do have a lot of trees, so people often use sawdust or shavings.”  Straw makes a better insulating bed for calves, however.

“The rule of thumb when bedding hutches with straw is to have it deep enough that the calf can make a nest, nestling down into it.  It needs to be deep enough that you can’t see the calf’s legs,” says Erickson.

“The benefit of a calf hutch is how it can retain heat on a cold winter day, and this depends on how you face it in regards to the sun.  You want the morning sun shining in, so you face it south/southeast.  If the calf is in the back of a nice calf hutch, it can actually stay fairly warm,” he says.  

Don’t face hutches toward prevailing wind.  “One problem here is that a lot of our dairies are in valleys.  The wind comes straight up or down the valley, and our valleys tend to run north and south.  People have to be creative in location of calf hutches, keeping prevailing winds in mind,” he says.

Bedding must be clean and dry.  It can’t be new bedding on top of wet bedding,” he explains.  “Here at the university, students clean the calf hutches every day.  They need cleaned out—at minimum—a couple times a week.”

Location of calves in relation to the cows is also important, regarding wind direction.  “I don’t want calves downwind from cows.  Cows have much better immunity.  If there is a ‘bug’ running through the cow barn and calves are downwind from the cows, some pathogens can be aerosolized and carried on the wind.  Then the calves may get sick.  Calves, on the other hand, can be upwind from the cow barn, and the cows won’t get sick from wind bringing pathogens from the calves,” Erickson explains.

Diet
Some dairies feed milk but most of them use milk replacer.  There are many milk replacers on the market.  “There’s the standard 20% protein, 20% fat, and some with 26 to 28% protein.  I’ve seen some with as high as 32% protein.  There are also a lot of ways to feed milk replacer to calves.  In the warmer months we generally feed milk replacer twice a day.  In winter it’s important to feed three times a day,” says Erickson.  In cold weather the calves need more groceries, more often, to help generate body heat in addition to maintenance/growth requirements.

James says the old way was to feed calves 2 quarts of milk replacer in the morning and 2 quarts in the afternoon, using a milk replacer containing 20% protein and 20% fat.  “This barely meets maintenance requirements during moderate weather.  Milk itself (on a powder basis) will vary a bit by breed, but somewhere between 26 and 28% protein and anywhere from 28 to 32% fat.  So we are already cutting back on nutrients to the calf by feeding milk replacer.”  The reasoning was to keep the calf hungry so it will eat more dry feed sooner.

“If we want to optimize lean tissue gain, however, we need to feed something that’s 26 to 28% protein, on a powder basis.  This is expensive.  We do need to meet nutrient requirements, however, and if we look at our cost per pound of gain, it will be cheaper if we do meet their requirements than if we starve them the way we used to.  With the old way, the calf barely had enough to support gain, especially in winter.  And winter in Wisconsin is a lot different than winter in Arizona,” James explains.  In a colder climate, the calf will need even more calories to generate enough body heat.  When looking at the calf’s requirements, we need to define what winter is—and whether it’s cold and damp, or just cold.

Two quarts, twice a day, with 20% protein and 20% fat, is not enough for a calf.  Even if it contains higher levels of protein and fat, it’s not enough.  A Holstein calf, three weeks old, will drink at least 8 quarts a day if allowed to drink all it wants.

“There is a lot of interesting data about fat,” says Erickson.  “It has a lot of value for providing calories.  The other thing we are trying to do when feeding calves, however, is get the rumen developed, so we feed some kind of calf starter.  Energy level is one of the things that dictates what an animal eats.  If you have a very high-calorie diet you don’t have to eat as much.  But we are trying to get calves to eat more solid feed, and if we add too much fat to their milk replacer they might consume less solid feed.  Fat is not fermented; it doesn’t have to go through the rumen to be digested and utilized.  Solids, on the other hand, go to the rumen and are fermented,” he says.

“When something is fermented it produces heat—which helps the calf maintain core temperature on cold days.  Thus we want calves to eat starter and maybe a little hay, to help the rumen develop and start fermenting more feed,” Erickson explains.

“We get the rumen developed by feeding calf starter, and hopefully see more internal core temperature.  I am not saying you shouldn’t feed a high level of fat in the milk replacer; it’s a balancing act, and proportional to how cold the weather is.  If it’s really cold and subzero days, we need to get as much energy into them as we can.”

Calves also need water.  “They need it in the form of water, and not just in milk or milk replacer.  Some research was done by Purina in the mid-1980’s, by a well-known calf researcher, Dr. Al Kertz.  He fed calves the same diet, but half the calves had access to free-choice water and the other half didn’t.  He saw an increase in average daily gain in the calves that had free-choice water, an increase in starter intake, etc.”

Water goes to the rumen, while milk replacer or milk goes to the abomasum (true stomach—where it is digested better than in the rumen) because of the esophageal groove.  Bacteria in the rumen need a watery environment; you can’t shortchange the ruminant on water or digestion is not very efficient.  

“If we are trying to develop the rumen, we need to provide water.  If the calf has starter, some hay, and adequate water, bacteria ferment the feed and produce volatile fatty acid.  The rumen develops primarily because of the volatile fatty acid butyrate.  You have all of this going on, plus heat produced during fermentation, which helps keep the animal warm,” says Erickson.
The challenge for providing free access to water is that it freezes in cold weather.  “When the calf is done drinking milk, provide some water.  We understand that it’s going to freeze, but the calf may have a chance to drink some,” he says.

“The other challenge, if you don’t feed water to calves, and they are fed a high-protein milk replacer or even just a lot of milk replacer, the osmotic balance is upset.  These calves will actually die of dehydration even though they are getting a lot of milk replacer.  Data published in the Journal of Dairy Science says that when we feed a very high protein milk replacer, water intake goes up,” he say.  Animals that consume a lot of protein must drink more water.  

“If we are feed calves a lot of milk or milk replacer, we need to make sure they have water.  Some people overlook this because they assume that the fluid in the milk or replacer is adequate,” Erickson says.

“One problem we see all year long, but can be exacerbated in the winter, is that often calf buckets are not thoroughly cleaned out.  People are putting starter in on top of remaining starter, and not cleaning their water buckets.”  When an animal is stressed (as in cold weather) the immune system is hindered and pathogens can take hold.
Plastic buckets generally have lots of little scratches that can harbor microbes.  Suddenly you may have calves with diarrhea or with salmonella.  We need to be diligent about cleaning calf pails.

Some farmers feed milk in a bucket and then put water in, right behind that, with the milk residue still in the bucket.  “The calf is slobbering in the bucket, and there is still some milk or replacer in the water, which makes a perfect environment for microbial growth.  In our university herd, we feed milk in stainless steel pails.  These are much easier to clean, though very expensive,” says Erickson.  They probably pay for themselves, however, in fewer sick calves and less treatment costs.

Any time calves are stressed—whether winter cold or summer heat—this is when problems occur.  “As the calf gets older, lower critical temperature is about freezing, and as she gets older yet, it drops below that.”  A mature cow can be healthy and comfortable at lower temperature.

A baby calf, however, is very susceptible to cold stress, even when temperatures are not very cold.  The small young calf doesn’t have enough body mass to keep warm, and not enough insulation.  Jerseys, per unit of body size, actually have more surface area per body weight than a Holstein even though they are smaller.  They may be more vulnerable to cold stress because of the potential heat loss from all that surface.

James tells dairymen to not be in a big hurry to wean calves, especially in winter.  “We normally wean dairy calves at about 8 weeks, but in winter we may want to extend that to 10 or 12 weeks, especially in bitterly cold weather.  By then calves will probably be eating 3 to 5 pounds or more of calf starter per day.  We need to make sure they have enough intake and enough rumen development to start eating well,” James explains. “We also need to make sure they are getting enough liquid, especially in the first 30 days, and we don’t want to wean them too soon because of their energy requirements.”