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The most important thing for feeding dairy calves is to get colostrum as soon as possible into a newborn calf. After that, the calf needs adequate milk or milk replacer until weaning age. 

Some dairies feed their calves milk, but most of them use milk replacer. If you have a dairy you may choose to feed the calves on milk, or even if you just have a family milk cow that gives extra milk (or a neighbor who has extra milk you can buy), you can raise a calf or two on milk. 

Otherwise, your only option is feeding dairy calves milk replacer. There are many milk replacers on the market, and you want to make sure you use one that is adequate for optimum growth and health of the calf. 

In years past, some dairy farmers fed a limited amount of milk, because they wanted to wean calves early — since milk or milk replacer is expensive. But weaning early is not normal, and calves stay healthier if they can be on milk or milk replacer longer. 

The old way was feeding dairy calves two quarts of milk replacer in the morning and two quarts in the afternoon, using a milk replacer containing 20% protein and 20% fat. This barely meets maintenance requirements in moderate weather. Milk itself will vary by breed but is somewhere between 26 and 28% protein and from 28 to 32% fat. So you are already shortchanging the calf by feeding milk replacer. The reasoning was to keep the calf hungry so it will eat more dry feed sooner. 

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 at three weeks old will drink at least eight quarts a day if allowed to drink all it wants. 

Dr. Pete Erickson, Extension Dairy Specialist, University of New Hampshire says the standard products have 20% protein, 20% fat, and some have 26 to 28% protein, with some as high as 32% protein. When a calf is young, the higher the protein content, the better. 

There are many ways to feed milk replacer to calves. ”What we generally do in the warmer months is feed milk replacer twice a day. In the 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, and fat has a lot of value for providing calories. 

“The other thing we are trying to do is get the rumen developed, so we have to feed the calf some kind of calf starter. The 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’re 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 will be fermented,” he explains. 

“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,” he explains. 

In hot weather, on the other hand, you don’t want calves creating more body heat. When it’s hot, cattle eat less. With the heat of fermentation, their heat load increases and they don’t feel like eating, so you feed less roughage. “Conversely, in the winter, you feed more roughage to help them maintain core temperature. We get the rumen developed by feeding calf starter, and hopefully increase internal core temperature. 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 the calves as we can.” 

Calves also need water, and not just in the form of milk or milk replacer. A study in the 1980s looked at feeding dairy calves the same diet but with half the calves having access to free-choice water and the other half didn’t. There was an increase in average daily gain in the calves that had free-choice water, an increase in starter intake, etc. 

When a calf drinks water it goes to the rumen, while milk replacer or milk goes to the abomasum (true stomach — where it is digested) because of the esophageal groove. Bacteria that reside in the rumen must have a watery environment; you can’t shortchange the ruminant on water or digestion is impaired.  

“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. All of this is going on, plus heat produced during fermentation, which helps keep the animal warm,” says Erickson. 

The challenge for watering cattle in winter is that it freezes in cold weather. “The recommendation in winter is that when the calf is done drinking milk, you 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 is, if you don’t provide water to your calves when feeding a high-protein milk replacer or even just a lot of milk replacer, the osmotic balance is upset. These calves can 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 high-protein milk replacer, water intake increases,” he says. Animals that consume a lot of protein drink more water.  

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

Calves generally need six to nine quarts of milk or replacer daily, split into three feedings. “I recommend feeding two to three quarts first thing in the morning, and again midday, and at the end of the day. Also, make sure the calves have calf starter. If you feed a texturized calf starter, you don’t necessarily have to feed hay with it. If you feed a pelleted starter, you probably should feed some good-quality hay with it, and make sure they eat it. Some dairies chop hay to make sure it is fine and palatable. Don’t feed what is often called ‘heifer hay’ (something not good enough for lactating cows),” says Erickson.  

“One problem we often see is that the calf buckets are not thoroughly cleaned out. People put starter on top of some remaining starter, and are also not cleaning their water buckets. Plastic buckets generally have lots of little scratches that can harbor microbes. Suddenly you may have a bunch of calves with diarrhea or salmonella. We need to be diligent about cleaning calf pails.” 

When feeding dairy calves, some people feed milk in a bucket and then put water in, 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. So keep those buckets clean. In our university herd, we feed milk in stainless steel pails. These are expensive but much easier to clean, ” he says. They probably pay for themselves in fewer sick calves and fewer treatment costs. 

“We feed milk in stainless steel pails and when the calves finish, we pull out those pails and put water buckets in. All buckets are cleaned daily, including starter buckets — so we are not putting new starter on top of old. In summer, the warmer temperatures encourage mold growth,” he says. 

Originally published in Countryside September/October 2021 and regularly vetted for accuracy.