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3 things to consider when designing the milk feeding program

Alyssa Dietrich for Progressive Dairy Published on 02 July 2020
dairy calves

When feeding whole milk or milk replacer to calves, there is not a one-size-fits-all solution for dairy producers. The choice of which one to feed often comes down to each farm’s whole milk availability, its costs, the current milk price and the farm’s management capabilities. Whether you’re feeding whole milk, milk replacer or a combination of the two, here are three things to consider.

Protein-to-fat ratio

Dairies normally feed higher protein milk replacers to calves, but when feeding whole milk, the percentage of fat will always be higher than the percentage of protein available. Let’s take a look at the pros and cons of feeding a higher-protein-than-fat milk diet to calves in Table 1.

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pros and cons of feeding higher protein to calves

During certain economic circumstances, like low milk prices or low demand for salable milk, it may make sense for a farm to feed salable whole milk instead of milk replacer. Normally it is expensive to feed high fat, and that has been a reason to not overfeed it. Be sure to consider how much the fat in your liquid diet costs.

Before starting or switching to whole milk, a dairy should understand the amount of protein and fat their milk contains. For farms that want to feed whole milk but are also looking for lots of lean growth and starter intake in calves, there are options for adjusting the protein-to-fat ratio to get it closer to a 1:1 ratio. Products known as whole milk enhancers or balancers are designed as protein and vitamin/mineral additives for whole milk. In addition, high-protein milk replacers can also be utilized in this way.

Feeding rate 

The feeding rate refers to the actual amount (total grams of protein and fat) the calf is consuming. When selecting a milk replacer, the main area of focus is often on the protein and fat percentages. Milk replacers are often referred to by their crude protein content followed by the crude fat content, like 20:20, 22:20 or 24:18. As for whole milk, Table 2 can help you identify your protein-to-fat percentage.

dry matter protein-to-fat ratio

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Although we often refer to liquid feed by the protein and fat percentages, calves require total grams of protein and total grams of fat to meet their maintenance and growth needs. Therefore, the amount of milk replacer or milk fed is key to reaching growth goals. Selecting the appropriate protein-to-fat ratio to fit the feeding rate is a strategy for balancing protein and fat. In this way, neither protein or fat are a significantly limiting nutrient, and calves are efficiently utilizing feed without wasting protein or energy.

For example, if you are feeding a 24:18 milk replacer at a low rate of 1 pound per day – energy would be limited, and the calf would not utilize all the protein fed to her. Paying for protein that is not being utilized is a waste of money. A better solution may be feeding a 24:18 milk diet at the recommended rate of 2.5 pounds per day. This will increase the amount of energy the calf is consuming; hence, energy is no longer limited, and the calf will utilize more protein.

When feeding milk replacer, a higher feeding rate usually requires a higher protein-to-fat ratio. This is in order to balance protein allowable gain with energy allowable gain and avoid limiting either nutrient. At a feeding rate of 2.25 to 2.5 pounds per day, the protein-to-fat ratio I recommend is a 1:2 to 1:4. This is an efficient way to utilize protein and fat so that neither is a limiting nutrient. Conversely, the protein-to-fat ratio in whole milk is less than 1, meaning that energy is usually overfed.

Energy requirements 

A calf’s energy requirements change in times of stress such as health challenges, seasonal changes and so forth. In these cases, calves could benefit from being fed a diet higher in fat.

I like to think of excess fat (usually seen with a whole milk diet) as a way to provide an energy “cushion” that can help calves in times of stress. An example of a higher fat diet helping calves overcome health challenges was demonstrated in a Dutch study. It showed that calves fed a free-choice high-fat milk replacer had less respiratory disease compared to calves fed a free-choice low-fat milk replacer.

In addition to health, calves require higher energy consumption to keep them warm during cold stress months, so increasing the amount of fat fed to calves in the winter may be needed in order to reach your growth goals.

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What about energy requirements during heat stress? The biological strategies used to cool the body use up energy, therefore increasing calf energy maintenance requirements. Unfortunately, adding more fat to a calf’s diet could lead to less starter intake, which may already be depressed in times of heat stress. In order to avoid reduced average daily gain in the summer, offer fresh, free-choice water and starter at all times, and utilize shade and fans when possible.

Measuring milk feeding efficiency

Any time you change a liquid feed ration, consider monitoring these three effects: 

  1. Has growth changed? I recommend weighing calves at birth, weaning and three weeks post-weaning. Ideally, a calf’s weaning weight should be double its birthweight or at an average daily gain (ADG) of 1.6 to 1.7 pounds. During post-weaning, the ADG from 8 to 12 weeks old should be the same or higher than the calf’s pre-weaning ADG (1.6 to 1.7 pounds).

  2. What is your cost per pound of gain? Cost per pound of gain tracks what you are putting into the calves against the kind of gain you are measuring. When tracking this on dairies, I benchmark changes to a calf program to see if their current cost per pound of gain makes sense. When the plane of nutrition is changed, it is important to make sure you see the expected return.

  3. What health events have increased or decreased? While feeding milk or milk replacer, make sure that you're not seeing an increase in scours or any digestive issues. Bloating or diarrhea may occur in calves when you change the liquid diet. Post-weaning issues such as coccidiosis and respiratory disease often relate to poor starter grain intake. I advise dairies to measure starter intake during the weaning transition period before calves are moved to post-weaning groups. I like to see calves consuming 3 to 4 pounds of starter grain for at least three days in a row before they are completely weaned.

There are many other health- and management-related arguments for and against feeding milk replacer and whole milk. Like I said, there is no “one-size-fits-all” solution. Work with your calf nutritionist as well as your management team to crunch the numbers and find the best milk feeding option for your herd.  end mark

References omitted but are available upon request. Click here to email an editor.

Alyssa Dietrich
  • Alyssa Dietrich

  • Calf and Heifer Specialist
  • Cargill Animal Nutrition
  • Email Alyssa Dietrich

PHOTO: Although we often refer to liquid feed by the protein and fat percentages, calves require total grams of protein and total grams of fat to meet their maintenance and growth needs. Therefore, the amount of milk replacer or milk fed is key to reaching growth goals. Photo courtesy of Cargill Animal Nutrition.

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