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Milk replacer: How to decide what to feed and how much to feed

Drew A. Vermeire for Progressive Dairy Published on 13 May 2020

“Doc, what kind of milk replacer should I feed, and how much?”

As a calf ranch consultant, this is the most common question I hear. The answer depends on several factors, such as who owns the calves, how do you get paid for raising the calves and what are the objectives in raising the calves.

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Some operations own the calves and raise them as replacement heifers for their own dairy. In this case, the highest return-on-investment (ROI) is to feed a higher quantity of milk replacer with the objective of doubling the calf’s birthweight by day 56 of age. Calves fed in this manner produce more milk in every lactation with a similar total cost of growing the heifer from birth through freshening. In the case of dairy beef operations where the calves are owned by the calf ranch, the objective is to produce calves with minimum cost of gain (COG) to maximize profit per head. If dairy beef calves are owned by an outside party and the calf ranch is paid a daily stipend to provide feed and care, it might be financially best for the calf ranch to minimize daily cost, even though calf performance suffers and COG is substantially higher than other feeding options.

Nutritional needs in a nutshell

To enable us to make sound business decisions, some understanding of calf nutritional needs and performance is required. As a generalization, calves need energy for maintenance and protein for gain. As energy intake increases, calves have the potential to gain more weight, and the weight gain requires more protein to grow muscle and bone. To illustrate this concept, let’s consider a calf at maintenance gaining up to 2 pounds per day. At 68ºF, calves need approximately 1,800 kilocalories (kCal) of metabolizable energy and 35 grams of protein per day for maintenance as shown in Table 1. As milk replacer intake increases, energy intake increases at the same rate, but the need for protein dramatically increases by a much higher rate. I find it fascinating that an increase in daily milk replacer intake from 14.8 to 19.4 ounces, an increase of 4.6 ounces which is 0.28 pounds, can increase daily gain by 0.5 pound. That’s a great ROI trading less than 0.33 pound of milk replacer for 0.5 pound of calf gain!

041020 vermeire milk replacer tbl1

Notice that a calf at maintenance, that is to say that calves not gaining any weight, need only about 7.5% protein in milk replacer, but for calves to gain weight, they need more protein in milk replacer.

The amount of energy calves receive every day, which we measure in calories, is primarily due to the amount of milk replacer fed. It is a myth that the level of fat in the milk replacer substantially impacts energy intake. Doubling the fat level from 10% to 20% fat simultaneously reduces lactose level by 10% and only increases metabolizable energy content from 1,860 to 2,087 kCal per pound, which is only a 12% increase in energy. On the other hand, increasing the amount of milk replacer fed from 8 ounces to 10 ounces per feeding increases energy intake by 25% – twice the impact of doubling the fat content.

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Other factors that impact the nutritional needs of calves are calf bodyweight, ambient temperature, stress and colostrum intake. We generally feed all calves the same amount of milk replacer each day, regardless of bodyweight. At any given level of intake, smaller calves require more protein than larger calves because they have lower maintenance requirements, therefore, they have more energy available for gain, which requires more protein. At temperatures colder than 68ºF, calves’ energy needs increase due to increased heat loss. To maintain rate of gain, we need to feed about 33% more milk replacer per day at freezing and 60% more milk replacer when temperatures fall to 0ºF. Stress from shipping or other stressors increase maintenance needs by about 10% for 14 days, so keep this in mind when feeding shipped calves. Calves without adequate colostrum will not perform as well as calves with adequate colostrum, so it pays to monitor serum protein levels and tune up your colostrum program to ensure adequate colostrum intake.

The final piece of calf nutrition involves development of the rumen. Calves are born in a “pre-ruminant” state in which feeds are digested in the small intestine with no rumen function. Development of the rumen is primarily due to fermentation of starch, starting with small amounts and increasing as daily starter feed intake increases. Calf starter feeds should be high in fermentable carbohydrates from corn and/or barley, soybean meal, canola meal and other fermentable ingredients. Avoid high-fiber ingredients such as sunflower meal, cottonseed or soyhulls, and definitely avoid high amounts of ingredients derived from ethanol production such as distillers dried grains, brewers grains, etc. Starch in these ingredients was already fermented in the ethanol plant leaving non-fermentable fractions that are better suited in cow rations but should not be used in calf feeds. The most expensive starter feed is a fraction of the cost of the cheapest milk replacer. It’s best to feed the highest-quality calf starter feed to maximize intake and rumen development. Calves will more readily consume textured feeds which are a blend of corn and/or barley, oats, supplement pellets and liquid molasses. Look for feeds with high amounts of grain and minimize feeding fiber until after calves are weaned.

Calf performance helps us decide what to feed

As a basic philosophy, the most profitable calves are fed the maximum amount of milk replacer per day for the minimum number of days. What’s the maximum? In this case, the maximum is the level of milk replacer needed to achieve the rate of gain desired and maximize calf starter feed intake because our overriding goal is to wean calves off of milk replacer as soon as possible when they can thrive with starter feed alone. To illustrate this concept, Table 2 shows data derived from research published by Hill et al.

041020 vermeire milk replacer tbl2

This study was very clever because calves fed treatments 1 and 2 were fed for the same number of days, while calves fed treatments 1 and 3 were fed the same total amount of milk replacer. At day 84, calves fed treatments 2 and 3 weighed 20 and 27 pounds more, respectively, than calves fed the traditional 1 pound of 20:20 milk replacer. The option of feeding calves with treatment 3 should be of tremendous interest to calf producers because calves weighed more than the traditional feeding program and with a lower COG. Additionally, calves weaned early can move to transition pens at a younger age, and the calf ranch can turn hutches at a faster rate with less labor per calf. Can everyone wean calves at 28 days of age? Probably not, because their management is not at a high enough level, but it is reasonable and economical to wean calves at 35-42 days of age, which is earlier than calves are weaned on most operations.

The choice of what milk replacer to feed should be determined by the desired level of calf performance, not by price. Protein level depends on potential gain and level of feed intake. With proper amino acid supplementation, non-milk ingredients such as wheat protein, soy protein concentrate and plasma, especially in combination, result in equal or better performance than with all-dairy milk ingredients and with a lower price and lower COG. Good feed is good medicine and feeding an amount of milk replacer that enables the calf to gain weight has an immediate benefit in healthier calves and more economical gain.  end mark

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References omitted but available upon request.

PHOTO: Getty Images.

Drew A. Vermeire
  • Drew A. Vermeire

  • Nutritionist
  • Nouriche Nutrition Ltd.
  • Email Drew A. Vermeire

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