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Rethinking how we feed milk to pre-weaning calves

Amanda Fischer and Michael Steele for Progressive Dairyman Published on 16 July 2018
Calves being feed

In our previous article, “Colostrum, transition milk and maternal impact: There’s still a lot to learn,” we discussed the overwhelming amount of information left to be uncovered in regard to the newborn dairy calf and colostrum management.

Similar to colostrum nutrition, there is still an abundance of knowledge left to be discovered regarding the next phase of nutrition for the dairy calf: milk feeding.

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The concept of milk nutrition and milk feeding regimens is one of the most controversial topics in calf management, with the main debates centering around the amount of milk to feed to calves and the contrast between whole milk and formulations of milk replacer.

Recently, research from our group and other groups around the world has begun to shed new light on these topics.

High vs. low planes of milk nutrition

The amount of milk we should feed to calves during the pre-weaning phase is one of the largest topics of debate among producers, industry professionals and researchers. Feeding a high plane of milk nutrition entails feeding approximately 8 to 10 litres of milk per day, while producers using a low plane of nutrition generally feed calves under 5 litres of milk per day.

Before making a decision on which plane of nutrition to follow for your calves, it is important to understand the main arguments for both sides:

  • Against high plane of nutrition: It is too costly to feed large volumes of milk per day for the growth rates achieved. Moreover, feeding a high amount of milk reduces starter intake, which makes the calf more susceptible to health and production challenges during the weaning transition.

  • In favour of high plane of nutrition: Leads to improved animal welfare, for in nature calves would typically consume a high amount of milk from the dam in multiple small meals throughout the day. There is also increased growth during early life with the potential of improving productivity later in life.

Both arguments have valid points and need to be considered. First, even when farmers are feeding a high plane of nutrition, during the first weeks of life calves are still restricted to levels of 10 percent of bodyweight (approximately 4 to 6 litres).

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This is a large restriction in energy when the majority of nutrition comes from milk – for during the first weeks of life calves are unable to consume a significant amount of starter. This is typically why we see depressed weight gain (less than 500 grams per day) when calves are fed at 10 percent of bodyweight during the first week or two weeks of life.

Surprisingly, experiments at our research farm have demonstrated all of our calves are able to achieve 10 litres of milk consumption using an automated calf rail (four to five meals per day) during the first week of life, which translates to greater than 800 grams per day of growth.

While these numbers are impressive, the majority of producers argue feeding 10 litres of milk in four to five meals per day is not possible without an automated feeding system. This leads to feeding large meals by bottle less frequently (e.g., 4 litres two times per day).

However, there are concerns feeding a large meal size may lead to an inflamed abomasum, abomasal overflow into the rumen and reduced insulin sensitivity due to the large amount of glucose provided to the calves all at once. For these reasons, farms feeding calves by bottle twice a day typically restrict meals to only 2.5 litres.

In regard to these concerns, our group has demonstrated during the first weeks of life, calves are able to handle large meal sizes (4 litres two times per day) without any impact on gut health or insulin sensitivity. Moreover, a recent study from Norway showed 2-week-old calves allowed free access to milk consumed meals greater than 5 litres – with some even consuming 9-litre meal sizes – without any overflow into the rumen.

This suggests we have largely underestimated how much calves are able to consume in a single meal. It is obvious feeding calves more frequently is better, as it is similar to how calves would nurse in nature; it also allows for a steady intake of nutrition throughout the day. That said, if your management style only allows for 2X feeding, that does not mean you cannot feed larger meal sizes (greater than 2.5 litres) in the first weeks of life in order to maximize growth while starter intake is low.

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In summary, if you are feeding either a high or low plane of nutrition, yet still restrict calves to 10 percent of bodyweight during the first weeks of life, we encourage you to feed calves larger meal sizes at this time in order to maximize growth while starter consumption is insignificant.

On the flip side, if your main reason for feeding a low plane of nutrition is concern about starter intake and weaning challenges, we believe it is worthwhile to consider feeding more milk during the first weeks of life, when the amount of milk fed cannot affect the marginal level of starter intake consumed.

Feeding whole milk vs. milk replacer

Similar to the debate about high versus low planes of milk nutrition, it is almost impossible to talk about milk feeding without discussing the pros and cons of milk versus milk replacer. Again, before making a decision, we should consider both sides of each argument:

  • Against milk replacer: The formulations are not natural compared to whole milk, and it is not cost-effective.

  • In favour of milk replacer: The nutrition is consistently the same, and it is clean and convenient.

While there are many practical considerations for this debate, the science is often difficult to interpret because comparing milk to milk replacer is never the same as comparing apples to apples. For instance, many of the studies that compare the two have different feeding rates and nutrient composition between milk and milk replacer treatments.

Therefore, we can never really infer what is the best method based on these studies.

From a practical standpoint, it is clear calves are able to gain well on both milk and milk replacer. It is also obvious gut health issues can occur when feeding milk, mainly from feeding milk contaminated with pathogens or antibiotics, or when feeding milk replacer, in which problems generally occur due to ingredient quality.

When speaking about nutrient quality, the main concern comes from the large quantity of whey permeate in some milk replacer formulations which, in turn, drive up lactose concentrations. To be more specific, in dried milk, the lactose concentration is 35 percent, while in most milk replacers it is closer to 45 percent, which comes at the expense of fat in the formulation.

We have two main questions about this approach to milk replacer formulations: Does the large amount of lactose disturb the barrier function of the gut? Does it disturb metabolic function?

Our lab and other labs around the world are currently working on this topic, with preliminary data showing feeding high-lactose milk replacers does impact glucose clearance in the blood of the calf. This suggests these formulations likely do impact the metabolic function of the calf. We currently have further studies in the works though, so stay tuned for more results to come to support this argument.

Milk feeding regimens in pre-weaning calves is a controversial topic, with the main debates concerning the amount of milk to feed and whether to feed whole milk or milk replacer. Regardless of feeding a high or low plane of milk nutrition, producers should consider feeding an elevated level of milk (greater than 2.5 litres per meal) during the first weeks of life to maximize growth.

While less is known about the effects of feeding milk versus milk replacer, preliminary results suggest feeding high levels of lactose in milk replacer may affect metabolic function in the calf. In the future, more research on both topics will better explain the benefits and potential pitfalls of these milk feeding regimens in order for producers to make informed and confident decisions on how to feed their pre-weaning calves.  end mark

PHOTO: Calves receiving nutrition. Photo by Karen Lee.

Michael Steele is an assistant professor of ruminant nutrition for the University of Alberta Department of Agricultural, Food and Nutritional Science. Email Michael Steele.

Visit “Colostrum, transition milk and maternal impact: There’s still a lot to learn.” to read Steele and Fischer’s previous article.

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