What Way is the Right Whey?

Words by Karen Fraser – Technical Specialist

Autumn is often seen as a great time for rearing calves due to warmer weather, allowing calves to go outside sooner than in spring. However, autumn-reared calves can still face significant challenges, even before being born.

Cows may experience reduced feed quality and quantity, heat stress, and inflammation from summer, along with limited rumen space due to the growing calf. Calves born to cows exposed to heat stress have been shown in studies to have a lower birth weight, weaning weight and compromised passive immune transfer. Calves born from compromised cows are more vulnerable and can face higher bacterial loads from their environment and colostrum due to higher temperatures. To address these issues, recent changes based on the latest NASEM (National Academies for Science, Engineering, and Medicine) guidelines suggest addressing nutritional gaps in transition milk and whole milk to meet the needs of calves.

At our spring roadshow seminars, we discussed areas of weakness that lead to many issues seen across the country. Outside of our roles as ‘The Calf Experts’, Stacey Cosnett and I both work for Farmlands in the technical space. Our passion is to reduce stress for both animals and the people caring for them. We encourage focusing on the basics and doing them well. With my practical calf-rearing skills and Stacey's academic expertise, along with two of our knowledgeable colleagues, we have become a strong team covering weak industry areas. This led to the development of Reliance Blue Boost electrolyte, a now essential tool for rearers.

The second focus was on other stress-induced issues and how to combat inflammation, bacterial loads, manage micronutrient deficiencies, and coccidia control to support optimum calf health. This resulted in developing ‘Reliance Level Up’, a whole milk additive designed with the latest NASEM guidelines in mind. It includes components that protect the respiratory and intestinal tract, increase dry matter intake, balance essential nutrients, and control coccidiosis early on. Level Up has been in use for three seasons with excellent testimonials. Another area we explored was the composition of colostrum and whole milk and the importance of protein for optimum growth. Whole milk is made up of 80% casein protein and 20% whey protein, whereas colostrum is made up of 35% casein protein and 65% whey protein. The albumins and globulins (including immunoglobulins) which make up whey protein in whole milk are essential in supporting the immune system and influencing the growth and development of the calf. Colostrum has three times more whey protein than whole milk, making whey crucial for calf success.

For the first few weeks of life, calves’ digestion is like that of a monogastric animal, with the abomasum the primary site for digestion. During this period, calves rely on milk or milk replacer for carbohydrates and protein. When whole milk enters the abomasum, it forms a clot due to the action of rennin, pepsin and hydrochloric acid, then is slowly digested and released into the small intestine. Here, whey proteins are further broken down and absorbed, providing essential energy. In contrast, milk replacers based on whey do not form a clot, but recent research shows that this does not negatively affect calf performance. Whey protein is one of nature’s superfoods for young calves, human babies, and bodybuilders.

Digestion difference between Casein calf milk replacer and Whey calf milk replacer:

Casein Calf Milk Replacer

This type of milk replacer has casein, the main protein found in skim milk. When ingested, it forms a curd in the calves' abomasum, which is digested slowly, providing a steady release of nutrients. This slow digestion process has traditionally been believed to support better nutrient absorption and overall digestion. However, not every calf can curd even the highest curding CMR or whole milk, especially when stress has been compounding early on. Research shows that some calves do not form an abomasal curd despite ingesting a clotting milk replacer, but this absence does not significantly affect their appearance, appetite, or vigor. In a study with 29 calves, ultrasonography revealed that 21 calves formed a large curd mass, while eight did not. The absence of curd formation did not affect the calves' blood parameters or overall health, suggesting that some calves may have an abomasal dysfunction or a congenital lack of curd-forming enzymes. Hence, some calves struggle more than others when transitioning to casein CMRs, but they could have already been struggling on whole milk.

Whey Calf Milk Replacer

In contrast, whey calf milk replacers have whey proteins, which come from the liquid left after cheese production. These proteins do not form a curd in the abomasum, leading to faster digestion and nutrient absorption. Despite the lack of curd formation, whey-based milk replacers can support calf growth and health just as effectively as casein-based ones. Whey proteins are highly digestible, and when processed correctly, they can provide the necessary nutrients for the best calf performance. Whey powders result in fewer transition issues, less scours and quicker digestion, leading to earlier consumption of calf starter. In New Zealand, calves need energy levels of 20-22% fat, as energy drives protein. Some lowfat CMRs may not be suitable for spring-born calves that burn energy to stay warm. The NASEM recommendations show that protein becomes the limiting nutrient for calf growth. Often, rearers using 18% fat and 22% protein see slower growth rates, lower frame and muscle, which can prolong the rearing process and expose calves to health challenges. Considering these factors and the many calls we receive each year about transitioning issues, health problems, and slow growth rates, we developed Reliance Kiwi Power Whey. We took a favourite whey product from 23% protein to 26% protein because we want calves to succeed with early bone and muscle growth. Reliance Kiwi Power Whey can be fed from day four and includes the proven additive Actigen to support calves during environmental challenges. It also contains a safer coccidiostat, decoquinate, which makes it safer around dogs and offers better energy and protein levels. Made from New Zealand raw materials, it supports local milk processors and addresses local challenges.