WHEY AND SKIM: WHAT ARE THEY?
Whey and skim proteins have certain differences but are both derived from whole milk. While skim milk is simply whole milk with the fat removed (80% casein and 20% whey), high-quality whey milk replacer is abundant in bioactive content which is essential in supporting a calf’s immune system and influencing its growth. This is indicative of colostrum which contains three times more whey protein than regular milk.
However, despite the nutritional differences, skim and whey protein milk replacers offer comparable benefits to calf growth providing the manufacturing process is of high quality, which is true in the case of Volac’s product, Imunopro®. Using low quality raw materials and aggressive manufacturing processes will result in a low quality milk replacer, which will ultimately affect the performance of your calves.
A SIMILAR IMPACT ON CALF GROWTH
It’s a common misconception that calves fed skim milk replacers achieve superior health and performance results.
A study, from the Journal of Dairy Science on ‘a comparison of milk protein sources in diets of calves’, found that milk replacer diets varying in the ratio of dried skim milk to whey protein concentrate had no effect on the health, growth or apparent digestibility’s in Holstein calves – therefore, dried skim milk and whey protein concentrate were comparable dairy protein sources for milk formulas for calves up to 8 weeks.
If you would like to know more about this research, please read our technical bulletin.
QUALITY IS CRUCIAL
The processing method of the dairy protein, for both skim and whey, plays a part in the quality and consequently digestibility and calf performance. It has been shown that at higher processing temperatures of 85°C, over 60% of whey proteins were denatured within 30 minutes, compared to only 15% at 65°C.
With this in mind, Volac use low temperature ultrafiltration to process the liquid whey to ensure a high proportion of the natural immunoglobulins and valuable bioactive proteins are retained in the finished milk formulas. It is these immunoglobulins that are essential to calf health (supporting defence mechanisms) and influence the growth and development of the young animal.
Though there are arguments for both whey and skim, it is important to remember that in particular not all whey is the same – high quality concentrated whey protein such as Volac’s Imunopro® calf milk base, will give calves the best opportunity for growth and development.
It’s also worth keeping in mind the casein content in skim-based milk replacers has been falling since the abolition of subsidies for defined skim content in 2006.
Whether you favour skim or whey-based replacers, quality is crucial.
THE TRUTH ABOUT THE ABOMASAL CLOT
When whey is the only source of dairy protein in a milk formula, no clot will form within the abomasum, due to the absence of a protein called casein. Skim replacers however, do contain this protein, which reacts with the enzymes rennin and pepsin to form a clot in the abomasum. Traditionally, this clot was thought to be of major importance in regards to nutrient digestibility.
Recent research though has shown that a clot is not required to maximise calf performance - its absence had no significant impact on calf appearance, appetite and vigour. And in some cases, albeit rare, calves simply don’t form an abomasal clot, regardless of how much casein they ingest. In short: an abomasal clot is in no way essential to achieve optimal calf development.
Skim and whey protein milk replacers offer similar health and productivity benefits depending on the manufacturing process, but are they comparable when it comes to digestibility?
Here too, research shows no difference in the digestibility of dry matter for calves on either skim or whey milk replacers from weeks two to eight. Calves can digest whey protein concentrate just as well as they can digest skim milk protein.
IN CONCLUSION: DON’T OVERLOOK WHEY…
When whey and skim replacers of high quality are put side by side, their results on calf performance are comparable. Good quality whey-based milk formulas result in calf growth at least as good as that achieved with high quality skim-based milk replacers.
For more information, we recommend reading our technical bulletin.
Published on: 28 April 2020
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