Calf rearing has not only become very technical, but there are now many different options for getting the best performance at this critical stage of development.
A recent CalfChat evening hosted on social media threw up an interesting fact; 85% of the participants fed milk replacer to their calves. This figure is even greater than the 60% flagged up in a recent survey of Irish dairy farmers by Bonanza Calf Nutrition.
Dr. Christine Cummins, of Bonanza Calf Nutrition, has said that those rearers have to navigate a “mind-boggling’’ process to select the best milk replacer for their calves.
“With so many options on the market, making that choice is not easy and only they know what is important in a milk replacer to them,’’ she said
In a CalfChat poll, 88% prioritised protein, more specifically 27% prioritised crude protein levels and 63% the type of protein.
Understanding milk replacer
“CalfChat asked participants for their thoughts on the different aspects of protein and the results illustrated that there is a varied understanding of proteins in milk replacer,’’ Dr. Cummins explained.
She recommends that to understand the role of milk replacer, it is always useful to reflect on the content of cow’s milk.
The protein in cow’s milk contains both casein and whey; the former is digested in the same way that skim is in milk powder.
“These proteins work together as a team with whey being what could be referred to as the ‘quick hit’ protein heading out in front of skim which stays behind for a slower release to the calf (Figure 1)’’, Dr. Cummins said.
It is also important to understand the difference between whey and skim powders.
A recent survey carried out by Bonanza Calf Nutrition showed that whey was the milk replacer used on the farms of 65% of participants.
But the question is, do they know what this means?
Protein and other ingredients
In another poll, CalfChat participants were asked to select from a list of proteins, what they believed to be ‘most like cow’s milk’.
The majority had an excellent understanding that the correct answer was low heat skim and whey. But when asked about the difference between the digestion of high heat skim and low heat skim, 50% did not know (Figure 2).
Low-heat skim is skim produced using low drying temperatures, a more expensive process than using high temperatures, but one that provides more protein availability to the calf and improves the clotting of the milk.
The quality of that skim affects the speed at which the milk will clot (Figure 3), Dr. Cummins explained.
“The longer a clot takes to form, the more the skim that will have passed through the abomasum (stomach) of the calf before clotting takes place,’’ she said.
This can also affect the firmness of the clot, she adds.
“A clot will not be as firm in a slow clotting process 60 minutes after clotting if less has clotted and more has passed through.
“If using a skim powder, it is important to know that it is going to clot and the protein will be available for use by the calf.’’
A bonus to the clotting for slow-release protein is the trapping of fat trace elements and vitamins for slow release, aiding digestion of these elements.
Gut health
Rearers who are feeding a high level of whey to calves with an underdeveloped or compromised gut, need to be aware of the risk of scouring.
Gut integrity is key in the ability to process protein. If it is compromised a big wave of protein passing through cannot be absorbed and therefore it will have to be processed otherwise.
In the survey carried out by Bonanza, there was a range of feeding rates: 45% of participants fed 875g/day or more of milk replacer, 39% fed 700-850g and the remaining 16% offered less than 700g to their calves.
One important note is that there can be a big difference in protein percentage between powders.
Skim contains approximately 35% protein; this was understood by 61% of CalfChat participants. However, the understanding of the protein content of whey powder is less widely appreciated (Figure 4).
At 6-12%, whey powder has a low protein content. This can be described on the list of ingredients as whey powder, whey, or whey protein.
In contrast, whey protein concentrate (WPC) ranges from 36-80% protein but being very expensive it makes up just a portion of protein levels.
It is also important to note that while some whey powders may technically have the same level of protein as skim, it cannot be confirmed as nutritionally equal to skim.
“Even a high quality whey is a fast-digesting protein that lacks the clotting ability of good quality skim,’’ Dr. Cummins said.
What’s on the label
Even with a label to scrutinise, it can be difficult to tell what is actually in a calf milk replacer. The crude protein, fibre and ash does not tell us enough about the ability of the calf to utilise ingredients in the product.
Ingredients should be listed in order of the most to the least inclusion rates and each ingredient should be listed individually.
Crude protein is loosely associated with digestibility of the protein and levels are declared using a standard calculating system.
Dr. Cummins warns that this system over declares vegetable proteins, such as wheat, and under declares milk proteins.
Higher ash can include higher levels of milk calcium and phosphorus which are required for bone growth they should be sourced from milk rather than an additional ingredient such as calcium carbonate (limestone). Milk sources are more available to the calf and so as a guide aim for ash of 7.5 – 8.0 % with no added calcium and low sodium levels.
Fat must be digestible to the calf but the level of these fats can also be difficult to establish.
A blend of fats that provides a range of natural fatty acids that are similar to cow’s milk is preferrable, Dr. Cummins advises.
“It’s an added bonus if the right amounts of these fatty acids are provided with palm and coconut supported with other fats, such as buttermilk, linseed oil and rapeseed oil, to provide a desired balance of Omega 3:6 and boost immunity,” she said.
Watch out for the next CalfChat event being held on December 8, which will focus on challenges during early life transitions.
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