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Mother knows best: Calf care lessons learned from the milk cows produce

Progressive Dairyman Editor Karen Lee Published on 30 April 2019
calf drinking a bottle

During the gestation period, a cow does all it can to grow an embryo into a calf. The dam’s contributions for its offspring to be successful do not cease at parturition.

Instead, its mammary gland secretes a substance with necessary growth factors to set the calf up for life.

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“She’s not just producing IgGs, she’s producing colostrum,” Mike Van Amburgh, professor at Cornell University, said at the 2018 Western Canadian Dairy Seminar in Red Deer, Alberta.

“If you stop to look at what’s going on in the glands when the cow dries off or the glands of a first-lactation animal, there are a lot of things going on there. There’s a tremendous amount of cell proliferation. The consequence of that cell proliferation is that she’s got a lot of growth factors and hormones that end up in that secretion. For years as an industry, we’ve kind of ignored that,” he said.

One example is the hormone relaxin. Reproductive physiologists working with swine discovered relaxin in the first meal stimulates growth and development of the uterus. A female piglet that receives relaxin in its first meal is likely to have a larger uterus and be more reproductively efficient than a piglet that does not.

In addition to the protein, fat and immunoglobulins (Igs) commonly looked at in first milk, colostrum also contains steroids, lactoferrin, insulin, glucagon, prolactin, growth hormone, IFG-1, leptin, TGF-alpha, cortisol and estradiol. These are all bioactive and drive metabolism, Van Amburgh said.

To show colostrum is important beyond the Igs, Van Amburgh and his research team conducted a study where calves were fed either 2 litres or 4 litres of colostrum at birth. The colostrum was highly monitored and watched for Ig and bacterial levels. Calves within each group were subdivided into an ad libitum or restricted diet.

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The restricted diet was too restricted to get an outcome, he said. However, with the high feeding rate diets, there was a significant difference in weaning weight between the high-colostrum calves and low-colostrum calves.

Weaning weight was 6 kilograms more in high-colostrum calves, and their average daily gain (ADG) was about 120 grams more. Hip height was not remarkably different.

“All calves had the same diet, same environment, same everything. We fed a 28:20 milk replacer. They had lots of protein, and a decent amount of fat,” Van Amburgh said.

Looking at the calves at 80 days old, there was still a 120-grams-per-day difference in average daily gain and the hip height was a little taller. “That implies they use their nutrients differently,” he said, noting the milk replacer intake was higher by 3.5 kilograms in the high-colostrum group as well.

“What the colostrum did, apparently, was set them up to be better animals,” Van Amburgh said.

Existing research has shown the various components in colostrum elicit biological responses. The general response to hormones and growth factors is enhanced protein synthesis, increased enzyme expression and greater gastrointestinal tract development.

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More protein synthesis means more lean tissue, whether in the gut, the liver or the muscle, he said. While increased enzyme expression results in greater digestive capacity, greater gastrointestinal tract development means more space to absorb nutrients, a better barrier to protect the calf from disease-causing organisms and a better immune system. “All of this is an outcome of the stuff that’s in colostrum,” Van Amburgh said.

In a German study, researchers compared calf response when fed colostrum or a formula product with comparable nutrients. There were seven calves in each group.

All of the calves fed colostrum were found to have higher circulating glucose, which means they had more energy to be metabolic. Four days later, those calves were still showing higher plasma glucose in response to something in the colostrum.

Van Amburgh said he suspects the response is to the insulin in colostrum. His team conducted another study where they fed a colostrum replacer to two groups of calves. For one group, they added human insulin to the prepared replacer product before feeding.

Insulin levels of the calves that received it went up, indicating it went from the digestive system into circulation. Glucose was also higher in calves fed insulin compared to those that didn’t receive it.

“The role of insulin in colostrum is to help facilitate the transport of glucose into the system,” Van Amburgh said.

“I can tell you from other empirical data that if you look at Ig transport, you see lower failure of passive transfer when you have a high amount of insulin in there,” he added. “It’s not just the glucose that’s being affected; it’s also the Igs.”

The industry tends to blame Igs for failure of passive transfer, but this researcher said it may be the result of not having enough of the “other stuff” to tell it where it needs to go.

The research shows calves that received plenty of good colostrum are still performing well post-weaning. It also shows cows are producing colostrum for more than the first day of their lactation.

Fresh cow milk has a high IGF-1 and insulin content three to four days after parturition.

“What does that mom really want to give that calf for the first three to four days?” he asked. “What she calls colostrum. When you do that, you find longer-term responses. You find better growth and better glucose.”

Van Amburgh suggested feeding colostrum for four days. For some producers, collecting colostrum for four days seems like an arduous task. That’s why he offered a less taxing process that can achieve a similar outcome.

Collect the first-milking colostrum. Feed 4 litres after birth; store and use it again for the next feeding 12 hours later. Collect the second-, third- and fourth-milking colostrum and figure out how to hold it and feed it to calves less than 4 days old.

“I’m not talking about holding four days of colostrum. I’m talking about the first two days. Most of the dairymen I know that are dry-treating those cows are not sending that milk out anyhow. You just have to figure out how to sequester it for those early life calves,” he said.

Nutrient requirements

With calves off to a good start receiving plenty of colostrum, it is important to follow through on meeting their nutrient requirements.

Van Amburgh said the industry needs to get past quantifying a calf’s diet by the number of buckets or bottles.

“What nutrients are in the bucket or bottle?” he asked. “We can’t solve our problems unless we learn how to be nutritionists.”

There is information available to aid nutritionists in calculating the nutrient supply necessary to fulfill a calf’s maintenance requirement. For example, a 40-kilogram calf needs 1.61 Mcals of metabolizable energy (ME) when it is warm outside. When the temperature drops to below freezing, the maintenance requirement of that same calf jumps to 3.3 Mcals of ME per day. “It’s a huge difference,” Van Amburgh said.

“How many of us change our intake between June and January? We change our intake; the cows change their intake; but what we don’t let the calf do is change their intake,” he continued.

Some will say calves can eat dry feed if they are still hungry, but Van Amburgh said that is an unrealistic expectation for calves less than 4 weeks old.

When calculating a calf’s nutrient requirements, a nutritionist or dairy producer needs to take the bodyweight-to-surface-area relationship into consideration. The smaller the calf, the greater the surface area compared to bodyweight, which means they lose heat faster. A study revealed the actualized maintenance requirement of a Jersey calf is 20 percent greater than a Holstein because it has more surface area to bodyweight.

The Jersey dam knows this because she makes a higher-fat milk for her offspring.

“That’s really intuitive,” he said. “The mom did that for a reason, yet we wonder why when we feed it a 20:20 milk replacer, it doesn’t do too well.”

Impact on production

A formal meta-analysis conducted by Van Amburgh and his colleagues shows increased nutrient intake that results in greater growth rate positively impacts first-lactation milk yield.

“If you feed more milk, you are two times more likely to get a positive outcome,” he said. “That’s a pretty good ratio for animal science.”

The results showed an additional 1,540 kilograms of milk produced in the first lactation for every additional kilogram of average daily gain achieved prior to weaning.

A geneticist Van Amburgh worked with said this data explains 22 percent of the variation of first-lactation milk yield, whereas genetic selection for milk only accounts for 7 percent of the variation.

Van Amburgh added there is no genetic correlation to this. “That means if you take a low genetic merit animal, you go up, and if you take a high genetic merit animal, you go up [in production],” he said.

Through biological design, the dam is trying to send information to its calf via secretion to set it up for success in life. However, human intervention can sometimes short-circuit this delivery.

In raising animals to perform at their best, it is good to know there is more to colostrum than Igs, calves have nutrient requirements beyond volume and when growth is hindered, so is future milk production.  end mark

ILLUSTRATION: Illustration by Kristen Phillips.

Karen Lee
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