Why dairy calves need more colostrum

Glacier FarmMedia – Researchers are recommending another jump in how much colostrum a dairy calf receives per day in its first meal.

Michael Steele, a professor in the Department of Animal Biosciences, told the recent Dairy at Guelph research day that they’re now discussing ensuring calves receive 300 grams of immunoglobulin G (IgG) in their first 12 hours.

Why it matters: Calves are born with naïve immune systems, and colostrum is rich in antibodies to protect the calf until its immune system develops.

“On farms, we’re just not feeding enough colostrum,” Steele says.

Twenty years ago the goal was 100 grams of IgG, 10 years ago, he says it was 200 grams, but he now says the discussion is about how to get calves 300 grams.

Beef calves that stay with their dams ingest from 250 to 500 grams of IgG.

The quality of colostrum is also important and researchers are looking at how to boost the quality of colostrum to make sure it hits the needed level of IgG.

Push the levels of IgG per litre above 50 grams if possible, even to as high as 70, he says.

“I think we have cows that can do this.”

Steele also recommends increasing the volume of colostrum in the first 12 hours of life from 10 per cent of body weight to 12 per cent in two meals – eight per cent in the first meal and four per cent in the second.

How is colostrum made in a cow?

There’s much that’s not yet known about how colostrum is formed and what influences its quality.

It can be modified by parity, season, sex of calf, dry per length and how much milk was produced in the cow’s previous lactation.

“We don’t understand enough about colostrogenesis,” says Steele.

Some of his students have tried to fill in some of those gaps.

Amanda Fischer-Tlustos other masters and Phd students at the University of Guelph have looked extensively at the physiological factors that affect colostrum production. They did biopsies and ultrasounds to look at mammary systems and blood flow.

“We have studies showing how dietary interventions or different management strategies can impact it, but we’re really just guessing about the mechanisms,” says Steele.

They found that IgG production increases up to a week before a cow gives birth. However, other bioactive compounds increase in the week before the cow has her calf, which means there are multiple areas to be influenced to change colostrum quality.

The researchers are also looking at molecular pathways and how they affect colostrum.

What makes successful colostrum management?

• Calves fed within an hour of birth
• Colostrum with more than 22 Brix measurement and 50 grams per litre of IgG
• Clean colostrum
• At least 10 per cent of body weight in colostrum is consumed in the first 12 hours of life

– This article was originally published in the December 2, 2025 issue of Farmtario.