How to Choose a Bovine Colostrum Supplement: A Dairy Farmer’s Checklis

As a seventh-generation dairy farmer, here are the seven questions I’d ask any colostrum company, from where it came from and whether the calf was fed first to how it was processed and what the finished powder actually tests at.

Written by Founder: Rob Diepersloot

If I were buying colostrum for my own family, I wouldn’t just look at the marketing on the front of the jar.

I’d want to know where it came from (US vs foreign), how it was collected, what was removed, how it was processed, and what the finished product was actually tested for.

I’m a seventh-generation dairy farmer and the founder of a colostrum company, so I come at those questions from both sides. I know the work that happens before colostrum becomes an ingredient. I also know how much information can get squeezed into a few impressive-sounding words on a label.

Here are seven questions I’d ask any colostrum company, including WonderCow.

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1. Where did the colostrum actually come from?

For me, the quality story starts at the farm.

I want to know where the dairy farms are, how the animals are cared for, and whether the company can trace its ingredient through collection, processing, and the finished product.

If a brand says its colostrum comes from U.S. dairy farms, ask how that sourcing is documented. A country-of-origin statement is useful information, but I would still want answers about animal care, handling, and testing.

The same goes for “grass-fed.” Ask what the company means by that term. What do the cows eat? Is supplemental feed allowed? How is the claim verified?

You don’t need to know every farmer personally. But the company selling you the product should understand its own supply chain well enough to explain it.

2. Was the calf taken care of first?

Before I worry about the supplement, I want to know that the calf got what she needed first.

Newborn calves depend on colostrum for early nutrition and antibodies. Getting enough high-quality colostrum promptly (within 1-2 hours) after birth matters enormously. ^[1]

Here’s what that looks like on our farm.

We collect colostrum with a milking machine, then use a Brix refractometer to screen its quality on the farm. Our threshold for the calf-feeding supply is a reading above 22% Brix to guarantee high quality colostrum both for the calf and for our supplements.

We feed the calf one gallon first, followed by two quarts every eight hours until she transitions to whole milk.

When a cow produces more than her calf can consume, we freeze the surplus for future calves. That reserve matters because another cow may not produce enough.

Only after the calves are fed and our reserve is full do we direct the additional surplus toward supplements.

We call that the “extra extra.”

That’s the explanation I’d want behind a calf-first promise: what happens first, what gets held in reserve, and when colostrum becomes available for other uses.

3. When was it collected—and how was its quality measured?

Colostrum changes as a cow transitions toward producing mature milk. Collection timing gives you useful context, but I wouldn’t use a milking number as my entire definition of quality. ^[2]

WonderCow’s supply is generally first-milking colostrum. Second-milking colostrum can qualify when it meets our high-quality requirements.

Our approach is to qualify the colostrum by quality rather than accept or reject it solely because of the milking number.

That doesn’t make timing irrelevant. It means the next question matters: “What do you measure to decide whether this colostrum qualifies?”

Also remember that testing fresh colostrum on the farm and testing a finished powder answer different questions. A Brix reading helps us screen fresh colostrum for calf feeding. It does not replace laboratory testing of the supplement you buy.

4. Is it whole—or was part of it removed?

I chose whole colostrum because my starting point is to retain its naturally occurring components unless there is a compelling reason to remove them.

Colostrum contains proteins, carbohydrates, fats, and many other constituents. My interest goes beyond a single headline ingredient or percentage. ^[2]

At WonderCow, we choose to retain the naturally occurring fat rather than defat the colostrum. To me, keeping those components together fits our whole-food philosophy.

That is the reasoning behind our choice.

For a shopper, the practical question is straightforward: “What was removed, concentrated, or added—and why?”

A company should be able to explain those decisions. If it calls its product “whole,” it should also explain what that means for the composition of its finished powder.

5. How was it processed?

I understand why people respond to words like “cold processed” or “low temperature.” They want reassurance that the ingredient was handled carefully.

But processing deserves more explanation than “heat is bad.”

Time, temperature, and the particular component being measured all matter. Researchers studying colostrum processing have found that different treatments affect its proteins and their measured activities differently. ^[3]

I want a process that addresses food safety while preserving the characteristics the company says matter.

So I would ask: “What does your processing claim mean, and what evidence supports it?”

If a company says its process preserves IgG, ask whether it measures IgG in the finished powder. If it makes a broader claim about biological activity, ask what activity was tested.

Measuring how much of a component is present is useful. Demonstrating that component’s activity is a different question. Demonstrating a health benefit in people is another.

A good explanation should keep those distinctions clear.

6. What does the finished powder actually test at?

Sourcing and processing tell you how the product was made. Testing helps you evaluate the result.

I’d ask about identity, composition, IgG, microbiological safety, contaminants, and consistency between batches. If the product is described as whole colostrum, I’d ask how its composition supports that description.

For contaminants specifically, WonderCow tests every finished-powder batch for heavy metals, BPA, BPS, BPF, pesticides, glyphosate, AMPA, phthalates, and PFAS. Customers can access those reports.

Those are questions I believe consumers deserve to ask across this category.

But “tested” should start a conversation, not end one.

Which substances were included in the panel? What were the results? Which batch does the report cover? What could the method detect, and what acceptance limits were used?

“Not detected” means a substance was not detected above the method’s detection limit. It does not mean a laboratory has established absolute zero.

You don’t need to interpret every laboratory detail yourself. You should be able to get a report and an understandable explanation of it.

And remember: contaminant testing addresses particular safety questions. It does not, by itself, prove that a supplement delivers a health benefit.

7. Can the company explain its claims?

“Grass-fed.” “First milking.” “Bioactive.” “Whole.” “Cold processed.” “Clinically backed.”

Each phrase should come with an explanation.

If a company advertises an IgG percentage, ask whether that number describes the finished product and how it was measured.

If it says “clinically backed,” ask which study it means. Was the research conducted on that product, at the suggested serving size, in people relevant to the claim?

If it says “whole,” ask what was retained and what, if anything, was removed.

For me, willingness to answer is an important signal of accountability. It still needs to be backed by sound practices and evidence.

I would rather hear a clear explanation with appropriate limits than a sweeping promise that falls apart under a follow-up question.