Sandra Godden, D.V.M., of the University of Minnesota used this seesaw illustration during an I-29 Moo University webinar to highlight just how critical it is to do everything we can to keep calves on the right side of being healthy. Minimizing disease triggers for calves covers many of the steps we take elsewhere on the farm for older animals — following sanitation protocols and providing proper ventilation and bedding.

An animal of any age can have its immunity against disease boosted with vaccination, proper nutrition, and limiting stress. These factors certainly play a crucial role in calf health, but for the youngest members of our herds, we also have access to the not-so-secret weapon of colostrum to keep things balanced.

What can be achieved?

Colostrum, of course, is important for its role in providing antibodies to a calf as it is still developing its own immunity early in life. Achieving successful passive transfer of these immune-boosting components has been shown to reduce the incidence of disease and mortality in the short, medium, and long term, Godden said. It also contributes to better growth, feed efficiency, and milk yield in the first and second lactations. For all of these reasons, a 2016 meta-analysis of colostrum research estimated the cost of failure of passive transfer to be at least $70.

But there’s more value to this milk, too. “Colostrum isn’t only about those antibodies,” Godden discussed. Colostrum also contains nonspecific immune factors, hormones, growth factors, and more nutrients that make a difference to the young calf’s microbiome and growing body. It typically has a solids content of at least 24%, she noted.

To take advantage of these benefits, begin by setting goals for your colostrum program. Since there is no direct way to measure immunoglobulin (IgG) absorption on the farm, Godden explained that we monitor it by proxy by measuring serum total protein. To achieve successful passive transfer, Godden said we want to reach a serum IgG concentration of at least 10 grams per liter. This correlates to a serum total protein level of 5.2 grams per deciliter (dL). The most recent industry target is for at least 90% of calves to reach this benchmark. Research has shown that even higher levels further reduce the risk of disease and death, she continued. Aim for at least 70% of calves to achieve serum total protein over 5.8 grams per dL and 40% to reach 6.2 grams per dL.

There will be variation in passive transfer between calves, so Godden advised tracking serum total protein on a herd level instead of individual calves. Ideally, this would be done all the time, but it should at least be done if a farm is investigating an outbreak of calf disease.

Getting there

Reaching those goals depends on four main factors: quality, quantity, quickness, and cleanliness of the colostrum provided.

We consider high-quality colostrum to have an IgG concentration of at least 50 grams per liter, Godden said. The most recent National Animal Heath Monitoring System survey found that, on average, calves receive about 74 grams per liter of IgG. However, roughly one-quarter of the samples still tested as poor quality.

Colostrum quality is measured on the farm with a colostrometer, which reads a liquid’s specific gravity that is correlated with IgG, or a Brix refractometer. Again, Godden recommended evaluating these readings on a herd level; aim for 90% of cows to be producing colostrum with a Brix reading of at least 22%. If your herd is not meeting this goal, review how cows are cared for. Colostrum quality can vary widely based on some factors we can’t control, like parity, but others we can impact. These include dry cow vaccination, nutrition, heat stress, dry period length, and the interval from calving to colostrum harvest. Of these, Godden highlighted that research shows cows move antibodies into colostrum when they received dry cow vaccinations and that quality is reduced when cows are dry for less than 21 days.

Calves must also receive enough high-quality colostrum. Godden said to aim for 8.5% to 10% of the calf’s body weight, but pure quantity is not the only consideration. “It’s really not a volume goal, it’s a dose goal,” she explained. That’s a function of quantity multiplied by average quality. Make your main benchmark delivering 150 to 200 grams of IgG, she said.

That must be delivered quickly to maximize the immunity the calf can utilize. The efficiency of IgG absorption is about 30% at birth and down to 10% by 12 hours of age, Godden said. By 24 hours old, it is near zero. “That’s our window of opportunity,” she asserted.

Feed colostrum as early as possible, ideally within one to two hours of birth. If that’s not possible, Godden said to get 90% of calves fed within six to eight hours.

Following these recommendations does little good, and likely does harm, if the colostrum fed is loaded with pathogens that negate its immune-boosting properties. Higher bacteria counts are also correlated with lower serum IgG levels, Godden added. Aim for fresh colostrum to have a bacteria load of less than 100,000 colony forming units (CFU) per milliliter, she said. If it’s pasteurized, that number should be under 20,000.

If your colostrum is not in line with those numbers, look at how colostrum is harvested. Is the udder cleaned and all handling equipment sanitized like it would be if you were milking a lactating cow? Also, do not pool raw colostrum, and avoid bacteria proliferation by feeding it as soon as possible. If colostrum must be refrigerated, keep it at 40°F for no more than 48 hours. Otherwise, freeze it at -4°F for up to six months. Ensure chilling occurs rapidly, and prevent frozen colostrum from going through multiple freeze-thaw cycles that can denature antibodies.

Dairy farmers have significantly reduced the number of calves that don’t achieve passive transfer in the last few decades. But Godden encouraged that there are still improvements that can be made, and they will make a difference even if it takes 10 more minutes to do a good job of feeding colostrum.

“You are going to be paid back many times over,” Godden affirmed.