The first 24 hours: Colostrum considerations

According to Alyssa Dietrich Warner, it’s commonly recommended to feed a newborn calf a minimum of four liters of colostrum at the first feeding. Some dairy farmers choose to feed more than this. This is a way to achieve excellent transfer of passive immunity (TPI), regardless of colostrum quality. But this volume-based cookie-cutter approach is not without some controversy.

“In the last few years, I’ve come across more vets or producers who are hesitant to feed that amount of colostrum to every calf,” said Warner.

Warner is a senior calf and heifer specialist with Cargill, focusing on young animal nutrition and management for dairy farms in the Mid-Atlantic.

She cited a case from 2024 where a calf developed fatal colic from a large colostrum curd that formed in the abomasum after being tube-fed four liters at 30 minutes, followed by another two liters at six hours. This raised questions about whether such large volumes, especially when tube-fed, could cause digestive issues and calf discomfort.

There are some benefits to feeding a minimum of four liters at the first feeding. This method typically provides ample antibodies, also called immunoglobulin G (IgG). It also provides built-in security if the farm isn’t testing colostrum quality as well as adequate volume if the farm is only doing one colostrum feeding.

Rather than a volume-based colostrum feeding strategy, Warner recommended feeding 300 grams IgG within two hours of birth or a total of 400 grams IgG within 24 hours of birth. The timing is critical because the small intestine, which absorbs IgG, rapidly loses its ability to absorb it over time. By 24 hours, a calf has lost virtually all ability to absorb IgG.

Measuring colostrum quality is one way a farm can dial in how much they need to feed to achieve excellent TPI. Visible inspection of colostrum is not sufficient.

“The quality of colostrum cannot be determined by looking at the thickness or color,” Warner said. Colostrum quality also changes from season to season, making regular testing important.

On the farm, the easiest and most inexpensive way to measure colostrum quality is with an optical Brix refractometer. Colostrum is considered high quality if the Brix is 22% or greater. Warner thinks that bar could be even higher – 25% Brix is achievable, correlating to about 75 grams IgG/liter.

Another way to dial in colostrum feeding is to weigh the calf at birth and feed a volume according to calf weight. Warner cited research that showed that feeding 8.5% of birthweight may be optimal. In this research, calves received excellent quality colostrum (above 100 grams IgG/liter). For an 80-lb. calf, this equated to 3.2 liters, but smaller calves would receive proportionally less.

Some calf and heifer specialists, however, recommend feeding 10% of birthweight. This may be a better fit if colostrum quality is unknown or less than 100 grams IgG/liter. “So again, it’s not just volume and it’s not just quantity. It’s the combination,” said Warner.

Multiple feedings are another strategy to achieve the goal of 400 grams of total IgG within 24 hours of birth. In 2020, a group of industry professionals and researchers reviewed data from USDA that eventually led to new TPI recommendations.

Of the calves that achieved excellent TPI, calves that were fed multiple feedings of colostrum in the first 24 hours received an average of over 400 g IgG. Multiple feedings, therefore, can reduce the need for feeding such a large volume in the first feeding while still achieving excellent TPI goals.

Warner is often asked if tube feeding colostrum yields the same TPI as bottle feeding. Her answer is yes. She cited a study comparing IgG absorption in bottle calves vs. tube-fed calves, and she said, “We still get really good results tube feeding calves.” She did caution that tube feeding could have other impacts, including esophageal injury and aspiration pneumonia.

Some farms may opt to use colostrum replacer. Warner said to be sure to read labels carefully. Many farms make the mistake of underfeeding colostrum replacer because they believe that one packet is enough. Many packets only contain 100 grams of IgG or less, however.

To control colostrum replacer costs, Warner said, “Probably the best option for the calf and for your budget is to use a combination of colostrum replacer and maternal colostrum. So the way you would do this is feed about 50 grams IgG worth of colostrum replacer with lower quality colostrum – colostrum that tests below 22% Brix.”

Ultimately, Warner believes that colostrum feeding protocols in the first 24 hours should be farm specific. Labor capabilities and patience levels, labor availability and employee experience and trustworthiness to make judgement calls will all impact colostrum feeding.

She said, “Every farm is sort of unique and every farm has a different ability to execute different things. So you can have a perfect protocol on paper, but that doesn’t mean it’s going to get done correctly.”

by Sonja Heyck-Merlin