Nutritional regulation of gastrointestinal function in calves pre-weaning – Dr. Michael Steele, University of Alberta

By Brittany Olson, contributing writer
Colostrum, with its concentrations of immunoglobulin (IgG) proteins, dam-specific antibodies, and growth hormones, plays a key role in getting a calf started on the road to being a productive cow in the future.  During his general session at Vita Plus Calf Summit, Dr. Michael Steele, assistant professor at the University of Alberta, explained how providing quality colostrum early in a calf’s life can help it take in nutrition and repel pathogens.

Steele cited a 2007 study that showed if a calf isn’t given colostrum quickly enough, its path to being a productive member of the milking herd may be impeded.  According to the study, 19 percent of calves fail passive transfer of immunoglobulins (IgG), and 24 percent of calves have scours in the first month of life.

He said 10 percent of calf mortality and 50 percent of calf morbidity is related to diarrhea.  Additionally, treating calves with antibiotics before weaning has been linked to decreased lifetime milk production.

On the other hand, Steele noted how feeding quality colostrum early in life can translate to greater production later.  According to a 2012 Cornell University study, one additional pound of average daily gain (ADG) before weaning was linked to an additional 1,540 pounds of milk produced in first lactation.

“There is not one paper showing that increased average daily gain has a negative impact on future milk,” Steele said.

Even though the gut has commonly been thought to “close” itself off to passive transfer after the first 24 hours of life, it remains highly penetrable for the first few days after birth.  Steele said that is because passive transfer is thought to be receptor mediated and highly regulated, therefore, the calf’s gut can potentially stay open longer.

Because passive transfer is negatively impacted after even a six-hour delay in feeding colostrum, Steele recommended feeding frozen colostrum or a quality colostrum replacer if time was running out or the cow didn’t produce enough for her calf.

“If you’re strapped for time, tube feed colostrum,” Steele said. “With tube feeding the milk hits the rumen first and then the abomasum, while bottle feeding allows the milk to hit the abomasum first.  There is zero difference in IgG transfer between the two.”

The first two weeks of life are extremely critical to gut health.  Therefore, Steele recommends calves stay on transition milk longer instead of switching to regular milk or milk replacer after the first feeding of colostrum.  Steele said, for at least the first five to six milkings post-calving, cows are still producing insulin and growth hormone in their milk that calves need.

Calves that stay on transition milk longer have shown more developed villi than calves that switch immediately.  Transition milk also has probiotics, such as bifidobacteria and Lactobacillus, that aid in digestion and the development of tissues, like mucosa in the colon.  It also contains oligosaccharides, which serve as a food source for the probiotics, according to Steele.

After transition milk runs out and the calf is switched to either whole milk or milk replacer, calf managers must decide what works best for their farm.  Calves on higher planes of nutrition may see ADGs of up to 2.2 pounds per day, with calves on lower planes potentially seeing just under 2 pounds per day.

Steele said larger meals can cause blood glucose spikes and slower abomasal emptying, while smaller, more frequent meals throughout the day, as offered by an autofeeder system, mimic nursing patterns in nature.  However, calves in twice-a-day feeding schemes showed no difference to glucose tolerance.

“Calves on lower planes can catch up quickly with starter intake,” said Steele.

Growing calves from the inside out with minimal environmental stress gets the ball rolling for them to become healthy and productive dairy cows once they enter the milking string.  Steele concluded by giving attendees the following questions to consider at feeding time:

• Are calves aggressive at milk feeding time?
• Is their manure firm and consistent?
• Are calves ruminating and achieving starter grain intake benchmarks?
• Are they achieving targeted growth rates?