Proper nutrition and gut health is key to raising healthy calves. Their nutrition from birth to postweaning can dictate their future production, fertility, and mortality. Different dietary recommendations are made for calves as they progress through the various stages of life.

Birth to preweaning

In the December 2024 Hoard’s Dairyman monthly webinar, “New developments in calf nutrition: Challenging the dogma,” Michael Steele, a professor at the University of Guelph, discussed the importance of feeding high-quality colostrum during the first 12 hours of a calf’s life. Steele stated that one should consider feeding more colostrum within the first 12 hours. Currently, the standard recommendation is to feed roughly 10% of the calf’s body weight in colostrum. Depending on the calf, Steele advised to feed between 12% and 15% of body weight. In addition, he discussed the importance of being proactive in administering the calf’s first feeding of colostrum. Delays in feeding can cause the gut microbiota, which plays a crucial role in developing a healthy immune system, to be less effective if fed outside the 6-to-12-hour range.

During preweaning, calves are highly prone to disease and most scour outbreaks occur in this stage. Steele’s research shows that sick calves treated with a standard antibiotic, like neomycin, experienced long-term effects like lower conception rates and milk production in their first lactation, decreased fertility, and higher culling rates. His data showed that treatment potentially alters the calf’s metabolism, improving gut permeability. Alternatively, Steele recommended colostrum therapy as a treatment for scours. “Mixing a 50/50 milk-colostrum mix resolved diarrhea in one test group of calves,” said Steele. “And we saw a greater average daily gain and body weight response at 42 and 56 days as a result of this treatment.”

Weaning and postweaning

Determining when to wean is crucial. “The number one factor to remember is that weaning later is always better,” said Steele. Calves under 8 weeks of age should not be weaned, especially if they are receiving high levels of milk. The timing of weaning should be decided based on the calf's starter feed intake. Steele highlighted that “some calves at 48 days are not eating starter, yet they are getting weaned.” Incorporation of starter feeds and timing of weaning should be done on an individual calf basis.

Steele noted that postweaning has not been fully studied. He explained, “We need to integrate pre- and postweaning planes of nutrition with lifetime performance.” Calves become extremely efficient a few months after weaning, so he recommended feeding a high-quality starter and slowly incorporating a grower feed. As forage intake increases, their diet should consist mainly of forage by 6 months.