Most crossbred beef-dairy calves display heartier constitutions than purebreds, study finds

Many modern dairy farm operations have developed an additional revenue stream by breeding dairy cows with Black Angus beef bulls using artificial insemination to produce crossbred calves, which typically have improved meat quality and higher market value compared to purebred dairy calves. But these valuable hybrid calves often are beset with pneumonia, which was thought to limit their growth performance after they recover.

However, in a new study, a team led by Penn State researchers determined that by the age of eight months on average, the hybrid calves that recovered from pneumonia achieved similar average daily growth to calves that never had pneumonia. The team published its findings in the Journal of Dairy Science.

The research, spearheaded by Ingrid Fernandes, a graduate assistant in the Department of Animal Science, may help inform the dairies struggling to survive financially, explained study author Melissa Cantor, Penn State assistant professor of precision dairy science in the College of Agricultural Sciences.

"We've had really high inflation, of course, across the United States, but particularly in the dairy industry, where the cost of raising purebred dairy replacements has grown astronomically," Cantor said.

"Adding the beef-on-dairy hybrid sideline to their businesses has helped them, but financial constraints dictate that dairy farmers must be selective about which animals they keep. They need to be sure the practice makes sense for them economically."

In the study, the researchers reported that pneumonia observed in beef-on-dairy crosses only compromises their growth for about three weeks before they began bouncing back. Calves that were classified as having pneumonia, detected by ultrasound scans, exhibited compensatory growth when compared to their healthy peers, suggesting the illness was just a temporary setback.

For the study, the first of its kind to investigate the long-term effects of pneumonia in beef-on-dairy cattle growth, researchers evaluated if evidence of the illness identified in 143 crossbred dairy calves at weaning—when the calves change from drinking milk as their main source of nutrition to solid feed—were associated with growth performance.

Researchers assessed calf weights soon after birth, at weaning or about 14 days, post-weaning at about 21 days, and at about eight months. The researchers assessed the impact of pathogens in the calves' lungs and closely monitored the young animals' average daily growth.

They determined that lung pathogens were not associated with growth performance, and average daily growth was similar among all calves by about eight months of age. Critically, the researchers said, the calves recovered without antibiotics, which could be particularly impactful for the organic dairy industry and help reduce antimicrobial resistance in cattle.

"Our study, which aimed to understand the impact of pneumonia on growth and the potential for self-healing in calves, highlighted that beef-on-dairy crosses often recover from pneumonia without antibiotics, unlike purebred Holstein dairy calves," Cantor said.

"We think this is at least partially attributed to hybrid vigor—the phenomenon by which a progeny exhibits superiority over its parents in traits such as growth rate and productivity. This research was aimed at understanding the long-term effects of pneumonia and the economic implications of crossbreeding."