Thanks to the use of new ultrasound technology, there’s now solid evidence out of the University of Guelph indicating the level of non-clinical lung infections among dairy calves is on par with what has already been seen in the beef sector.
Why it matters: A member of the team involved in the dairy calf study, Dr. Stephen Leblanc of the university’s Department of Population Medicine, says the recent research shows dairy producers can use thoracic ultrasonography to prevent pneumonia or other respiratory ailments.
“It’s a practical, farm-usable technique,” Leblanc said. “It only takes about two minutes per calf once practiced. A couple of workshops have trained perhaps 20 to 30 vets in Ontario in the technique, which uses the same ultrasound machine as is used for pregnancy diagnosis.”
Leblanc was contacted following the publication of an article entitled “The effect of lung consolidation, as determined by ultrasonography, on first-lactation milk production in Holstein dairy calves” in the June, 2018 edition of the Journal of Dairy Science. The paper was a follow-up to a larger body of work by Dr. Teri Ollivett, who is now a professor in the University of Wisconsin-Madison’s School of Veterinary Medicine but who completed her PhD in Population Medicine at Guelph.
Information in the article is drawn from Ollivett’s study of 215 female calves from three different southwestern Ontario dairy herds. Weekly ultrasounds to identify lung lesions were carried out on the calves during the first eight weeks of life. The calves were then tracked through pregnancy, first calving, and first lactation milk production.
According to the journal article, “the presence of lung consolidation, at least once in the first eight weeks of life, did not influence age to first calving, but did result in a 525 kg … decrease in first-lactation 305-day milk production.”
Some of these lung disease cases, Leblanc stresses, would have been noticed and treated by the farmer even without ultrasound. “Roughly 20 per cent of dairy calves may be treated for respiratory disease in the first two months of life based on visible clinical signs (such as) dullness, coughing, or fever.” Ollivett’s recent work, though, suggests lung ultrasound represents a potential for early identification of 20 to 30 per cent more calves with lung lesions but no visible signs of disease.
“This is in the ballpark of what is seen in feedlot steers for clinical pneumonia versus lung lesions present at slaughter,” Leblanc said, adding it has already been established that there’s an “association” between the presence of those lesions and worse gain in the beef sector.
He added there are active research projects in Wisconsin and Quebec aiming to determine the degree of benefit of treating sub-clinical lung lesions once they’ve been identified by ultrasound. But he says a very important message from Ollivett’s work is that future milk production can be affected by early-life infections. (Previous work by Amy Stanton at University of Guelph showed that only 65 to 75 per cent of calves experiencing clinical early-life respiratory disease remained on the farm through the end of first lactation, compared to 85 per cent for those that weren’t affected.) Farmers help prevent disease by improving ventilation in calf-rearing facilities, ensuring calves get enough to eat and training employees to detect and treat clinical diseases as soon as possible.
He predicts that thoracic ultrasonography will eventually join this list of practices for preventing lung disease. The technology, he said, “has really just been developed in the last 10 years. We’re still learning about how to interpret and use the data.” But he has been told of a few practitioners at the Kirkton Vet Clinic who have tried it on-farm, and encourages dairy producers to ask their own vet about the technology’s potential.