Preventing respiratory disease early in calfhood could have long-term beneficial effects on the health and performance of dairy heifers, according to a research study recently published in the Journal of Dairy Science. The study, conducted by Amy Stanton of the University of Wisconsin-Madison dairy science department, examined the long-term performance of nearly 1,400 Holstein heifers from seven commercial dairies that were reared post-weaning at a single commercial heifer-raising facility in western New York.
Heifers were enrolled in the study upon weaning and removal from individual hutches or nursery barns and transfer to group housing at the heifer facility. Average age at the time of this event was 56 days. At that time, one of two prophylactic treatments for respiratory disease was administered – either subcutaneous injection of 200 mg of tulathromycin (Draxxin Injectable Solution) or intramuscular injection of 1,000 mg of oxytetracycline (Biomycin 200 Injection).
All animals were monitored for bovine respiratory disease for the next 60 days following treatment and movement to group housing. Animals that experienced the disease were classified as the “BRD60” group. Regardless of disease incidence, all heifers were evaluated later for: growth of heifers until breeding age; age at first calving; incidence of dystocia at first calving; milk production; mortality before first calving; and mortality before 120 days in milk. Results included:
- Heifers treated with tulathromycin were half as likely to experience BRD60 than the heifers treated with oxytetracycline.
- Treatment with tulathromycin was associated with higher growth rates for approximately four months after treatment in calves without prior BRD in the preweaning stage.
- 63% of tetracycline heifers in the BRD60 group survived to first lactation, while 74% of the tulathromycin group in BRD60 did so.
- For heifers with no respiratory disease in the 60 days following movement to group housing, 84% survived to first lactation, regardless of treatment.
- The median age at first calving without BRD60 was 702 days, compared to 716 days for the BRD60 group.
- Heifers with BRD60 were 1.5 times more likely to have a calving ease score of > 2 (scale of 1-5, indicating slight problem calving) at first calving compared to non-BRD60 heifers.
- BRD 60 tended to decrease first-test milk weight by about three pounds per day, but had no effect on projected 305-day milk production.
Stanton concludes that prophylactic treatment with tulathromycin at movement to group housing may have a beneficial role in preventing respiratory disease and reducing some of its long-term effects.