Study links subclinical BRD with slower growth in dairy heifers

A new retrospective study in Frontiers in Veterinary Science links subclinical bovine respiratory disease at weaning with poorer growth and distinct nasal and fecal microbiota patterns in dairy replacement heifers. The study followed Holstein-Friesian and Jersey heifers and found that calves classified as healthy were heavier and had higher average daily gain than peers with subclinical BRD, while microbiota differences were driven largely by low-abundance bacterial taxa rather than broad shifts in dominant organisms. The work adds to a growing body of research suggesting that respiratory disease that goes unnoticed clinically can still leave measurable production and microbial signatures. (holoruminant.eu)

Why it matters: For veterinary professionals working with dairy herds, the findings reinforce that “silent” BRD may carry meaningful performance costs even when calves don’t show obvious illness. That matters because BRD remains a leading health challenge in young cattle, and prior research has shown links between lung lesions, altered respiratory microbiome diversity, and reduced live-weight gain. In practice, the study supports closer use of tools such as thoracic ultrasound, structured calf respiratory scoring, and earlier herd-level prevention strategies, especially around the pre-weaning and weaning periods. (frontiersin.org)

What to watch: Watch for follow-up work testing whether these microbiota signatures can help identify at-risk calves earlier, or guide prevention strategies before subclinical lung disease affects long-term heifer performance. (teagasc.ie)