Bovine respiratory disease can sit in a calf's lungs without a cough, a runny nose or a dropped ear, research from the Agri-Food and Biosciences Institute (AFBI) in Northern Ireland has shown. Using the same portable ultrasound scanner a vet carries for pregnancy checks, the AFBI Hillsborough team found lung damage in calves that passed every visual health check.

The study, funded by Feed For Growth (Volac Milk Replacers Ltd), was run inside a wider calf-nutrition trial. A total of 108 calves were offered different diets to 13 weeks of age, with feed intake recorded daily, live weight fortnightly and visual checks for respiratory disease three times a week. Each calf was also lung-scanned at five to six weeks and again at 12 to 13 weeks.

At the first scan most lungs were healthy: 5.6 per cent (six calves) showed moderate pneumonia and none had severe damage, and only two of the six had shown any visible sign of illness. By the second scan the share with moderate pneumonia had risen to 14.8 per cent (16 calves), and not one of the 16 looked obviously ill.

Respiratory disease, or pneumonia, is one of the leading causes of ill health and death in calves and costs the UK cattle industry between £60 million and £80 million a year, AFBI said. It is caused by bacteria or viruses and made worse by poor ventilation, cold and damp housing, too little good colostrum at birth, and stressful events such as disbudding, mixing and weaning.

"The results of this study show that BRD can be present in visibly healthy calves, putting them at risk of reduced performance and efficiency throughout their lifetime," said AFBI researcher Dr Gillian Scoley. Scanning, she added, lets individual calves be treated according to actual disease severity rather than blanket-treating whole groups, which supports responsible use of medicines.

Dr Jessica Cooke of Feed For Growth said the trial team wanted to see whether different planes of nutrition affected lung health, and scanning allowed an objective look beyond clinical signs. Iain Smith of Lisburn Veterinary Clinic, who carried out the scans, said the technique also shows how well a vaccination programme is protecting calves.

AFBI listed the signs to watch for during high-risk periods: a drop in milk intake, flicking or drooping ears, eye or nasal discharge, coughing, a temperature above 39.5°C, dullness, and laboured breathing.

Reported by Kathleen O'Sullivan for Agriland.

Source: Agriland