12 May 1995

Lepto jab timing must be right

LIVESTOCK producers who vaccinate cattle against Leptospirosis 10 days before or after service put fertility at risk.

That is the finding of the Department of Veterinary Clinical Science and Animal Husbandry at the University of Liverpool vet school, Leahurst, Cheshire.

Dr Richard Murray, who headed the two-year study, found that conception rates fell to 46% when cattle were vaccinated against leptospirosis in the 10 days pre- or post-service. This compared with conception rates of 58% for un-vaccinated cows.

Longer-term research has also proven for the first time that leptospirosis infection does harm fertility. In a study of fertility records for 1330 cows, conception rates in leptospirosis infected cattle were 55%; in non-infected control animals 70%.

Dr Murray maintains the greatest cost benefit for vaccination is when the infection is active and substantial improvements in fertility after vaccination have been seen.

He advises producers to ensure a full veterinary diagnosis is carried out. Care should also be taken to use the correct vaccine for the strain of Leptospirosis present in the herd.

Research was carried out in association with Professor Bill Ellis, Northern Ireland Ministry of Agriculture, Research Division, Stormont. It was funded by Lepto vaccine makers Mallinckrodt and the Association of Commonwealth Universities.