Dairy Herd - Vaccination
The Importance of Vaccination in the Dairy Herd
The aim of most progressive dairy practices is towards preventative rather than reactive medicine. This improves profit margins for the vet and client. Vaccination and herd health planning are critical to achieving this aim especially when risk factors for infectious disease are high, e.g. where biosecurity is poor.
Prevention of disease is always preferable to treating clinically affected animals, both in terms of economics and animal health and welfare. Avoiding conditions such as scour and pneumonia is integral to maintaining a productive and healthy herd. Diseases not only result in acute losses during the initial outbreak, but also future poor performance due to chronic changes, for example pulmonary fibrosis. It is estimated that if replacement heifers are clinically affected with pneumonia in the first 3 months of life then overall milk yield can drop by 2.2% and that there can be a 2 week delay to first service in comparison to their cohorts (1).
Fertility is a key factor in determining profitability. A recent study in Northern Ireland has estimated that the cost of a calving index exceeding 365 days is between £1.50 and £3 per day depending on average milk yield (2). Vaccination can help to minimise this cost by reducing the prevalence of infectious infertility, caused by IBR, BVD and Leptospirosis.
BVD has a negative affect on fertility in terms of conception rates and abortion. The cusum above is an example of the effects of BVD on a dairy farm in Cheshire, conception rates significantly dropped when the protection offered by the vaccine expired. The cost of this drop in conception rate was significantly greater than the cost of the BVD vaccination.
Vaccination of cattle against Leptospirosis in clinically affected herds can increase the overall conception rate by 20% (3). Another study has shown that cattle exposed to Leptospirosis had a conception to first service rate of 30%, whilst 46% of vaccinated animals conceived at their first service (4).
Leptospirosis, Dermatophytosis, Salmonella dublin and S.typhimurium are zoonotic pathogens that we should consider when vaccinating dairy cattle. The most important of which is Leptospirosis, which can cause severe and prolonged flu-like symptoms, meningitis, renal failure and death in man. Vaccination will greatly reduce the shedding of the organism in bovine urine, and therefore reduce the human health risk.
Vaccination should be integrated into a productive and relevant herd health plan. Vaccines do not claim 100% efficiency, and in the face of overwhelming challenge breakdowns can occur. It is also vital to stress that vaccines should be stored and administered according to data sheet instructions to ensure animals are adequately protected. Farmers should also be made aware that the beneficial effects of vaccination may not be clinically obvious immediately.