BVDV Bulk Milk Testing
This powerful assay is designed to provide producers and veterinarians with a simple “average” BVDV antibody level assessment for a population of lactating cows utilising a bulk milk tank (BMT) sample.
Seeking a tool to estimate within-herd exposure to BVDV at a reduced cost and with simpler sampling procedures than traditional serum based serological screening, the Livestock Improvement Corporation in New Zealand, validated the IDEXX HerdChek BVDV Antibody assay for use on BMT samples. The assay compares the BMT sample’s antibody level against a known positive, resulting in a “sample to positive control” or S/P ratio.
Utilising a single BMT sample, the assay has been shown capable of providing a reasonable estimate of milking herd sero-prevalence and is highly sensitive for the detection of active or very recent exposure of the milking herd to Persistently Infected (PI) animals. With a single sample, veterinarians can tailor their control strategies to most cost effectively further investigate and manage BVDV.
The BMT antibody level in a dairy herd will not fluctuate significantly unless either a PI has recently exposed the herd or there has been an addition of a group of either strongly antibody free or antibody positive animals between sampling events. We are still investigating the impact of Pestigard vaccination upon BMT antibody results, the effect is expected to be transient.
Once a milking herd’s baseline S/P ratio has been established, regular BMT sampling can provide a reference for measuring the success of control strategies and as an ongoing monitoring tool for reintroduction of the virus to the milking herd.
If an individual dairy’s S/P ratio increases significantly between samplings, it is worth investigating.