BVD Incidence is 10% Heritable

“Some bulls had 20% of their calves infected with BVD, whilst other bulls had 0% calves infected with BVD. Why is this?” This was the question posed by Dr Donagh Berry, Teagasc, at last week’s ICBF beef and dairy industry meeting in the Killeshin Hotel, Portlaoise.

Dr Berry was presenting data from the first year of National BVD eradication scheme, where some 1.86 million individual BVD sample records have been collected to date, by Animal Health Ireland (AHI) and the individual test laboratories. All of the records are stored in the ICBF database.

The analysis was restricted to herds that had a minimum of one PI (Persistently Infected) calf in the herd and to other cows (and calves) that were borne at the same time as the infected animal(s). This was to ensure that contemporary animals in the herd had maximum opportunity for equal exposure to the BVD virus. The resultant analysis was therefore based on 54,234 animals in 2,534 herds.

Genetic analysis of the data indicated a heritability for BVD incidence of 10%, which is quite remarkable given that other health and disease related traits, e.g., female fertility and mastitis incidence have heritability estimates of only 2-3%. The degree of genetic variation was reflected in the large phenotypic variation observed (See graph) which indicated that some bulls produced calves with almost no infection, whilst others produced calves with up to 20% infection. These results were based on bulls that had a minimum of 50 progeny in 10 herds, thereby confirming the strong genetic basis for the trait.

Whilst some might argue that the exercise was largely academic (we are currently undertaking an eradication program for BVD virus based on a testing and culling policy), the analysis does confirm that health and disease traits are heritable and on that basis, genetics should become a strong part of future health and disease programs. This view was confirmed by subsequent analysis presented by Donagh in which he indicated heritability estimates (based on Irish data) for incidences of TB, IBR, and Johnne’s of 18%, 28% and 10% respectively. We are currently looking at the inter-relationships between the traits, as the view is that these traits are all strongly correlated. If this is the case (and we expect it is), this suggests that, in the future, we should be able to breed animals that are more resistant (or resilient) to infection, which would be a major step forward for our dairy and beef cattle industries.

A full copy of the slides from last week’s ICBF industry meetings are posted on the Presentations Page. If you have any questions, please do not hesitate to contact us on 1850 600 900.

Close Menu