BVD incidence is 10pc heritable

Irish BVD incidence is 10pc heritable. This is according to the Irish Cattle Breeding Federation, who had a beef and dairy industry think-in with Teagasc last week.

Teagasc 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.

According to an update from the ICBF out yesterday, it said: “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 per cent, which the ICBF said is “quite remarkable given that other health and disease related traits, for example female fertility and mastitis incidence have heritability estimates of only 2-3 per cent”.

“The degree of genetic variation was reflected in the large phenotypic variation observed [See ICBF graph below], which indicated that some bulls produced calves with almost no infection, whilst others produced calves with up to 20 per cent 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,” it added.

Whilst some might argue the exercise was largely academic, the ICBF said it is currently undertaking an eradication program for BVD virus-based on a testing and culling policy. And 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 programmes, the federation stated in its August update.

” This view was confirmed by subsequent analysis presented by Teagasc in which experts indicated heritability estimates (based on Irish data) for incidences of TB, IBR, and Johnne’s of 18 per cent, 28 per cent and 10 per cent respectively.”

The ICBF is 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 ICBF expects it is, this suggests that in the future ICBF should be able to breed animals that are more resistant or resilient to infection. This is states 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 its website here.

The ICBF can be contacted on 1850 600 900.