Genomic selection for bTB resistance in dairy cows

An FUW seminar at the Welsh Dairy Show sheds light on genetic selection for bovine Tb resistance and asks – is this the way forward?

BOVINE TB breakdowns in dairy and beef cattle continue to be a sore point amongst farmers in Wales. Despite copious eradication programmes over the years, the disease continues to cause both emotional and financial difficulties, bringing many farming families to their knees.

October 1 2017 saw a significant shift in the Welsh Government’s bovine TB eradication programme and, as was expected, the new ‘Refreshed’ programme remains heavily focussed on cattle control measures and many of the new measures pay particular attention to chronic breakdown herds that have suffered with bovine TB for more than 18 months.

Whilst various different approaches are included in the most recent Welsh bovine TB eradication programme, the role of genetics in mitigating the effects of bovine TB has also recently come to the forefront of disease eradication discussions.

The initial research into the genetics of bTB was undertaken jointly by the University of Edinburgh, Roslin Institute and Scotland’s Rural College (SRUC) and supported by Defra and the Welsh Government.

Their work showed there is genetic variation between animals and it established the degree of heritability of bTB resistance. AHDB Dairy corroborated these findings with its research partners, SRUC and Roslin; funded the implementation of a genetic index, and embedded the TB Advantage into the national genetic evaluation service.

In addition, they have identified regions of the bovine genome associated with resistance and have shown that genomic selection for cattle with improved resistance is feasible without interfering with the current skin test for tuberculosis.

Shedding further light on the issue was AHDB’s technical manager for breeding and fertility, Andrew Dodd, who spoke at a seminar on genetic selection for bovine TB resistance, organised by the FUW, at the Welsh Dairy Show.

He said: “Dairy farmers make breeding decisions based on a number of factors and since the launch of our TB Advantage genetic index last year, they can now think about improved resistance to bovine tuberculosis. This is great news for those in high risk areas but should also be considered as a wider breeding policy by all farmers as a broader eradication strategy.”

The FUW continues to highlight that current levels of Bovine TB in Wales are in excess of what will be acceptable to other EU countries when the UK is outside the single market and the union is deeply concerned that the current disease status has the potential to be a challenging negotiation tool.

“These findings are encouraging as they could potentially allow some defense against bovine TB through selective breeding,” said FUW senior policy officer Dr Hazel Wright.

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