A guide to the TB Advantage genetic index

Launched in January 2016, TB Advantage, published by AHDB Dairy, is a genetic index for use by farmers to assist in breeding cows which have a heightened resistance to bovine tuberculosis/  TB (bTB).

Scotland’s Rural College, Roslin Institute and the University of Edinburgh jointly undertook wide-ranging research into the genetics of bTB, supported by the Welsh government and Defra, in order to create this TB management index. This is the first index of its kind in the world using data showing genetic variations between animals.

What does this index tell us?

Currently, the TB Advantage index is only available for Holstein cows as the research looked at 650,000 of this breed with data recorded by the Animal and Plant Health Agency (APHA) relating to bTB. It has enabled the establishment of breeding patterns to identify bloodlines with more resistance to the disease. Whilst this is an excellent tool for farmers to use in selecting breeding stock, it needs to be read in conjunction with other elements of the UK’s strategy for the eradication of bTB in the longer term.

Using the TB Advantage index

This index should be used in conjunction with other relevant breeding indexes in order to identify a breeding plan which is suitable for the herd. This ensures that a herd’s strengths are maintained and any weaknesses kept to a minimum. If a herd is located in or close to an affected area, it may be that the TB index should be weighted more heavily. And as with other indexes, its range is from -3 to +3, with the positive range values being preferable when selecting a sire.

Selecting a bull which scored positively on the index should have no detrimental effects on other traits, as its relationship with the Profit Lifetime Index and also with the Spring Calving Index is favourable. It will, of course, be up to the breeder to consider the TB Advantage index in conjunction with other genetic indexes, to ensure that other genetic weaknesses are not introduced into the bloodline which will be unfavourable for that particular herd. The reliability range for the index is between 20 percent and 99 percent. with 65 percent being an average reliability score for bulls with a number of daughters.

For further comprehensive reading about TB Advantage and up to the minute information about TB in general, its management and control, TB Hub provides a comprehensive guide.

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