Have you ever wondered why only a handful of your cows became TB reactors during a herd breakdown when all cows were managed the same?

Answer; Genetic Resistance

Genetic resistance is a measure of an animal’s ability to fight off infection due to its genetic makeup. This means that farmers can breed cattle that are less likely to become TB reactors.

How can I breed for a healthier herd?

Farmers are advised to select cows and bulls for breeding that have the highest overall index as well as the lowest breeding value for TB resistance.

Where can I view the TB information on my animals?

To view the TB breeding values for individual animals in your heard, simply look at their health sub-index.

What figure should I use?

To improve TB resistance, herds should aim to use bulls with a PTA (breeding value) of less than 8%. For more rapid improvement, use bulls of less than 6.5%.

High EBI does not guarantee favourable genetic resistance to TB. Bull A above has a high EBI, but ranks as one of the worst bulls available for TB resistance. Bull B has a similar (but lower EBI) which produces progeny with more favourable genetic resistance to TB.


Select high EBI bulls with a lower TB breeding value (PTA) to improve genetic resistance in your herd.

For a more detailed explanation genetic resistance to TB, click here.