Did you know you can now breed against TB and liver fluke?

New research means that you can now breed dairy and beef animals that have a greater resistance to a tuberculosis (TB) and liver fluke infection.

You may wonder why only some animals in your herd are TB reactors when in truth, all the animals should have been exposed to TB. The answer to this is simple – some animals are more resistant to a TB infection than others because of their genetic make up.

So, if TB and liver fluke is controlled by an animal’s genetics, why shouldn’t it be possible to breed animals that are more resistant to TB or liver fluke?

Although the TB eradication program has been operating in Ireland for 70 years, it is still prominent in the country. It is something that is costing each and every farmer money; therefore, it is time that a different approach is taken on the issue.


In the same way genetics controls an animal’s milk yield and fertility, it can also control animal health.

Research conducted by Teagasc and Irish Cattle Breeding Federation (ICBF) has identified that certain family lines of animals tend to have a higher prevalence of TB reactors than others. This is the same case for the prevalence of liver fluke infections.

Source: ICBF

You can now select bulls based on their breeding values for resistance to TB and liver fluke.

For example, if a bull has a breeding value of 2% for TB resistance – on average – 2% of his progeny are expected to be TB reactors during their lifetime.

According to ICBF, the number of TB reactors in herds undergoing a TB breakdown is – on average – 26% higher in cows with lowest breeding values for TB resistance when compared to cattle with the best breeding values for TB resistance.

This is the same for liver fluke. The amount of cows diagnosed with a liver fluke infection are – on average – 17% higher in herds with the worst breeding values for liver fluke resistance.

Breeding for TB and liver fluke resistance will aid in the eradication of TB from Ireland and the prevalence of liver fluke in many dairy and beef herds.

This is something to consider when selecting breeding bulls for your herd this breeding season.