Department vet advises against contract rearing over TB risk

The new superintending veterinary inspector for Tipperary has advised farmers against sending heifers to other farms to be contract-reared to mitigate the risk of spreading TB.

Martin Ryan gave this advice while speaking to farmers at the north Tipperary Irish Farmers’ Association (IFA) AGM on Monday night.

He discussed a study, Exogenous reinfection in tuberculosis, which found that 12.5% of TB reinfections on farms came from badgers and 9.7% came from introduced cattle.

“When we think about introduced cattle, we think about bought-in cattle mentally, but nowadays with dairy expansion there’s contract-rearing. Contract-rearing is essentially introducing cattle, that’s something to be aware of.

“If you send your cattle down to an area, you’re adding another area of risk to your herd.

“If I was contract-rearing, I would be going to one person, my cattle only, in an area where I know there’s no TB. That’s what I would do as a farmer to cut my risks down.”

Bulls and TB

According to the Irish Cattle Breeding Federation (ICBF), farmers should select cows and bulls for breeding that have the highest overall index, as well as the lowest breeding value for TB resistance.

To improve resistance, farmers are advised to use bulls with a predicted transmitting ability (PTA) of less than 8%.

High EBI does not guarantee favourable genetic resistance to TB.

“Breeding for TB resistant cattle is coming in and I don’t know how many farmers base their breeding on looking for TB resistant cattle, but it does work,” added Ryan.

Responding to this, Munster IFA regional chair Conor O’Leary questioned why AI companies can sell semen from bulls with low resistance.

“I cannot understand how we let AI companies sell bulls that have a propensity to pass on TB.

“Where [Ryan] said about the ICBF, if we dropped out the bottom third of bulls every year, that would really strengthen our herd.

“[The AI companies] know before they buy calves, the score that [a] bull calf has on resistance and it just seems criminal that we’re continuing to let them buy them,” he said.