A college farm which bought in cattle to replace TB losses is counting the cost in lost production and record empty rates after the replacements infected existing stock with BVD and IBR.

Empty rates in the spring herd at Gelli Aur, Carmarthenshire, have soared from 7% to 20% and farm manager John Owen links this directly to bulling and in-calf heifers bought in after 300 cattle were destroyed after a major TB breakdown.

The farm was previously clear of BVD and IBR.

Mr Owen says the economic impact of these new diseases has hit the business hard. Fertility performance has dropped off markedly and this is having a considerable impact because we run a low-cost, low-output system,'' he says.

The empty rate in the autumn calving herd is running at 25%, although this has been higher at 30%.

All breeding stock on the farm have now been vaccinated and a herd health plan is in place.

The risk of importing diseases with replacement stock means the long-term losses from TB can be far greater than the initial outbreak, according to Mr Owen.

As farmers we are quite resilient and get over the initial shock of TB, helped somewhat by compensation for culled stock. But the long-term losses, as we have personally experienced, can be far greater,'' he says.

One hundred and fifty replacements, including crossbreds and 47 Norwegian Friesians, were bought in from Scotland and Anglesey, areas both free of TB.

It worked out fine in terms of TB biosecurity but, when you buy in animals, you have the added problem of buying in other diseases,'' says Mr Owen.

Losses at calving among the bought-in stock have been far greater than within the home-breds. We calved a similar number of each and we lost four of the replacements but none of the existing stock,'' says Mr Owen.

Isolating replacements for 60 days and introducing them to the herd just prior to calving may not have helped, he reckons, because of the added stress this placed on the animals.

Although TB continues to be an issue on the farm, there was some relief when the last 60-day test recorded a single reactor and one inconclusive.

But Mr Owen believes this is the worst stage of all. Two years down the line we are suffering because we are still under restriction and we have poor performance in the herd.''

The farm has now increased cow numbers in the spring-calving herd to the projected 250 and, by next autumn, there will be a similar number of autumn calvers. The Norwegian Friesians were introduced to boost fertility in the herd.

But despite setbacks on the disease front, the herd continues to move forward, with cows being milked through a new, £220,000 parlour and changes also being made to feeding policy to maximise productivity.