NULLAWARRE dairy farmers Tim and Bronwyn Lenehan survived a costly bovine pestivirus (BVDV) scare.
They say the key to their survival was quick action in identifying and eradicating the virus.
Mr Lenehan admits that the virus could have destroyed the farm.
"If we had seasonal instead of split calving, it would have been disastrous," he said.
As it was, he estimated the outbreak cost $250,000 and the effects were still being felt on the farm today, despite the quick response and his farm's excellent history of milk testing and record keeping.
The Lenehans hosted a Warrnambool Veterinary Clinic FarmChat forum last Friday to tell their story as a warning to other farmers and to encourage them to take samples and test for the virus.
BVDV is very common on dairy farms, but rarely causes obvious production losses.
However, when introduced into a naive herd it can cause greatly reduced conception rates, abortion and deformed calves.
The problem was detected on the Lenehan farm in 2012 during pregnancy testing with Dr Jon Kelly from the Warrnambool Veterinary Clinic.
Dr Kelly said the high empty rate was unusual for the farm which had no previous exposure to BVDV.
"Nothing had changed from previous joinings but the conception rate was only 28 per cent, so we took a bulk milk sample for testing," Dr Kelly said.
The bulk milk tank antibody testing was carried out by Dr Enoch Bergman at Swans Veterinary Services in Western Australia to identify if there were Persistently Infected (PI) cows in the herd.
"We suspected the problem was with the first calving heifers but we had to prove it. So they were segregated, milked last in the herd and a bulk milk test taken before and after their introduction," Dr Kelly said.
"It was an easy way to rule out the other 400 cows in the herd, which saves ear notching every animal."
Dr Kelly said there was only a small window of time to identify and eradicate the virus before the next joining period and the farm was lucky it took prompt action.
"Every time you do pregnancy tests you should get milk samples done and test them to find out if there are antibodies," he said.
"The good news is that like Tim and Bronwyn, you can do something about it and get back on track."
"We were able to identify and eradicate it and make sure it won't happen again."
As a result of the virus, the farm suffered low conception rates, spread out calving pattern, reduced milk supply, less heifer calves born and more culled, and has since found it harder to get cows in calf.
"We had about 120 cows not in calf," Mr Lenehan said. "The conception rate was pretty disastrous. We usually have enough for herd replacement and to sell for export but we didn't in 2012 which was a tough year all round.
"Luckily we have split calving so not all the herd was exposed, but the effects take time and we're still feeling it," Mr Lenehan said.
"We were lucky we were able to identify where it got into our herd. It was critical that we took samples that helped us to get on top of it so quickly."
Mr Lenehan and Dr Kelly believe the pestivirus was most likely introduced when leased bulls were brought onto the property.
The farm now operates as a closed herd and any bulls brought in must be ear-notched.
Mr Lenehan said bulk milk tank antibody testing and blood testing yearling heifers "is the most important thing you can do on your farm".