VACCINATION, REGULAR footbathing and maintaining a closed herd have been necessary since one 200-cow herd bought in a few surprises with its purchase of 35 replacement cows in 1999.

Digital dermatitis, Johne’s and Infectious Bovine Rhinotracheitis caused yields to drop and fertility to suffer. Herd manager Andy Ward has been working with the farm’s vet ever since to repair the damage, restoring milk yields to 8000 litres and conception rates to 56%.

“We have always vaccinated against leptospirosis but we now vaccinate for Johne’s and IBR, too,” says Mr Ward who manages the herd in Westerham, Kent.

“We have started rearing our own replacements and manage colostrum to prevent spreading Johne’s.”

Problems started the first winter after cows were bought to replace higher than expected culls for neospora abortion. “Cows were selected on paper then picked according to looks, whether they fitted our August to December calving pattern and our price range,” he says.

Some cows had milk records complete with cell count data, others had none. But they were all bovine TB-tested in the previous two years, he adds.

Mr Ward first spotted digital dermatitis during winter housing, something he hadn’t seen in the herd before. “It was more noticeable in milking heifers – even now we find younger cows seem more susceptible – but it didn’t take long to spread.”

Regular footbathing now controls it to a certain extent. However, it is worse in winter and can reduce fertility as cows don’t want to stand for bulling. Plus they would rather lie down than stand at the feed fence, resulting in below par yields.

Next came a bad outbreak of IBR in winter 2000. “We had cows coughing and running high temperatures, bulling heifers with runny noses and yearling heifers with bad eyes. Because we had 25 cows on antibiotics we had to dump a lot of milk and infertility followed.”

Conception rates fell to just 32%. The calving pattern, which wasn’t very tight before, spread from August to May after the outbreak and some cows were dried off empty.

Mr Ward didn’t want to cull too many and have to buy in more. “Extending the calving pattern was better than buying in more diseased animals,” he says. Calving has since been tightened to a September to January block. This fits in better with labour, housing and grazing resources.

Finally, Johne’s hit. There is still debate about the source, although he believes it can be traced to bought-in cows. “We had very thin, scouring cows and had to cull seven. Two years later we had another five, and one confirmed case under 30 months. One cow giving 45 litres dropped to four litres, then died three days later.”

As a result, heifers are only fed their dam’s colostrum before moving onto milk replacer and are vaccinated at four weeks of age.

Learning a valuable lesson from buying in stock, Mr Ward says that when a sweeper bull was needed, he insisted on sourcing from a local farm where the animal was isolated for three weeks.

“We tested him for IBR, BVD, leptospirosis and Campylobacter, then vaccinated for everything before bringing him here. He was quarantined here too.”

It has, however, taken five years to reduce the rollercoaster effect disease has had on milk output from the herd. When dealing with neospora, the annual rolling average dropped to just 6600 litres. It was climbing steadily, on line for 8000 litres, when IBR hit and sent it back down, says Mr Ward.

Extra colostrum management may be a hassle. But vaccinating heifers only takes two hours a year when organised, using good handling facilities and combined with another job such as worming. Both are a small effort compared with the cost of disease, says Mr Ward. But now the herd has had no IBR or Johne’s for over a year.

“I would advise those buying in stock to have them tested for diseases. This is easier in in-calf heifers or dry cows because they can be isolated.”

BUYING-IN COWS

Select heifers or dry cows

Test for diseases

Isolate before mixing

shirley.macmillan@rbi.co.uk