Monday 26 September 2016

Dairy farmers dice with disease

Published 08/07/2015 | 02:30

Herd health: Approximately €20 per cow will cover vaccination costs for major diseases
Herd health: Approximately €20 per cow will cover vaccination costs for major diseases

A BVD outbreak in Moorepark resulted in losses totalling €30,000, farmers were told at the open day in the research centre last week.

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"The breakdown stemmed from an incorrect vaccination procedure," explained Riona Sayers, disease expert at the centre.

"We were trying to get the booster vaccine administered in time before the breeding season started, which meant that the required three week wait between the first and second vaccination was reduced to just one week.

"As a result we had naïve pregnant heifers that had been reared separately mixing with the main herd for the first time. We ended up losing 18 calves, along with losses in milk yield, veterinary treatments, and a major fall in conception rates due to early embryonic deaths that amounted to €30,000 for the 80 cow herd," she said.

The incident highlighted how fragile biosecurity systems are on many farms, with farmers often unaware of just how costly disease breakdowns can be.

"Animal Health Ireland estimate that endemic BVD costs €63/cow, while Leptospirosis and Neospora both cost €12-14 each. IBR is another significant cost on a herd, resulting in 250kg less of milk per cow in affected herds, but Salmonella is the worst, with at least 300kg of milk losses. If there are Salmonella carriers in a herd, you're looking at losses of €112/cow on average," Dr Sayers told farmers at the event.

Despite the significant financial risks, it is estimated that just 50pc of farmers vaccinate their animals against the disease, with up to 80pc vaccinating for Leptospirosis. The disease expert also warned farmers that a vaccination for Salmonella administered in October would not confer protection to calves born after January.

"We used to vaccinate later in the autumn here in Moorepark, but we've moved it forward to August to avoid abortions. That means that we need to vaccinate again in the spring 3-4 weeks before calving to ensure that the calves are covered too," she said.

With both Salmonella and Leptospirosis posing a threat to people that come in contact with the infected animals, Dr Sayers believes that there is justification for a national initiatives for both diseases.

"We really should have a national vaccination programme for both of these diseases. But farmers should also be looking at the free ways that they can increase the biosecurity on their farms. Quarantining new animals for up to 30 days is a seriously under-utilised way to save your entire herd from the risk of something being introduced from a bought-in animal," she said.

Dr Sayers added that footbathing animals as soon as they arrive on the farm was another sensible measure that more farmers should seriously consider.

She also cautioned expanding farmers to consider the increased risks of contract rearing stock and taking on additional out-farms.

"Contract rearing automatically increases a farm's fragmentation, which in turn raises the biosecurity risk. This is just one of the infrastructure considerations that many farmers seem to forget about when they are expanding. The other one is the facilities for calves - that's something you just can't compromise on," she said.

She believes that a spend of approximately €20/cow would cover the cost of vaccinating for the major diseases such as Leptospirosis, BVD, Salmonella and IBR.

"There are lots of different types of vaccines out there for IBR, but we are not seeing any difference in the effectiveness of any if there is no outbreak in the herd. On the other hand, if there is IBR in the herd, a live vaccine is the only one that will do the job."

However, Dr Sayers cautioned farmers not to forget about the stock bull when they are rolling out vaccination programmes for their herds.

"The number of farmers that overlook the bull is mind boggling and, at 70pc, Ireland has one of the highest rates of stock-bull usage in the world.

Johnes threat

Ireland is at risk of being shut out of international dairy markets if it does not get on top of the problem in the coming decade, according to one of the country's top bovine disease experts.

"If we're still Johnes positive in 10 years and another country is negative, people are going to stop buying our milk," Dr John Mee told farmers visiting the Moorepark open day in Cork last week.

He said that despite completing two surveys, Teagasc were still unclear as to the exact extent of the disease within the Irish herd.

"Tests for Johnes aren't as good as BVD - that's just life. But from what we can see, up to 30pc of herds have at least one cow that tests positive for exposure to the disease. But only 2-3pc of animals surveyed actually showed any exposure to the disease.

"It is likely that the majority of infected animals get culled out of the herd due to their higher levels of lameness, infertility and mastitis. There's very few clinical cases, and that's the way we need to keep it," he said.

BVD Vaccination

One of the most common questions on the day was whether farmers could afford to stop vaccinating for BVD after three years of testing and vaccinating for the disease.

"It all depends on your appetite for risk," answered researcher Dr Mee.

"If you have confidence in your fencing, boundaries, animal movements and vaccination regime, it's certainly an option. But this varies hugely from farm to farm."

He also highlighted how easily the disease can be transferred from animal to animal.

"BVD can be transmitted by cars, flys, scanners that may be carrying a bit of blood on their glove from the previous animal.

"So it is a difficult disease to contain without vaccination," he said.

Dr Sayers highlighted that the incidence of BVD has halved from 0.7pc in 2012 to 0.3pc of animals tested now. This means that there are just 2,000 persistently infected (PI) animals left in 7pc of herds, but this "tail-end" of the disease was the hardest part of the eradication programme to manage.

"It would be great if we could just go in there and take the lot of them out in one go, because then we'd be done with it," said Dr Sayers. "And if you do have a PI at home that you've decided to fatten up for the freezer, would you ever just get rid of it!"

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