Salmonella infection can have a devastating effect on Irish herds.
“It was a horrendous experience. I just dreaded going out to the yard every morning,” said Cork dairy farmer Kevin Gowen as he related the story of the outbreak of Salmonella infection in his herd in 2010/11. “At the time, I was milking 100 cows. I was vaccinating for everything else, but not for Salmonella. We operated a closed herd, so I felt there was no risk. “And then it hit. Sixteen cows aborted in the space of a few weeks. I never want to go through that again,” said Kevin, who farms at Cappagh, Ballyhooley.
His veterinary practitioner Paul Redmond from Duntahane Veterinary Clinic in Fermoy was involved from the day the first abortion took place. Salmonellosis was rapidly diagnosed as the cause. The cows that aborted were segregated and all cows and in-calf heifers were vaccinated with Bovivac S. “We had to run two herds for a considerable period, which really increased the labour and management load. We eventually got rid of all cows that aborted and bought in cows and heifers to replace them,” said Kevin.
He is now milking 115 cows and producing his own replacements, some of which are reared on contract. Vaccination with Bovivac S is a non-negotiable part of his animal health programme. Replacement heifer calves are given a full primary course of the vaccine in September. All cows and replacement heifers are then given their booster shot annually during the month of September.
Paul Redmond stressed the importance of vaccinating with Bovivac S at least two weeks prior to the high risk period to reduce the chances of subsequent Salmonellosis developing. “The high risk period is from the fifth to the eighth month of pregnancy. In problem herds it is essential to time your booster shot a few weeks prior when disease normally arises on your farm,” said Paul.
Paul is one of six vets in the Duntahane Veterinary Clinic which provides cattle, sheep, equine and pet health services. He is also chair of Prime Health Vets, a group of almost 20 veterinary practices across the country which pools knowledge and expertise with the aim of enhancing the quality of service to its farmer clients. “As well as causing abortions, Salmonella infections also cause severe disease in calves. Clinical signs include diarrhoea, joint infections, septicaemia pneumonia and fever. Calves regularly die within a few days of picking up the infection. “A number of years ago, I came across cases of per-acute salmonellosis in calves where the best calves in the bunch just dropped dead as if you shot them with a bullet.
“The two strains that affect cattle, Salmonella dublin and Salmonella typhimurium, are highly infectious. Bacteria are shed in birth fluids and faeces from infected cattle and are spread through contaminated water, feed, milk, equipment and wildlife. The bacteria can be carried by apparently healthy carrier animals. Stress factors, such as parasite infections, particularly fluke, and poor nutrition, can trigger an outbreak,” said Paul.
“Heifers infected between the age of one year and first calving are at the highest risk of becoming carrier animals. This is why these animals should be vaccinated before the risk period,” he added. He sees a severe outbreak of the disease in a client’s herd every couple of years. It is always in a herd that is not vaccinated or where vaccination has been discontinued. “We still have a significant number of clients who are not vaccinating. Considering the devastation that an outbreak of Salmonella can cause, this is false economics.”
His advice to all his clients is to give a primary shot of Bovivac S to all replacement heifer calves in August/September followed by a booster shot three weeks later. Replacement heifers and cows should then get their annual booster shot during the month of September. Bovivac S is the only vaccine that protects against the two strains of Salmonella, most relevant to cattle in Ireland. “Vaccination, combined with good hygiene and care in buying in, is the only way to prevent this serious disease,” he stressed.
Cara Sheridan, technical adviser with MSD Animal Health, highlighted the results of a recent study by Teagasc at Moorepark on the economic cost of Salmonella exposure in non-vaccinated herds, even in the absence of obvious signs of disease.
“The survey showed that exposure to Salmonella reduced profit by €77/cow at a milk price of 24c/l and over €110/cow at a price of 34c/ litre. It further showed that herds vaccinated for Salmonella recorded superior profits to unvaccinated positive herds (€84/cow). Herds negative for exposure generated the best profits of all. However, the cost of maintaining a Salmonellafree herd is currently unknown,” said Cara.
According to Cara, “Salmonella dublin and Salmonella typhimurium are the two most relevant cattle strains”. In fact, a recent study, conducted in Cork Regional Veterinary Laboratory, revealed that Salmonella dublin accounted for 85% of Salmonella isolates and Salmonella typhimurium accounted for 11% of isolates.
She urged farmers to seek the advice of their veterinary practitioner before implementing a Salmonella control programme.