Managing Salmonella disease is all about reducing risk. No dairy will ever be exempt from disease exposure, because Salmonella is sneaky and can enter a dairy herd through a number of ways.
Recent cattle purchases or heifers that have returned from a grower can carry disease. The boots or clothing of visitors or workers from a neighboring farm also presents a risk.
Even rodents and birds nesting throughout the barn or hovering around feed bring the possibility of the spread of Salmonella bacteria to an operation.
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A 2007 USDA study of dairies across the country found 39.7 percent of all dairies were infected with Salmonella, nearly double the percentage of herds infected in a similar study 10 years earlier. In addition, the percentage of cows infected with Salmonella has more than doubled to 13.7 percent since 1996.
A 2011 survey conducted at our annual Dairy Wellness Summit found 60 percent of producers in attendance had experienced a Salmonella outbreak on their dairies in the past five years.
More than half of the veterinarians and producers surveyed said they were very concerned about Salmonella disease.
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Producers concerned about the disease can take steps to help reduce the risk of infection to their herd. An important place to start is to work with a veterinarian that can help determine the disease status and identify exposure opportunities on the dairy.
What are the risk factors of Salmonella?
There are several risk factors for Salmonella disease, and many of these are often overlooked on dairy operations. Producers should ask themselves:
• Has the dairy experienced a clinical Salmonella outbreak before?
• Are cattle moved on and off the dairy routinely?
• Are feed ingredients brought onto the dairy from an outside source?
• Are there other animals present on the dairy (i.e., dogs, cats, rodents, birds or waterfowl)?
• Is the dairy expanding or planning to expand in the near future?
• Is the same equipment used for feeding and manure management?
• Is any equipment shared with neighboring farms?
• Do visitors or service providers frequent the dairy (i.e., A.I. technicians, salespeople, veterinarians or cattle haulers) without biosecurity measures?
Answering yes to any of these questions means the dairy can be at risk for Salmonella infection. What’s even trickier about the disease is that it can migrate undetected throughout the herd.
An otherwise healthy-appearing animal can be a carrier for the disease, and although they may never show clinical signs of disease, bacteria remain in her system and can be shed through manure, infecting other herdmates.
What are the steps to take to reduce risk?
The keys to preventing Salmonella disease from sneaking up on the herd are to reduce the exposure of the herd to Salmonella bacteria through a good disease management program as well as to prepare their immune system through vaccination and nutrition to combat the disease if it does strike.
Maternity/hospital pen management: Fresh cows and newborn calves can be highly susceptible to Salmonella due to their compromised immune systems.
Sanitation is key in calving facilities to avoid infecting newborns. If possible, maternity pens should only be used for calving and hospital pens should only be used for sick cows to help minimize disease exposure.
Producers should evaluate maternity pen and hospital pen management procedures to ensure pens are properly sanitized and rebedded between inhabitants to help minimize the spread of Salmonella.
Producers also should ensure employees assisting in the maternity or hospital pen areas receive proper training on animal care and sanitization.
Colostrum management: Contaminated colostrum can be a significant source of Salmonella infection.
Reduce any possible spread of Salmonella by feeding colostrum harvested from healthy cows and pasteurizing the colostrum.
Keep in mind contamination can occur after pasteurization if the colostrum or milk is not stored and handled properly, so be sure to regularly test pasteurization temperatures and time.
Thoroughly sanitize all calf equipment, including bottles, nipples, esophageal feeders, balling guns and syringes after each use to help prevent contamination.
Be sure the sanitizer used is labeled for Salmonella or gram-negative bacteria and follow all label instructions, including dilution and required contact time.
Crossover traffic of people and cattle between calf pens, fresh pens and hospital pens can greatly assist in the spread of disease.
When working with newborn calves, employees should wear clean coveralls and boots and practice proper sanitization of hands and boots when entering and leaving different areas.
Feed equipment: It is best not to use the same equipment for feeding, manure removal or cattle transport to help prevent cross-contamination.
Borrowing or lending equipment to and from other farms also poses a great risk for introducing Salmonella to the herd. If producers must use equipment interchangeably between tasks and between farms, enforce proper cleaning and sanitization protocols, especially before handling feed.
Feed ration consistency: Adequate nutrition is the staple for supporting overall health, and consistency is key.
Be sure to use a consistent feed supplier to reduce frequent changes in diet and feed ingredients, which can be a source of stress to the herd, making them more susceptible to disease.
A functioning rumen is essential for immunity and combating Salmonella. Rumen functionality and volatile fatty acids production is enabled by feeding diets higher in forage.
Whole-herd vaccination: In addition to adequate nutrition, vaccinating the herd for Salmonella is also pivotal in effectively controlling infection and fecal shedding of the bacteria.
Practicing whole-herd vaccination allows producers to create whole-herd immunity. Whole-herd immunity can be achieved by vaccinating cows at dryoff by using a demonstrated vaccine.
How can the risk of Salmonella disease be controlled?
The best way to know if Salmonella is present is to work with a veterinarian to culture both cattle and key exposure areas.
Common Salmonella hotbeds on a dairy include fresh cow areas, such as close-up pens and calving pens and calf housing areas. Purchased animals also should be cultured and quarantined from the rest of the herd until confirmed disease-free.
In addition to working with their veterinarian to determine Salmonella risk, producers and veterinarians should discuss, and then implement, appropriate on-farm control strategies. A Salmonella control program should include:
• Establishing colostrum management SOPs
• Evaluating management practices that impact Salmonella risk
• Incorporating biosecurity SOPs of employees, visitors and equipment
• Discussing the role of Salmonella vaccination.
Remember: No herd is completely protected from Salmonella disease, but recognizing the risks and taking proactive control measures with guidance from a veterinarian will help lessen the likelihood of a disastrous outbreak. Visit www.salmonellarisk.com to learn more about the risks of Salmonella. PD