5 keys for controlling Salmonella on breeder farms

Continuously reducing the amount of Salmonella on the farm depends upon biosecurity, clean feed and water and good disease intervention strategies.

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Courtesy Aviagen
Courtesy Aviagen

A broiler breeder farm should strive to be Salmonella free, but that may be impossible. A more realistic goal is to continuously reduce the amount of the pathogen on the farm.

Dr. Eric Jensen, Aviagen North America’s vice president of veterinary services, spoke about controlling the presence of Salmonella on breeder farms as part of the Biomin World Nutrition Forum in Cape Town, South Africa, in October 2018. A Salmonella reduction strategy depends upon five keys: structural biosecurity, operational biosecurity, clean feed and water, salmonella interventions and maintaining a culture of biosecurity.

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Dr. Eric Jensen, Aviagen North America | Courtesy of Biomin

1. Structural biosecurity

Site selection: Isolation is essential in building new farms or expanding existing ones. Both nearby livestock and crops are potential sources of Salmonella, so farms should be located far away from them. Crops harbor rodents and other small animals. When they are harvested, they generate a lot of dust, too. To establish better disease control, breeder farms should be small and the entire flock should be all in all out, meaning they enter the farm at the same time and leave at the same time.

Housing: Wildlife, pests and domestic animals must be excluded from entering poultry houses.

It’s hard to restrict the movement of both rodents and personnel. Investments should be made in exclusion of these disease vectors. In older farms, rodents climb up concrete foundations and enter through the spaces between the foundation and the metal side walls. These houses can be renovated with slick and pointed-down aluminum flashing to keep rodents from climbing in. Newer housing is well sealed in order to prevent entry.

Cement curbing on the farm’s perimeter fencing provides superior protection by not leaving any low spots under the fence for rodents. Electric fencing around this external barrier and around the foundation of the house prevent rodents from finding cracks to sneak into the house.

Moreover, in-house rodent control specialists should inspect the house every two weeks to inspect the status of rodent traps and the electrical fencing. They should also check potential rodent dens like the surrounding vegetation.

Aside from rodents, farms can experience problems with frogs, lizards and snakes, as well as insects and dust. All of them are vectors of Salmonella, which can ultimately infect the birds. One idea is to place a flying insect barrier along the walls of each side of the house. This wall should consist of a 3- to 4-meter (9.8 to 13.1 feet) span that stretches from the roof to the foundation. Jensen said this works like a dust filter, too.

2. Operational biosecurity

Personnel: Wash-in, wash-out is the best policy for personnel working at breeding operations, as well as using separate clothing for the biosecure areas. The Danish entry, consisting of a station to change boots, clothing and disinfect hands, is also used, but it’s not as effective as wash-in, wash-out.

Upon entering the house, it’s necessary to follow additional sanitation procedures like boot and hand washing.

“That's the most likely way a person’s going to carry Salmonella in from outside into the bird areas,” Jensen said.

The foot traffic from inside to outside the house to weigh feed, remove daily mortality or maintain the perimeter represents a constant risk for contamination. Adding a feed hall – extending from the side of the house and using a window that a person can use to access exterior areas – and keeping scales inside the house can minimize foot traffic.

For older farms, consider adding covered walkways between houses so people don’t have to go outside again after entering a biosecure area.

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Disinfection of feet and hands is necessary when entering the breeder house. | Benjamín Ruiz

Cleaning and disinfection: The houses should be treated like a processing plant because they are food-producing facilities. This takes a dedicated, trained team responsible for things like cleanliness of the farm. Management should be committed to giving a sufficient down period between flocks, at least four to six weeks, to clean the breeder farm, too.

“We have found it very useful, in addition to our routine disinfection, to come back with formaldehyde disinfection, either liquid or gas,” Jensen said. “Formaldehyde is the best disinfectant ever.”

Another recommendation is to spread liquid lime around the perimeter of the house.

Salmonella monitoring: A good idea is to routinely monitor the exterior of the houses to look for Salmonella. If it’s detected, an additional application of lime can be done to help prevent it from entering the house.

Bedding material: Pine wood shavings dried at a high temperature are basically sterilized. A humidity level between 10 to 12 percent is very inhospitable to Salmonella. However, these shavings are easily contaminated. Therefore, it’s essential to maintain biosecure storage and use dedicated delivery vehicles.

3. Feed and water

Heat treatment: Jensen said there’s nothing that will spread Salmonella though an operation as quickly as contaminated feed. The best way to eliminate Salmonella in the feed is using a heat treatment of 85 degrees Celsius (185 F) for six minutes. This way, a five-log reduction of coliforms per gram of feed is achieved.

Heat treatment, however, is very expensive; it slows down feed production, and it negatively impacts the nutrient levels and gravely affects enzymatic activity.

There are more options available to lower the probability of feed carrying Salmonella. To achieve a more typical three-log reduction in coliforms, a much shorter heating period of four minutes at 80 C (176 F) can be used. With the addition of organic acids, this period can be shortened even more.

Formaldehyde: The compound is very effective at a maximum rate of 3 kilograms (6.6 pounds) per ton of feed. Formaldehyde, combined with organic acids (at 3.6 kg/ton or 7.9 lbs/ton), also eliminates mold in feed and has a residual effect preventing recontamination. It also decontaminates feed lines and feed bins.

Recontamination: To prevent recontamination of treated feed, it’s important to separate dirty areas from clean areas in the feed mill. An enclosed door storage bin and load out is needed to prevent recontamination of feed. One of the greatest risks is the cooling room, where large volumes of air to cool the feed enter and much moisture is released. Moisture and dust from the feed are conducive for growing Salmonella.

4. Interventions

Vaccination: The use of inactivated bacterins doesn’t prevent infection, but it does eliminate, or decrease the amount of, vertical transition from the parent to the progeny when used in conjunction with egg shell sanitation. Autogenous vaccines incorporate the specific serotypes from the pathogenic strains that are impacting operations and they are the ones that work best.

Probiotics, prebiotics and organic acids: Good intestinal health in the chick is most likely to repeal challenges. There are many probiotics on the market that should be evaluated for their effectiveness in each particular system. The combinations with prebiotics are very effective, due to their symbiotic effects, as well as organic acids.

The application of these products in feed is best, however, they cannot withstand heat treatment. It’s recommended to administer them in the water lines twice weekly. But this should be coordinated with other products that are offered such as disinfectants, antimicrobials, vitamins or vaccines.

5. Culture

This is the hardest thing for a company to establish. In a biosecure culture, everyone who interacts with the birds or the eggs should understand that biosecurity should be their first priority whenever they do anything. This should be obligatory and part of a continuous process. Culture is a team effort that requires education and communication. It should be constantly revised and adjusted, too.

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