PRINCETON, N.J. — Salmonella causes a significant amount of foodborne illnesses every year.
“Typically we have 1 million to 1.5 million people infected a year from salmonella, 23,000 are hospitalized and 500 of them die,” said Jack McReynolds, R&D technical director at Arm & Hammer Animal and Food Production.
“Most people infected with salmonella get the bacteria from contaminated food or water,” McReynolds said during a webinar. “About 2,500 types of salmonella exist today and 30 of those have human health significance.”
Salmonella can be a problem for cattle at any age.
“The disease can be passed from mom to calf and all the way through adulthood,” McReynolds said. “Animals can be carriers and asymptomatic, so dairy herds can become endemic with the problem causing substantial losses in production.”
A study tested 5,000 isolates from Wisconsin dairies.
“Salmonella dublin was the post prevalent serotype identified,” McReynolds said. “Twenty-three percent, or 1,153 samples, were salmonella dublin.”
Salmonella dublin is a host adapted strain, McReynolds said.
“Cattle can become chronically ill, subclinical carriers and have the potential to shed extremely large numbers of the organism,” he said. “We all have a responsibility to try our best to reduce point sources of contamination so we grow healthy cattle entering the food supply chain.”
McReynolds stressed the importance of disease monitoring and surveillance.
“That needs to be coupled with better communication between the animal industry, veterinarians and government regulatory authorities, as well as with the public to help establish control measures for emerging infectious diseases,” McReynolds said.
“Dublin is a little different than the rest because it sheds more in the springtime than in the fall,” he said. “We think this is associated with pregnancy and calving stress in the spring that weakens the cow’s immune system and increases the likelihood of infections.”
On dairy farms, McReynolds said, manifestations are common between the seven- to 10-week period during the transition period for calves from milk to grain rations.
“This time period is a critical opportunity to help prevent or reduce the incidence rate of salmonella in dairy herds,” he said.
Steps to reduce salmonella include sanitizing and cleaning calf equipment including bottles, nipples and syringes after every use.
“Read the label of the product you are using to make sure it is a disinfectant or sanitizer,” McReynolds said.
“Salmonella dublin is an opportunistic pathogen that really wants to impact animals with compromised immune systems,” he said. “Adequate intake of clean, quality colostrum is one of the most important steps.”
McReynolds recommends feeding calves four quarts of high quality colostrum within two hours after birth and an additional two quarts of colostrum six to eight hours later.
“Using hygienic practices with harvesting colostrum is really important,” he said. “Pasteurize the colostrum for 60 minutes at 140 degrees, followed by cooling and feeding.”
Calves with salmonella scours won’t want to drink milk, McReynolds said.
“They will have a high fever, watery diarrhea and dehydration sets in quickly,” he said. “We need to get electrolytes in them, as quickly as we can.”
The calving facilities need to be clean and well bedded.
“One cow per stall helps to reduce and eliminate fecal contamination,” McReynolds said. “Move calves to a clean, individual hutch and any animal that is sick should be isolated.”
Healthy calves produce good cows, McReynolds said.
“Healthy calves gained about a half pound more body weight, and they also produced 1,250 gallons more milk,” he said. “That shows an return on investment to bring the calves into a healthy environment and give them the best start that we can.”
McReynolds encourages dairymen to test for salmonella dublin when new animals are brought into a herd.
“Check cows to make sure they have been vaccinated, and if they aren’t, bring them into a vaccination program so you know exactly what’s on your farm,” he said.
Reducing heat stress is really important for dairy cows.
“Make sure we’re providing shade for cattle and cooling fans because heat is commonly tied with salmonella in cattle,” McReynolds said.
“The main barrier function against salmonella in cattle is maintaining a good gut microbiome by having the right feed,” he said. “Salmonella has a hard time colonizing when there is a good microbiome.”
Oral exposure to salmonella can lead to infection which means waterers need to be cleaned.
“Cows can consume from 5 to 15 gallons of water at a time,” McReynolds said. “So, every time she drinks she can build the pathogen load.”
In addition to heat, drought also has a major impact on salmonella.
“In 2011, 85% of Texas was in extreme drought,” McReynolds said. “The prevalence rate of salmonella was about 19% higher in those extreme drought conditions.”
“Our mission at Arm & Hammer is to unlock opportunities to feed the world by improving animal and food production systems,” he said. “Our goal is to motivate and research animal and food production systems to bring great technologies that help in all animal welfare and disease conditions.”