Managing Salmonella on farm

As I write this it is a couple of days after 35mm of rain, most people have their crops in the ground and the maize is just getting going. After what has been a relatively kind spring for most in our area it is easy to forget how quickly things can change. Southland is an area that is used to plenty of rain. However, this spring has been something out of the ordinary with significant flooding leading to massive stress and animal welfare that have been associated with this weather event. 

A significant issue that has raised its head in Southland during this period is a marked increase in the number of Salmonella cases. Historically Southland has had very few cases of salmonellosis compared to regions like the Waikato. However, this spring Southland has been severely impacted. 

As you will remember, Salmonella causes sudden milk drop, scour which is often bloody, abortion, fever, and death, which can occur before any other symptoms are seen. Outbreaks can be sudden and affect large percentages of the herd. Certain risk factors have been associated with outbreaks such as poor hygiene, changes to rumen pH such as feeding large amounts of carbohydrate or granulated magnesium and periods of high stress.

As can be seen from the list of risk factors this is exactly what happened on some farms in Southland. Pastures were flooded causing effluent contamination of pastures. Due to the flooding, many farmers were left with no choice but to feed large amounts of supplement and of course, the cows are under huge pressure in these conditions. Unfortunately, this has led to many Salmonella outbreaks. Associated animal welfare and financial impacts in affected herds have compounded the stress for these farmers. I can only imagine how difficult it must be for these individuals to deal with the flooding as well as trying to deal with a Salmonella outbreak. 

Also, we must remember that Salmonella can affect humans as well, and when cases of Salmonella increase in cattle, human cases increase too. Imagine trying to deal with a crisis on farm when you or a family member are in hospital with Salmonella.

Although cases in Waikato have been down over the last couple of years, this does not mean that it has gone away. Have a chat with your local FVS vet and have a plan for managing Salmonella risk on farm. Don’t wait until the wheels fall off after a wet spring or flooding.

Dr Brent Neal - BVSc MANZCVS Veterinary Pharmacology, Pukekohe