Study reveals impact of cleaning methods on chicken gut health

Canadian broiler producers are required to deep clean their barns with chemical disinfectants at least once per year, but how they clean between flocks is a little more fluid. Some producers opt for a full disinfectant with every cleanout, while others may choose to wash with just water between flocks.

It’s an important biosecurity decision that has the potential to impact food safety and flock health. Now, for the first time, research looks at how both options impact chicken gut health. 

Dr. Yi Fan, Department of Agriculture, Food and Nutritional Science at the University of Alberta, has completed a study evaluating the effects of barn cleaning methods on various factors affecting broiler health. His results suggest that, for barns that have had no challenges with disease outbreaks, a water wash may be healthier.

“Our results suggest that water wash may result in enhanced activity of the gut microbiota and they seemed to be more naturally resistant to pathogenic bacteria,” says Fan. 

Two ways to clean
The study involved 28 production flocks raised in barns without any prior history of disease outbreaks. A commercial broiler facility in Alberta provided the chickens and facilities for the project, including seven cement-floored production houses at two locations. Over a 10-month period, the researchers studied 14 flocks raised in barns that employed each cleaning practice.

In all of the flocks studied, barns had been cleaned thoroughly. Chicken manure, used litter and organic matter were completely removed. The full disinfection cleaning practice included foam and high-pressure and low-pressure wash and air drying. The water wash process included low-pressure water rinse and air drying. 

Cleaner may not be better for gut health
The researchers tested litter samples, feeding pan samples, drinker samples, and shoe-cover samples. They also evaluated broiler performance and gut health indicators such as the composition of the cecal microbiota, Campylobacter and Salmonella occurrence, and short-chain fatty acid composition. 

“Our results revealed that barn cleaning methods had little impact on the 30-day body weight and mortality rate of broiler chickens, which would also suggest an absence of subclinical infection,” says Fan. “From the beginning to the end, we did not recover any salmonella from the environment or the chicken gut.”

Most tellingly for Fan, was the subtle but significant effect on the broiler cecal microbiota that resulted from the two cleaning practices. The full disinfectant treatment showed increased abundance of cecal Campylobacter associated with decreased concentrations of short-chain fatty acids (SCFA). 

In general, the gut microbiota-derived short-chain fatty acids increases the gut acidity, which creates an environment that is less favourable for many pathogens. Fan notes these fatty acids also act as fuel for intestinal cells, and play an important role in modulating immune responses.

“This would support the adoption of water wash as a standard practice, because compared to full disinfection, water wash can be beneficial to the broiler chicken by altering the gut micro-environment towards a more homeostatic state with reduced cost and labor of cleaning,” says Fan. 

Flock immunity adapted over time
To understand why this might be the case, Fan suggests it’s important to look at chickens in natural environments. In nature, chicks are hatched by hens, and the parental flock passes their microbiome to the chicks. Fan notes that in modern production systems, eggs are collected and transferred to a clean hatchery, and then chicks are transported to barns. 

“In our modern production system, we artificially cut the beneficial microbiome connection between hens and their chicks,” says Fan. “Using chemical disinfectants removes a high proportion of microbes, but it may also reduce the transmission of beneficial microbes between flocks. This could lead to a potential loss in the microbes that can outcompete pathogens in the environment.” 

There’s value in a good clean
Whether producers opt for once a year or a more regular full disinfection, it’s important to get it right. Michael Ryan is the owner and general manager of Jeni Mobile Wash Ltd, an Ontario-based cleaning service. 

“The goal of a proper wet wash with detergent and disinfectant is to get the disease threshold in the barn as low as possible.” Ryan says. “If the wet wash isn’t done well, all you’re doing is getting the bacteria in the barn wet.”

Ryan says some producers call in his experienced crew once they’ve run into a disease challenge. It takes time to clear up the problem.

“It’s more challenging to control a disease in a barn that hasn’t been washed properly in a while because things build up,” Ryan says. “And when you don’t have the option of using antibiotics, it becomes more important to start with a clean barn, and give those birds the best start possible.”

Decisions are personal
Fan admits it’s a “great responsibility” to advise growers on biosecurity decisions, especially without the tool of antibiotics if an outbreak occurs.

“For producers who feel confident in their flocks, who have not had a previous disease challenge in their barns, this gives them the confidence to continue cleaning between flocks with a water wash, and the research supports they should not lose chicken performance or see increased mortalities,” says Fan. 

All of the barns in this study were from a nonchallenging commercial production setting.  He says further studies examining other barn disinfection practices, and testing for other pathogens are warranted to identify the best practices to minimize pathogen load and maintain animal performance. 

This research was supported by the Alberta Livestock and Meat Agency, the Alberta Chicken Producers, the Results Driven Agriculture Research, and the Canadian Poultry Research Council.