Microbial Screening of Housing and Equipment Before the Arrival of Day-Old Chickens

Cleaning and disinfection are essential parts of farm management biosecurity. The present study aimed to evaluate the presence of opportunistic bacteria on environmental surfaces and equipment in broiler houses on Day 0, just prior to the arrival of day-old chickens. Samples were collected from nine broiler houses, located on different farms in two provinces in Southern Vietnam. Five swab samples were randomly collected from each house, focusing on ceiling and wall surfaces, fan blades, feeders, and drinkers’ heaters. Each environmental sample was analyzed for coliform and Staphylococcus aureus (S. aureus) counts and for the presence of Clostridium perfringens (C. perfringens). Before placing chickens in the houses, samples were collected from 10-day-old chickens on each farm. Feather swabs were collected from the body surface for Escherichia coli (E. coli), Salmonella species, and S. aureus, while yolk samples were screened for E. coli and Salmonella species. High bacterial loads were detected in all environmental samples. Specifically, coliform and S. aureus counts reached 6 log10 CFU/cm2 from ceilings and walls. Additionally, equipment surfaces demonstrated substantial bacterial contamination, with counts of 6-11 log10 CFU per feeder or drinker, 9-11 log10 CFU per fan blade, and 6-10 log10 CFU per heater. Clostridium perfringens was found on environmental surfaces and equipment in most broiler chicken houses, except for houses 1, 3, and 5, and in a feather sample from a day-old chick. Escherichia coli was identified in all chicken samples. Salmonella spp. were found in the yolk samples at six out of nine farms (66.7%), whereas S. aureus was isolated from 17 of 18 feather samples (99.4%). The presence of these enteric bacteria and S. aureus on the environment and equipment surfaces indicated that microorganisms from the previous flock persisted despite thorough cleaning and disinfection. This residual contamination indicated that bacteria persisted mainly during the broiler cycle due to insufficient environmental sanitation and the presence of already infected chickens. The current results demonstrated that existing disinfection methods are insufficient to protect newly stocked flocks. These findings underscore the need for improved hygiene standards to reduce the prevalence of zoonotic pathogens in poultry production.