TUCKER, GA. — Researchers at the University of Georgia in Athens established a new gold standard for detecting and analyzing Salmonella in broilers and turkeys using advanced methods beyond traditional PCR culture. The US Poultry & Egg Harold E. Ford Foundation funded the study.

Led by principal investigator Nikki Shariat, PhD, the project had two objectives. The first was to determine the best live production sampling method for Salmonella detection and enumeration in broilers and turkeys. The second objective was to develop a recommended sampling strategy, including a timeline for collection, which correlates pre-harvest Salmonella with pre-intervention, post-harvest Salmonella.

In recent years, federal regulators have shown interest in pre-harvest monitoring. And while the study offers improved tools for assessing live-production interventions, it also highlights the issue of linking Salmonella presence before and after harvest — especially in turkeys — underscoring the challenges of implementing effective pre-harvest monitoring systems.

Work on the first objective found that, in broilers, traditional boot socks and boot socks wrapped around a roller were the most effective sampling methods for detecting and enumerating Salmonella.

“In turkeys, boot socks outperformed other methods for determining Salmonella prevalence and enumeration,” according to the study.

Findings for the second objective demonstrated that carcass rinses provided more reliable quantification data; however, mitts allowed the recovery of more serovars in chickens.

“The most abundant serovar detected at hot rehang was always detected at pre-harvest (collected 14 days before harvest); however, they were not always the most abundant serovar,” the study said. “Moreover, there were additional serovars found at processing that were not detected on the farm.”

In turkeys, researchers found that placement is the most reliable point for capturing high Salmonella loads and detecting environmental presence. Additionally, pre-harvest testing had the lowest sensitivity, with minimal detection and low quantifiable loads.

“This raises concerns about using seven-day pre-harvest testing alone as a surveillance time point,” the study noted. “Paw and vent samples collected at harvest (pre-scald) showed a resurgence in detection. There was little concordance in serovars detected on-farm with serovars detected at pre-scald.

“The discordance in Salmonella detection, load and serovars may be linked to increased bacterial shedding due to transport stress, feed withdrawal, or cross-contamination at catching and handling or lairage.”

The short-term benefit to the industry is an improved method for assessing Salmonella on the live side of turkey and chicken production, the study said. However, researchers demonstrate that, for both broilers and turkeys, connecting Salmonella prevalence, load and serovar between pre-harvest and post-harvest is complex.

“Reduction of Salmonella is a key focus for the broiler and turkey industries,” the US Poultry Foundation said. “Recent advancements in PCR-based methods have improved the ability to quantify Salmonella, but the challenge of reproducibility between samples has demonstrated that the former best practice pre-harvest sampling approaches must be re-evaluated.

“There is a critical need to identify a reproducible, affordable and feasible (i.e., can be reliably performed by service technicians) sample type to serve as an industry standard sample for accurately identifying Salmonella load on a flock level. Certain Salmonella serovars are more frequently linked with foodborne illness and there is a need to identify a pre-harvest sample type that can best reflect the serovars that are found at processing.”