SPECIAL STORY FEED & ADDITIVE MAGAZINE September 2022 43 POULTRY AND SALMONELLA: A COMMON PROBLEM Salmonella is regularly found in the poultry microbiome. There are over 2,500 variants (serotypes) associated with poultry, with very few causing illness in poultry and more causing illness in humans. When testing poultry flocks and food products for Salmonella, serotyping is important because it tells you if flocks contain Salmonella that can cause harm to humans. Usually, Salmonella contamination starts with a bird consuming contaminated feed, debris or fecal material (Chadwick, 2017). Salmonella can colonize in multiple locations throughout the poultry gut and, if there is damage or stress to the gut, it can move into circulation and colonize in other internal organs (Martha Pulido-Landínez, 2019). It will compete with the native gut microbiota for colonization sites and food sources. Once colonized, it can replicate and move throughout the digestive tract, being found from crop to the ceca. The lining of the poultry gut is shed every few days, so Salmonella is shed in the feces to the rest of the flock. In laying hens raised in cages, there is concern with vertical transmission of Salmonella from the parent to the egg. In laying hens raised in cage-free/free-range systems as well as meat birds, vertical and horizontal transmission (between flock members) is of concern. Ensuring all the Salmonella entry points throughout the production process--the feed and drinking water, breeding birds, the hatcheries, the broiler or laying hen farms and the processing facilities--are controlled, checked and regulated is necessary. SALMONELLA IN THE FEED AND DRINKING WATER Feed comprises 70% of poultry production costs, thus efficient and sustainable utilization of feed ingredients and related resources is paramount to have the lowest possible feed cost with the least feed material waste. Salmonella contamination risk increases due to ingredients coming from multiple locations, and cross contamination in feed can derive from crop harvest, feed processing, transportation, and storage (Chadwick, 2017). Monitoring feed ingredients in the poultry diet that are Salmonella carriers, like protein and vegetable sources, can help reduce the risk of contamination. Feed mill equipment must also be regularly cleaned to reduce cross contamination (Martha Pulido-Landínez, 2019). Feed hygiene in combination with water sanitation practices can help control which bacteria are consumed by the flock. One of the most effective feed hygiene strategies, addition of formaldehyde, can no longer be used in multiple countries due to regulatory restrictions. Chlorination and acidification treatments have been used in water to reduce bacterial populations. Organic acids are typically used for both feed as well as drinking water, which act by damaging the Salmonella bacterial cell wall due to their antimicrobial activity, reducing the amount of Salmonella in the feed that can colonize in the bird’s gut (Hajati, 2018).
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