Survival and clearance dynamics of Salmonella in litter, carcasses, and internal organs of chickens fed different dietary fat sources.

Abstract

The study evaluated the efficacy of four different fat sources in broiler feed on Salmonella presence in litter, spleen, liver, ceca, and carcasses. In this study, 1152, day-old chicks were allocated into four different treatments randomized among 48 pens. Fat source-based treatments included Soy Oil (T1), Poultry Fat (T2), Soap Stock (T3), and Palm Oil (T4). All birds were orally challenged on day 7 with 10^8 CFU of S. Enteritidis and S. Typhimurium cocktail. On days 14, 21, 28, 35, and 42, litter was sampled from each pen using boot swabs and spleen, liver, and cecal contents were sampled from one bird from each pen for Salmonella recovery. On day 43, 16 post-pick carcass rinsates per treatment were collected for Salmonella recovery. Data was analyzed using PROC GLM of SAS and Chi-square test in R. On day 14, Salmonella was detected from 16 %, 25 %, 41 %, and 33 % of spleen and 83 %, 66 %, 50 %, and 75 % of liver samples from T1, T2, T3, and T4, respectively (P > 0.05). Salmonella prevalence decreased in liver to 0 % at day 42 in all treatments except for 1 liver from T1. At day 14, cecal contents were 92 %, 83 %, 92 %, and 92 % Salmonella positive for T1, T2, T3, and T4 with an average of 3.5 to 4.6 logCFU/g. However, by day 42, Salmonella was not detected by direct plating in cecal contents and prevalence decreased to 25 %, 45 %, 42 %, and 25 % from T1, T2, T3, and T4, respectively. Post-pick carcass rinses were 100 %, 100 %, 100 %, and 81 % positive from T1, T2, T3, and T4, respectively. No significant differences in Salmonella counts or prevalence were observed among different dietary fat source treatment groups. These results indicate that the clearance pattern of Salmonella from internal organs over time was not influenced by fat sources. Although internal Salmonella contamination appeared to have mostly cleared by day 42, the continued presence and survival of Salmonella in the litter may have resulted in post-pick carcass contamination.