Location: Poultry Microbiological Safety and Processing Research UnitTitle: Evaluation of tris phosphate carbonate Salmonella pre-enrichment media for various ingredients and feed types
|CLAY, S - Anitox Corp|
|RICHARDSON, K - Anitox Corp|
|HOLCOMBE, N - Anitox Corp|
|WELLER, C - Anitox Corp|
|Cox, Nelson - Nac|
Submitted to: International Poultry Scientific Forum
Publication Type: Abstract Only
Publication Acceptance Date: 12/3/2019
Publication Date: 1/27/2020
Citation: Clay, S.M., Richardson, K.E., Holcombe, N.I., Weller, C.E., Cosby, D.E., Berrang, M.E., Cox Jr, N.A. 2020. Evaluation of tris phosphate carbonate Salmonella pre-enrichment media for various ingredients and feed types [abstract]. International Poultry Scientific Forum.
Interpretive Summary: N/A
Technical Abstract: Feed is a major source of Salmonella on poultry farms. Detecting Salmonella in feed is challenging due to its non-uniform distribution and it exists in a stressed state requiring resuscitation with pre-enrichment media. Studies have shown that pre-enrichment media lack the buffering capacity to prevent an acidic pH. Exposure of Salmonella to acidic conditions can result in cell injury, death or altered biochemical pathways preventing detection. A tris phosphate carbonate (TPC) pre-enrichment media has been developed to maintain a near neutral pH during incubation of feed. It has not been evaluated against a wide variety of feed and ingredients. Eight ingredient types and ten feed types were weighed out into 5g samples and individually placed into 45mL of different pre-enrichment broths: lactose broth (LB), buffered peptone water (BPW), double buffered peptone water (2xBPW), universal pre-enrichment broth (UPB), and TPC. Media were incubated for 0, 18, 24, and 48 hours at 37°C and the pH determined (five replicates/treatment). Data were analyzed by ANOVA and least significant difference T-test. For cereal grains and by-products, the initial pH of LB ranged from pH of 5.06 for DDGS to pH of 6.8 for sorghum. After 18 hrs of incubation, the pH had decreased to 4.4-4.6. Significant (p<0.05) decreases in pH were observed with longer incubation periods. BPW exhibited similar buffering capacity to that of LB. Although, 2xBPW and UPB were slightly better, the pH at 18-24 h was slightly acidic at 5.2-5.5. TPC maintained a near neutral pH during incubation. The pH of media containing vegetable protein meals decreased during incubation to pH 4.7-5.0 in LB and BPW, 5.1-6.0 in 2xBPW and UPB and 5.7-6.3 in TPC. The pH of media containing meat and bone meal was near neutral for all media. The pH of media containing poultry feeds had an initial pH of 6.5 to 8.4. After 24h incubation, the pH had decreased to 4.6-5.5 for LB and BPW. More variability was observed among feed types incubated in 2xBPW and UPB where the pH ranged from 4.8-6.4 at 24h. The pH of TPC varied less among feed types ranging from 6.5-7.4 at 24h. Results suggest that TPC is able to maintain a near neutral pH during pre-enrichment for a wide variety of ingredients and feed which can improve the ability to detect Salmonella.