title: Investigation of in-feed organic acids as a low cost strategy to combat Salmonella in grower pigs.
abstract: Salmonella carriage in pigs is a significant food safety issue. Dietary supplementation with organic acids has previously been shown to reduce shedding and transmission of Salmonella. Therefore, this study aimed to examine the effect of three commercially available organic acid-based products on Salmonella levels in grower pigs, using a model of experimental infection that closely mimics natural exposure to the organism. Seven week old trial pigs (n=40) with a mean weight of 14.7kg were placed in one of four pens with 10 pigs/pen. Pens had previously been contaminated with Salmonella Typhimurium 4,[5],12;i;- via seeder pigs. Trial pigs received one of four diets for 28days: 1, control diet; 2, sodium butyrate supplemented diet; 3, benzoic acid supplemented diet and 4, formic-citric acid supplemented diet. A further 10 pigs were placed in a Salmonella-free pen receiving the control diet. Pigs were weighed and blood sampled on days 0 and 28. Faeces was collected on day 0, 2, 3, 5, 7, 14, 21 and 28 and examined for Salmonella. On day 28, 5 pigs/group were euthanised and ileocaecal lymph nodes (ILN) and caecal contents sampled for culture. The remaining 5 pigs/pen were then fed the control diet and faeces were collected on days 35 and 42. On day 42 pigs were euthanised and ILN and caecal contents tested for Salmonella levels. The trial was repeated once. Within the first two days of exposure to the contaminated environment, 96% (77/80) of pigs became infected. Most pigs shed Salmonella at levels of between 100-103CFU/g faeces for at least 7days post-exposure. A significant reduction in Salmonella faecal concentration was observed after supplementation with sodium butyrate (p=0.001) and a formic citric acid blend (p<0.0001). Average daily weight gain (ADWG) was significantly increased in all groups fed the supplemented feed when compared to the positive control group. The use of sodium butyrate or a blend of formic and citric acid in feed could be considered a cost-effective control measure to reduce Salmonella faecal shedding and improve ADWG in Salmonella infected herds.
authors.affiliation: National Food Research Centre, Teagasc, Ashtown, Dublin, Ireland; UCD Veterinary Sciences Centre, University College Dublin, Dublin, Ireland. Electronic address: Lynchhelen28@gmail.com.
authors.forename: H
authors.initials: H
authors.lastname: Lynch
authors.affiliation: UCD Veterinary Sciences Centre, University College Dublin, Dublin, Ireland.
authors.forename: F C
authors.initials: FC
authors.lastname: Leonard
authors.affiliation: National Food Research Centre, Teagasc, Ashtown, Dublin, Ireland; Department of Science, Waterford Institute of Technology, Waterford, Ireland.
authors.forename: K
authors.initials: K
authors.lastname: Walia
authors.affiliation: Pig Development Department, Teagasc, Moorepark, Fermoy, Co. Cork, Ireland.
authors.forename: P G
authors.initials: PG
authors.lastname: Lawlor
authors.affiliation: National Food Research Centre, Teagasc, Ashtown, Dublin, Ireland.
authors.forename: G
authors.initials: G
authors.lastname: Duffy
authors.affiliation: UCD Veterinary Sciences Centre, University College Dublin, Dublin, Ireland.
authors.forename: S
authors.initials: S
authors.lastname: Fanning
authors.affiliation: UCD Veterinary Sciences Centre, University College Dublin, Dublin, Ireland.
authors.forename: B K
authors.initials: BK
authors.lastname: Markey
authors.affiliation: Department of Agriculture, Food and the Marine, Central Veterinary Research Laboratory, Backweston, Ireland.
authors.forename: C
authors.initials: C
authors.lastname: Brady
authors.affiliation: Department of Science, Waterford Institute of Technology, Waterford, Ireland.
authors.forename: G E
authors.initials: GE
authors.lastname: Gardiner
authors.affiliation: National Food Research Centre, Teagasc, Ashtown, Dublin, Ireland.
authors.forename: H
authors.initials: H
authors.lastname: Argüello
mesh_terms: D000704:Analysis of Variance; D000821:Animal Feed; D000818:Animals; D057138:Bacterial Shedding / Q000187:drug effects; D019817:Benzoic Acid / Q000008:administration & dosage; D020148:Butyric Acid / Q000008:administration & dosage*; D002432:Cecum / Q000382:microbiology; D019343:Citric Acid / Q000008:administration & dosage*; D019587:Dietary Supplements; D037901:Euthanasia, Animal; D005243:Feces / Q000382:microbiology; D005561:Formates / Q000008:administration & dosage*; D011897:Random Allocation; D012481:Salmonella Infections, Animal / Q000097:blood / Q000517:prevention & control*; D012486:Salmonella typhimurium / Q000302:isolation & purification; D013552:Swine; D013553:Swine Diseases / Q000097:blood / Q000382:microbiology / Q000517:prevention & control*; D015430:Weight Gain
chemical_list: D005561:Formates; C030544:formic acid; D020148:Butyric Acid; D019343:Citric Acid; D019817:Benzoic Acid
keywords: Dietary supplementation; Monophasic Salmonella Typhimurium; Organic acid; Pig