|Cox, Nelson - Nac|
Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/24/2004
Publication Date: 7/27/2004
Citation: Rolon, A., Bailey, J.S., Holt, P.S., Hofacre, C.L., Wilson, J.L., Cosby, D.E., Richardson, L.J., Cox, Jr., N.A. 2004. Salmonella vaccination programs in broiler breeders. II. Resistance to challenge under a multiple marker strain model [Abstract]. Poultry Science. 83(S1):146. Interpretive Summary:
Technical Abstract: Resistance to Salmonella challenge of breeders and their chicks under three vaccination programs was assessed. Vaccine protocols combined a live Aro-A Salmonella Typhimurium (ST) vaccine and an autogenous 3-serovar killed vaccine. Treatments combined: 2 live and 2 killed or 3 live and 1 killed vaccines delivered at 1 d and 3, 11 and 17 wk of age; 2 killed vaccines given at d 77 and 126; and a non-vaccinated control (C). Breeders were gavaged with 10(7) cells of a 3-strain cocktail (nalidixic acid resistant Salmonella Enteritidis (Nal-SE), rifampicin resistant Salmonella Typhimurium (Rif-ST) and ampicillan resistant Salmonella Thompson (Amp-STH)), at wk 3, 6, 10, 18 and 22. Chicks from eggs laid at wk 29, 34 and 40 of breeder age (BA) were challenged at one day-of-age. Chicks were divided in two groups per treatment, one given a commercial competitive exclusion culture (CE), and both were challenged with 10(7) cells of a Nal-SE + Rif-ST+Amp-STH cocktail and kept in isolation units for one and two wk. Ceca and Liver-Heart-Spleen (LHS) samples were cultured for each marker strain on BGS + antibiotic (Nal, Rif, or Amp) plates and colonies counted after 24h incubation. Log10 data were analyzed under a factorial design. Breeder Salmonella counts showed significant differences between (live) vaccinates and non-vaccinates at 3 and 6 wk challenges. By 10 wk, there were no discernible difference in Salmonella level in challenge and control chicks, indicating protection by (1 d and 3 wk) live vaccines had diminished at this time. All programs reduced breeder Salmonella counts compared to controls at 22 wk. Chick Salmonella counts showed little consistency between vaccine treatments. At 34 and 40 wk BA, no difference was observed in susceptibility of chicks from vaccinated and control breeders. Passive immunity did not show consistent decrements on challenged chicks Salmonella counts. These results show that live vaccination with the Aro-A ST vaccination decreases Salmonella counts during the first 6 wk of age of the breeder, as do all programs by 22 wk of age, and that competitive exclusion is the most effective treatment in reducing Salmonella counts.