Compared with unvaccinated challenged birds, day-old chicks vaccinated orally with live Salmonella typhimurium galactose epimerase mutant (G30D) and challenged orally after 14 days with a field strain of S. typhimurium had statistically significant reductions in fecal shedding (P less than 0.01), in salmonella carrier status at slaughter (P less than 0.05), in salmonella in the broiler-house environment (P less than 0.005), and in serological response in the fourth week after challenge (P less than 0.005). The vaccine did not elicit a serological response as measured by plate, microagglutination, and microantiglobulin tests. The vaccine had a significant depression on live-weight gain which was not apparent after 6 weeks. The vaccine did not significantly reduce live weight at 8 weeks below that of unvaccinated control birds. The field strain produced an 8% reduction in live weight at 8 weeks below that of controls. The potential role of vaccines in salmonella control, and economic losses due to salmonellosis, are discussed.
Two separate experiments were conducted to assess the shed rate and duration of shed of S . typhimurium organisms from turkey poults orally infected with chlortetracycline-sensitive S. typhimurium in relation to chloretetracycline (CTC) given in the feed at 0, growth promotant, subtherapeutic and therapeutic levels; the emergence of resistant S. typhimurium organisms in reference to the diet given; in vitro transfer of drug resistance from thses resistant S. typhimurium donor cultures to multiply-sensitive E. coli recipients; and phage type changes, is any, of these S. typhimurium isolates. The results showed that increasing CTC in the diet from 0 to the three levels of antibiotic supplementation, appeared to (a) reduce shed and duration of shed corresponding to each level used; (b) cause a minimal development of drug resistance and its transfer (usually at sub-therapeutic levels of CTC supplementation) for the duration of the experiment; and (c) induce phage type changes in some of the S. typhimurium isolates. These phage type changes question the validity of using phage typing as a tool in epidemiological investigations.
Antibiotic dipping with gentamicin sulfate by means of the temperature-differential method was effective in reducing but not completely eliminating Arizona hinshawii (7:1, 7, 8) from artificially infected turkey hatching eggs. Embryonic development was well maintained. The antibiotic dip solution intake was variable from egg to egg. Removal of cuticle by means of either 0.2 N HCl or a 10% disodium salt of ethylene diamine tetraacetic acid enhanced egg weight gains and maintained good embryonic development. Complete elimination of A. hinshawii was achieved in one experiment out of four. Correlation studies between egg weight gains and gentamicin concentrations of the contents of the turkey hatching eggs indicated a statistically significant relationship between these two parameters.
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