Impact of Poultry Age, Season, Litter Quality, and Nutritional Intervention Strategies on Salmonella Prevalence and Populations, Serotypes, Genotypes, and Antibiotic Resistance Profiles

SANTOS, FERNANDA BOTARO DE OLIVEIRA. Impact of poultry age, season, litter quality, and nutritional intervention strategies on Salmonella prevalence and populations, serotypes, genotypes, and antibiotic resistance profiles. (Under the direction of Drs. Brian Sheldon and Peter R. Ferket). Poultry-related salmonellosis is an on-going problem that the poultry industry must continue to address. To address these challenges, Salmonella populations present on litter and fecal samples of brooder and grow-out turkey farms were assessed using a quantitative procedure. Furthermore, serotyping, genotyping by pulsed-field gel electrophoresis and antibiotic resistance-susceptibility analyses were used to investigate the diversity of the Salmonella serotypes present on these farms. Additionally, alternative on-farm pathogen intervention strategies including feeding whole or coarsely ground grains, increasing insoluble fiber content of the diet and use of an alternative non-litter cage-based housing design (Broilermatic System) were evaluated. Salmonella litter populations averaged 2 logs higher in 3-wk turkey samples compared to samples from 19-wk birds. Turkey age also influenced Salmonella serotypes, genotypes and antibiotic resistance profiles. Only serovars Javiana and Mbandaka were common between 3 and 19-wk old turkeys. A higher frequency of multidrug resistance was observed in Salmonella isolates recovered from samples of 3-wk birds, on average isolates were resistant to >4 antibiotics tested. Supplementing coarse ground corn and increased insoluble fiber (wood fiber) content into the turkey diet did not adversely impact body weights. However, the treatments did not influence Salmonella colonization or fecal shedding of turkeys. To examine the impact of housing design and addition of whole or coarsely ground grains on performance, intestinal microbial diversity and Salmonella colonization, broilers were reared on four diets consisting of finely or coarsely ground corn and finely ground or whole triticale to market age and Salmonella populations measured. Whole grain supplementation decreased Salmonella cecal populations while rearing broilers on litter floor as opposed to the Broilermatic System resulted in significant reductions in Salmonella cecal populations. Moreover, feeding whole triticale presumably encouraged the proliferation of bacterial populations which may have competitively excluded Salmonella in the ceca of broilers. In conclusion, highly variable Salmonella populations and serotypes were detected across all commercial turkey farms and the use of alternative feed ingredients such as triticale may help to reduce Salmonella colonization in poultry. Moreover, diet composition and grain coarseness as well as housing design can influence the diversity of the commensal intestinal microflora which may help in the control of Salmonella colonization in broiler intestines. IMPACT OF POULTRY AGE, SEASON, LITTER QUALITY, AND NUTRITIONAL INTERVENTION STRATEGIES ON SALMONELLA PREVALENCE AND POPULATIONS, SEROTYPES, GENOTYPES, AND ANTIBIOTIC RESISTANCE PROFILES