BACKGROUND: Vitamin C is one of the important nutrients in fish culture and as a potent anti-oxidant, is of great importance in preserving cells against oxidation and boosting resistance in stress conditions and against pathogens. OBJECTIVES: The purpose of the present study is to add high level of vitamin C supplementation to rainbow trout (Oncorhynchus mykiss) diet reared at high density and analysis of growth indices, survival and carcass composition at two different stocking densities. METHODS: Rainbow trout juveniles with initial body weight of 9.6 ± 0.69 g at two densities of 50 and 100 pieces in 50 liters of water were fed two diets containing the same level of protein and fat. Experimental diets were diet 1 without adding vitamin and diet 2 with adding 1500 mg/kg of vitamin C. A total number of 900 rainbow trout juveniles in four treatments each with three replicates as T50 (0) (with the density of 50 and fed with diet 1), T100 (0) (with the density of 100 and fed with diet 1), T50 (C) (with the density of 50 and fed with diet 2) and T100 (C) (with the density of 100 and fed with diet 2) were randomly distributed in incubators. RESULTS: After 6 weeks of feeding, growth indices, feed conversion ratio and viability were significantly different between treatments (p<0.05). T50 (0) and T50(C) treatments had higher weight gain, specific growth rate and viability than T100 (0) and T100(C) (p<0.05). In the case of feed conversion ratio, it was higher in T100 (0) and T100(C) treatments compared to T50 (0) and T50(C) ones (p<0.05). Carcass composition was not significantly different between treatments (p>0.05). CONCLUSIONS: The results showed that vitamin C supplementation in the diet of rainbow trout juveniles did not have significant effects on growth indices, feed conversion ratio, survival and carcass composition but density was a key factor in growth, feed conversion ratio and survival in this species.

OBJECTIVE To determine pet-related management factors associated with the carriage of antimicrobial-resistant Salmonella spp and Escherichia coli in a population of pet dogs. SAMPLE 138 dogs from 84 households in Ontario, Canada. PROCEDURES From October 2005 through May 2006, dogs and households in Ontario, Canada, were recruited to participate in a cross-sectional study. Fecal samples were submitted for culture of Salmonella spp and E coli, which provided 515 bacterial isolates for antimicrobial susceptibility testing. Multilevel logistic regression models with random effects for household and dog were created to identify pet-related management factors associated with antimicrobial resistance. RESULTS Bacterial species, feeding a homemade diet or adding homemade food to the diet, feeding a raw diet or adding anything raw to the diet, feeding a homemade raw food diet, and feeding raw chicken in the past week were significant risk factors for antimicrobial resistance in this population of dogs. CONCLUSIONS AND CLINICAL RELEVANCE In this study, several potentially important pet-related risk factors for the carriage of antimicrobial-resistant Salmonella spp and E coli in pet dogs were identified. Further evaluation of risk factors for antimicrobial resistance in dogs may lead to development of evidence-based guidelines for safe and responsible dog ownership and management to protect the public, especially pet owners who are immunocompromised.

OBJECTIVE To evaluate the effects of dietary nonphytate phosphorus (NPP) content on ileal lymphocyte subpopulations and cytokine expression in the cecal tonsils and spleen of hens that were or were not inoculated with Salmonella Typhimurium. ANIMALS 64 Salmonella-free hens. PROCEDURES Hens were fed a diet with 0.22% (control; n = 32) or 0.42% (high-P; 32) NPP for 6 weeks and then orally inoculated with S Typhimurium (5 × 107 CFUs) or PBSS. Tissues were obtained from 8 S Typhimurium–inoculated and 8 PBSS-inoculated hens from each group at 2 and 7 days postinoculation (DPI). Percentages of ileal CD4+ and CD8+ lymphocytes were determined by flow cytometry. Cytokine mRNA expression was determined by quantitative real-time PCR assays. RESULTS For S Typhimurium–inoculated hens, plasma parathyroid hormone concentration was significantly increased and 1,25-dihydroxyvitamin D3 concentration was decreased in hens fed the high-P diet, compared with values in hens fed the control diet. Salmonella Typhimurium inoculation caused an increase in the percentage of ileal CD8+ lymphocytes and the expression of interleukin (IL)-1β, IL-6, IL-8, interferon-γ, IL-12, and IL-18 in the cecal tonsils and spleen and a decrease in the expression of IL-4 and IL-10 in the cecal tonsils. Hens fed the high-P diet had significantly increased splenic expression of interferon-γ at 2 DPI and IL-1β, IL-6, IL-12, and IL-18 at 7 DPI, compared with hens fed the control diet. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested there was a T-helper 1 cytokine reaction in the cecal tonsils and spleen of S Typhimurium–inoculated hens, and dietary NPP content altered calcium regulation hormone concentrations and affected splenic cytokine expression.