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Aims:  The main aim of this study was to analyse the genetic relationship amongst 46 Staphylococcus aureus Bac+ strains isolated in Brazil from 12 geographically distant dairy herds, including 34 isolates that produce the antimicrobial peptide aureocin A70. Methods and Results:  The comparison of 46 Staph. aureus Bac+ strains was performed by pulsed‐field gel electrophoresis (PFGE). Thirteen different pulsotypes were identified, and the subtype A1 was the most prevalent one. Nine strains belong to pulsotype F, the second most prevalent and mostly confined to a single herd. The PFGE patterns of the 34 Staph. aureus aureocin A70‐producers, isolated in Brazil, were also compared with those of strains isolated from bovine mastitis cases in Argentina and revealed that these strains are not genetically related. Conclusions:  Although a previous study has suggested that a prevalent pulsotype of aureocin A70‐producer Staph. aureus involved in bovine mastitis is disseminated in Argentina, this does not occur in Brazil. Additionally, it was possible to demonstrate that closely related staphylococcal strains can produce distinct staphylococcins. Significance and Impact of the Study:  This study corroborates the hypothesis of horizontal gene transfer of aureocin A70 genes amongst distinct staphylococcal strains involved in bovine mastitis, giving them a selective advantage when colonizing the mammary glands.

RESUMO -Objetivou-se com o presente trabalho avaliar a utilização de manose como promotor de crescimento em dietas de suínos na fase de creche em alternativa ao uso de antibióticos. Avaliaram-se o desempenho, peso absoluto e relativo do fígado, pâncreas e baço, pH do conteúdo do estômago e ceco. Foram utilizados 160 leitões desmamados aos 21 dias de idade, sendo 80 machos castrados e 80 fêmeas, com peso médio de 6,2 kg (± 0,986 kg), em delineamento experimental em blocos ao acaso com cinco tratamentos, oito blocos e quatro leitões por unidade experimental. Os tratamentos consistiram de cinco rações, sendo uma com 25 ppm do antibiótico colistina (controle) e quatro rações com níveis crescentes de manose (0%; 0,02%; 0,10%; e 0,20%). As rações foram isonutrientes com 20% de PB e 3500 kcal de ED/kg de ração e foram formuladas para atender às exigências dos leitões nessa fase. Observouse que os tratamentos não influenciaram (P>0,05) o ganho de peso, consumo de ração, conversão alimentar e pH do conteúdo do estômago e do ceco, o mesmo ocorrendo com o peso absoluto e relativo do fígado, pân-creas e baço. Conclui-se que a inclusão de manose como promotor de crescimento às rações de leitões na fase de creche não melhorou o desempenho e não influenciou o peso dos órgãos e o pH do conteúdo do estômago e do ceco. TERMOS PARA INDEXAÇÃO:Antibiótico, desempenho, leitões, pH, prebiótico, órgãos. MANNOSE IN PIGLETS FEEDING IN THE NURSERY PHASE: (PERFORMANCE, pH OF THE GASTROINTESTINAL AND WEIGHT OF THE ORGAN)ABSTRACT -The present work was designed to evaluate the use of mannose as a growth-promoting additive for swine in nursery phase as an alternative to the use of antibiotics. The performance, relative weight of the liver, pancreas and spleen, pH of the stomach and cecum contents were evaluated. A hundred sixty (160) weaned piglets were utilized at 21 days old, 80 being castrated males and 80 females, weighing, on average, 6.2 kg (±0.986 kg) in an experimental randomized block design with five replicates, eight blocks and four piglets per experimental unit. The treatments consisted of five rations, one of the rations containing 25ppm of the antibiotic colistin (control) and four rations with growing levels of mannose (0 %; 0.02%; 0.10% and 0.20%). The diets were isonutrient with 20% of CP and 3.500 kcal of DE/kg of ration, they were formulated to meet the piglets' requirements in this phase. It was found that the treatments did not influence (P>0.05) gain weight, feed intake and feed conversion and pH of the stomach and cecum content. The same occurring with the absolute and relative weight of the liver, pancreas and spleen. It follows that the inclusion of mannose as a growth-promoting additive to the piglet diets in the nursery phase did not improve performance and did not influence the weight of the organs and pH of the stomach and cecum contents.