The effect of chick methionine status and methionine source on broiler performance and physiological response to acute and chronic heat stress

motile bacteria). Between the years 2008 and 2012, 140 samples from commercial poultry farms were collected in order to assay for Salmo­ nella. Thirty five Salmonella spp. (25%) were isolated from commer­ cial layers farms. Bacteria were isolated mainly from samples of liver and spleen (71.42%), pools of organs (liver, spleen and ovarian follicles (25.71%) and a lower proportion (2.85%) from drag swabs. Serotype was assigned using Intergenic Sequence Ribotyping (ISR). Sixteen Salmonella Enteritidis (SE), thirteen Salmonella Gallinarum (SG), and seven unique strains were found. Five unique strains were designated as UN0038, and the other two were designated as UN0052 and UN0054. DNA hybridization microarray assigned serovars Isangi, Branderup and Yoruba to the unique ISR sequences, respectively. This is the first report on the characterization of different serotypes of Salmonella pres­ ent in commercial layer farms in Colombia. The discovery that SE and SG could be isolated in the same time period, in similar commercial brown layer hens, and in different regions indicates it is important to investigate the dynamics of infection associated with the co-existence of zoonotic serotypes, such as SE, and species specific serotypes, such as SG, circulating within the same ecological niche. Programs that aim to monitor and control infectious disease affecting people and the foods they consume will benefit from this information.