OBSERVATIONS ON A BROILER BREEDER FLOCK NATURALLY INFECTED WITH SALMONELLA-ENTERITIDIS PHAGE TYPE-4

Bacteriological and serological studies in a broiler breeder flock nat urally infected with Salmonella enteritidis indicated that the infecti on had become established by about 20 to 22 weeks of age. By 35 weeks, 70 per cent of the birds were positive by ELISA and at 39 weeks, 39 p er cent were estimated to be carrying the infection as judged by cultu re post mortem. By 50 weeks, post mortem culture showed 17 per cent to be infected and 85 per cent reacted to the ELISA. Over the period of observation at the laboratory, combined cloacal swabbing and post mort em culture showed that at least 12.5 per cent of the birds were carryi ng the infection and 95.7 per cent reacted serologically. As the level of infection apparently declined with age it may have been present at too low a level to detect in the unincubated eggs and newly hatched c hicks which were cultured. However, maternal antibody was present in 8 1 per cent of the eggs and 23 per cent of the chicks and it may have a ffected the colonisation of the organism and the ability to isolate S enteritidis.