Effect of four antibiotic additives on the Salmonella contamination of chicks protected by an adult caecal flora.
Avoparcin (10 mg/kg feed), bacitracin (50 mg/kg), flavomycin (5 mg/kg) and virginiamycin (20 mg/kg) were tested for their synergy or antagonism on the protective effect of an adult caecal flora administered to 1-day-old chicks. The chicks were challenged experimentally per os with 10(4) to 10(5)Salmonella typhimurium (a rifampicin-resistant strain) when aged 2 days. Chicks receiving avoparcin continuously in the feed had significantly more Salmonella in their caeca than control birds given feed containing no antibiotics; those receiving flavomycin had similar numbers to the controls whereas the groups fed on a diet supplemented with bacitracin or virginiamycin exhibited the lowest level of Salmonella carriage.
Humbert
F
F
Centre National d'Etudes Veterinaires et Alimentaires, Laboratoire Central de Recherches Avicole et Porcine, Ploufragan, France.
Lalande
F
F
L'hospitalier
R
R
Salvat
G
G
Bennejean
G
G