The influence of dietary protein and antimicrobial feed additives on salmonella carriage by broiler chickens.

Salmonella carriage in broiler chickens was not apparently influenced by the protein concentration of the ration, pelleting or by the coccidiostat monensin. The inclusion of penicillin in the diet was associated with an increase in salmonella shedding, particularly in the first half of the rearing period, but did not influence the lactobacillary count in the crop or the pH of the contents of the crop, gizzard and caecum. Furazolidone medication (150 mg/kg food) for the first 10 days had no effect on salmonella carriage at the time of slaughter (seven weeks) and studies into the influence of growth promoting antibiotics (avoparcin, bacitracin and virginiamycin) on salmonella shedding were inconclusive. Circumstantial evidence indicated that the food was the most probable source of infection for the birds studied in these experiments.