Percloacal infection of chickens with Salmonella typhimurium

The characteristics of Salmonella typhimurium infection in hatchlings and adult poultry given by the intravenous, oral and percloacal routes were compared. Based on LD₅₀ determinations, 1-day-old birds were most susceptible to percloacal infection. It is claimed that this infection technique yields predictable results in terms of mortality and numbers of organisms in the liver, spleen and intestinal tissues. Though older birds do not die when given large doses of organisms by this route, small numbers are sufficient to establish transient infection or carriage in the intestine.Based on quantitative data, the course of the percloacal infection appeared similar to that given by the oral route in hatchlings; however, the number of organisms required to establish infection by the former route was significantly less. It is suggested that the percloacal infection route may be a useful model for studying Salmonella infection-immunity in birds, particularly if resistance mechanisms operating in the intestine are to be taken into account. The possibility that it may be an important infection route in natural circumstances must also be considered.     

The transfer from ewe to lamb of clostridial antibodies

Abstract Extract Many farmers in New Zealand find it necessary to vaccinate their sheep flocks against certain of the clostridial diseases. Effective vaccines are available to protect sheep against the major scourges of blackleg, enterotoxaemia (pulpy kidney), malignant oedema, tetanus and black disease, but, to secure the full protective potential of each vaccine, it must be applied in the optimum fashion. This means using a potent vaccine, correctly administered to responsive sheep at such time before exposure that protection will have reached its peak when the challenge is encountered. It is generally accepted that such an ideal set of circumstances is only rarely achieved in the field.