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Summary An isolator is described, fabricated in glass-reinforced plastic, suitable for housing 25–30 chicks to 6 weeks of age, or for fewer older birds, for use in experiments involving infectious agents.

1. Rhode Island Red females were fed, from hatching, on diets which had been fumigated with methyl bromide at the concentration recommended for the elimination of salmonellae or at 1 1/2 times this value. 2. Body weight, egg weight or egg number were not significantly affected by treatments, but sexual maturity may have been slightly delayed. 3. There was some evidence of an adverse effect on egg flavour, particularly by the trained sensory panel. 4. Principles of experimental design for this type of experiment are discussed.

1. Broilers were fed on control and treated commercial diets to test the effects of fumigation with methyl bromide gas at 69% and 25% over the value recommended for the elimination of salmonellae. 2. A trained sensory panel found significant taint in roasted meat from birds fed on the fumigated food. More than half of the consumers in the home panel rated the control birds better than the birds fed on the fumigated food. 3. Growth of broilers was not affected by the treatment.

Synopsis The sporicidal activity of a solution of phenylmercury dinaphthylmethane disulphonate (PMDD) containing between 11 and 13 p.p.m. mercury was proved both in the laboratory and in field finals. It is suggested that PMDD is suitable for the control of egg transmitted aspergillosis.

Synopsis Plastic tent isolators for the reaning and maintenance of chickens from day‐old to 80 weeks of age free from a number of pathogens have been evaluated. The use of individual ventilation units for each isolator has been compared with a central plant capable of supplying several isolators and has been found to be more efficient and have lower running costs.

Summary The incubator is used in conjunction with isolators for rearing specified-pathogen-free chicken. It can hold 30 eggs each of 56 g weight.

The ceca of newly hatched chicks obtained either from commercial hatcheries or from a carefully controlled experimental hatchery have been shown to contain high numbers of a variety of microorganisms. Fecal streptococci, clostridia, enterobacteria, pediococci, and occasionally Pseudomonas aeruginosa have all been isolated, but never lactobacilli. After the chick has been on feed for 1 day, the numbers of lactobacilli in the crops and ceca are quite variable; by the 3rd day, however, large numbers are present throughout the alimentary tract. Lactobacilli could be established after 1 day by incorporating them in the feed or by treating the chicks with 0.5 ml of a broth culture. Spraying the eggs before hatching did not lead to their early establishment. Lactobacilli given alone to the newly hatched chick failed to prevent the establishment of Salmonella. However, when the chicks were given a complex mixture of facultative anaerobes and anaerobes which had been isolated from an adult bird, cecal colonization with Salmonella was prevented. The possible importance of the facultative anaerobes, particularly Streptococcus faecalis, in lowering the redox potential to encourage the growth of the anaerobes is discussed.

A method of 'rearing and maintaining chickens from day old to 80 weeks of age free from infectious bronchitis, Newcastle disease, infectious avian encephalomyelitis, CELO and GAL viruses, lymphoid leukosis, Marek's disease, Mycoplasma gallisepticum, Salmonella pullorum and other Salmonella spp., Staphylococcus aureus, Eimeria spp. and helminths is described. The advantages of glass fibre isolators each with its own ventilation system are outlined.

The free amino acids occurring in alcoholic extracts of fowl seminal plasma have been examined by filter-paper chromatography. Twenty-three have been detected consistently, and these include several that have not been hitherto reported in the seminal plasma of the domestic fowl. In addition, several unknown ninhydrin-reacting substances have been found. Glutathione and ergothioneine were not detected in the volumes of plasma chromatograhed. There was evidence of the presence of glycocyamine and an unknown imidazole compound.