An outbreak of highly pathogenic avian influenza in Australia in 1997 caused by an H7N4 virus.

In November of 1997 an outbreak of highly pathogenic avian influenza occurred near the town of Tamworth, in northern New South Wales, Australia. The viruses isolated from chickens on two commercial chicken farms were identified as H7N4 viruses, with hemagglutinin cleavage site amino acid sequences of RKRKRG and intravenous pathogenicity indices of 2.52 and 2.90, respectively. A virus with an identical nucleotide sequence, but with an intravenous pathogenicity index of 1.30, was also isolated from cloacal swabs collected from asymptomatic emus kept on a third property.

Successful treatment of mycoplasmosis in layer chickens with single dose therapy.

The efficacy of treatment with single dose administration of 5 drugs at different dosages to layer hens naturally infected with Mycoplasma gallisepticum was studied. The drugs were tiamulin, which was administered orally, tylosin (parenterally and orally), spiramycin (orally), long-acting oxytetracycline (parenterally) and tylosindihydrostreptomycin (parenterally). Cure was assessed by the absence of nasal discharge. The cure rate was significantly higher (P less than 0.05) in treated hens than in untreated hens, as early as 1 day after treatment. Remission for 33 days was achieved in 60% of hens treated with 100 mg oxytetracycline, in 100% of hens treated with 100 mg or 200 mg spiramycin, in 92% and 85% of hens treated with 100 mg tylosin, parenterally and orally, and in 89% and 88% of birds given 100 mg tiamulin and tylosin-dihydrostreptomycin, respectively.

Production, hatchability and fertility of eggs from breeding Japanese quail (Coturnix coturnix japonica) fed diets containing furazolidone.

1. Breeding Japanese quail were allocated to 8 groups, each group consisting of 20 females and males. The birds were fed one of 4 diets for up to 33 d: a control diet or a diet containing 200 mg/kg, 400 mg/kg or 1000 mg/kg furazolidone. Subsequently, quails were fed a furazolidone-free diet for up to 21 d. Egg production, quality, hatchability and fertility of the groups were measured. 2. Significant reduction in egg production occurred in birds fed 400 mg/kg and 1000 mg/kg furazolidone, the effect being more pronounced at the higher concentration. 3. Hatchability was reduced significantly for all groups of birds fed furazolidone and this effect was both dose and time dependent. The reduction in hatchability was attributable to an increase in infertile eggs rather than an increase in embryonic mortality. 4. Egg quality was affected, with more small eggs being produced by birds fed 1000 mg/kg furazolidone. 5. After removal of the experimental diets egg production of the affected groups returned to control values. Hatchability and fertility of affected groups also returned toward control values, but had generally not attained these values 21 d after the cessation of the experimental diets. 6. It was concluded that standard recommendations for the therapeutic dosage of poultry with furazolidone may not be appropriate for breeding Japanese quail.