Histology and histomorphometry of the tibia growth in two turkey strains.

Qualitative and quantitative histological methods on decalcified and undecalcified specimens were used for comparing the linear and radial growth of the tibia in two turkey strains: a light strain, Betina, without leg problems and a heavy strain, Maxiboul, with leg problems. Groups of 10 clinically healthy male turkeys of each strain were studied at 2, 6, 8, 16, and 20 weeks of age. Three histomorphometric parameters of longitudinal growth were quantitated in the proximal growth plate and metaphysis. These were: height of the proliferative zone, density of ossification buds (metaphyseal sprouts), and volume of metaphyseal trabecular bone. Four histomorphometric parameters of radial growth were quantitated in the diaphysis. These were cortical thickness, active zone/total surface, density of maturing osteons in the active zone, and bone apposition rate at the maturing primary osteons level. The results showed some evidence for factors predisposing to leg problems in the Maxiboul strain. At 8 weeks, the Maxiboul strain had a lower ossification bud density (13.1/mm2 vs. 20.7/mm2; P less than .05) and a lower metaphyseal trabecular bone volume (16.4% vs. 22.0%; P less than .05) when compared to the Betina strain. No difference was detected in the cortical thickness of the diaphysis in the two strains except at 2 weeks of age (799 microns vs. 387 microns; P less than .001), despite the heavier weight of the Maxiboul strain.

Picorna-like viruses of young turkeys: pathogenesis of a disease of poults caused by a picorna-like virus.

A strain of picorna-like virus cultivated in the yolk sac membranes of inoculated eggs was inoculated into 6-day-old turkeys. Clinical signs and mortality were observed between two and three weeks. Virus was seen in the faeces. The post-mortem and histological changes in the organs of infected birds were highly suggestive of a viral aetiology. The virus was reisolated from organs of sick and dead poults by inoculating SPF embryonated eggs.