Differential recoveries from faecal cultures of larvae of some gastro-intestinal nematodes of cattle.

Faecal cultures were established using bovine faeces containing known numbers of eggs from either Oesophagostomum radiatum, Haemonchus placei, Cooperia pectinata or a mixture of all three. A substantially greater percentage of larvae was recovered from cultures of O. radiatum and C. pectinata than was recovered from cultures of H. placei. The same pattern was observed in mixed cultures although yields of larvae from all species in mixed cultures were significantly reduced (p less than 0.001). The lower recovery of H. placei was not associated with a lower viability of H. placei eggs. Of the three different methods of harvesting larvae, the jar and mesh recovery technique was the least effective and significantly fewer larvae were recovered with this technique than with the Baermann and inversion techniques (p less than 0.05). The results are discussed with reference to the use of faecal culture and larval differentiation in the diagnosis of mixed species nematode infections of cattle.

The plasma cryofibrinogen of calves infected with Oesophagostomum radiatum.

A cryofibrinogen complex was detected in the plasma of cattle infected with Oesophagostomum radiatum. Its formation coincided with the development of hypofibrinogenaemia and it consisted basically of fibrinogen and soluble noncross-linked fibrin in both monomer and high molecular forms. Also present in the complex, albeit in trace amounts, were cold insoluble globulin, TgG, and plasminogen. It is suggested that the complex results from thrombin activation in vivo and its role is to maintain fibrin in solution thus preventing its deposition in the vascular system.

Age resistance of cattle to the nodular worm Oesophagostomum radiatum.

Two groups of seven castrated male calves, aged three and 13 months respectively, which had been reared worm-free, were infected with 5000 larvae of Oesophagostomun radiatum. At autopsy six weeks later a mean of 403 +/- 398 adult worms were recovered from the older animals and a mean of 1174 +/- 484 from the younger. This significant difference (P less than 0-01) indicates that the resistance of cattle to initial infection with O radiatum increases with age.