| Popis: |
WHETHER young chickens are more susceptible to coccidiosis than older birds is a question on which workers in this field have conflicting opinions. Some maintain that the younger the bird the greater its susceptibility, while others feel that very young chicks are comparatively immune (Becker, 1952). Horton-Smith (1947) has demonstrated that, provided the birds are kept free of infection, 6-month-old chickens are just as susceptible as younger birds. In regard to the effect on the host bird of the quantity of oocysts received, the prevailing idea seems to be that severity of infection is in direct proportion to number of oocysts ingested. Horton-Smith (1947) found a correlation between the quantity of oocysts ingested and the percent of mortality, the larger doses proving more fatal than the smaller. His largest inoculation was 120,000 sporulated oocysts per bird, but he does not state the age of the chicks when inoculated. Jones (1934), … |
