No abstract

Male broiler chicks were grown at cold temperatures to enhance susceptibility to the ascites syndrome. Various feeding regimens were used to determine whether they could influence mortality due to ascites. It was found that a precisely controlled early feed-restriction regimen at the age of 6 to 11 days significantly reduced mortality from all causes and mortality due to ascites, while maintaining optimum body weight and feed conversion at marketing age.

In the present study, we wished to demonstrate the ability of surface gametocyte antigens to induce protective immunity against Eimeria maxima infections in chickens. In order to accomplish this goal, we employed maternal immunization as a means of providing large amounts of specific antibodies to offspring chicks. Upon challenge with sporulated E. maxima oocysts, chicks from hens immunized with affinity-purified gametocyte antigens showed greatly reduced oocyst production compared with chicks from sham-immunized hens. These results suggest that maternal immunization with gametocyte antigens can be used as a means to provide transmission-blocking immunity against E. maxima infections.

SUMMARYThe effects of type of feed, ambient temperature and ventilation were investigated on a fastgrowing strain of broiler under conditions conducive to the induction of the ascites syndrome. Parameters used to monitor the syndrome were the erythrocyte packed cell volume (PCV), and the ascites heart index (AHI) which is a measure of the hypertrophy of the right ventricle; both these parameters are elevated in birds suffering from the syndrome.It was found that ventilation had no role in the syndrome. Sex of the bird was not correlated with PCV or AHI values. Low ambient temperatures caused rapid and significant rises in PCV, and some rise in the AHI. Pelleted feed, in comparison with the same feed in mash form, was shown to cause significant elevations in the AHI, but little change in the PCV. Suitable husbandry can therefore, minimize physiopathological changes in the chickens which may later progress to a fatal ascites.

Outbreaks of neoplastic disease defined as haemangiosarcoma occurred among layer flocks of chickens in Israel. The disease caused bleeding tumours in the skin and internal organs of young layers, followed by anaemia, cessation of egg production and high mortality up to 20%. Avian leukosis virus was isolated from tumour cells which contain several viral DNA copies integrated in the cell genome. The isolated virus induced haemangiosarcomas in more than 30% of birds inoculated on the day of hatching. Congenital transmission of viruses from tumour-bearing hens to their offspring was observed.