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The effect that breeder-flock immune status regarding the infectious bursal agent (IBA) and two avian adenoviruses (DPI-1 and DPI-2) has on the susceptibility of their commercially reared Delmarva broiler progeny to the hemorrhagic-aplastic-anemia syndrome and concurrent gangrenous dermatitis was determined. Lack of immunity to the IBA in breeder flocks was related to an increased susceptibility of progeny to anemia and dermatitis. Breeder-flock immunity to the two adenoviruses tested could not be related to the resistance or susceptibility of their progeny to the hemorrhagic-aplastic-anemia syndrome and gangrenous dermatitis.

The serologic response of chickens to infectious bursal disease virus (IBDV) and inclusion body hepatitis virus (IBHV) was analyzed. Inoculation at one day old with either IBDV or IBHV significantly (P less than 0.05) reduced levels of serum gamma-globulins at 4 weeks postinoculation. This response was not elicited by inoculation of IBDV together with IBHV. Birds with experimentally induced or naturally occurring hemorrhagic anemia syndrome (HAS) had serum proteins quantitatively and qualitatively changed from those of controls. Serum protein profiles did not coincide, however, in experimentally infected and naturally infected chickens. Among naturally infected chickens, those that were IBHV-positive upon culture had significantly (P less than 0.05) lower hematocrit values.

Exposure to infectious bursal disease virus (IBDV) at 1 day old followed by inclusion body hepatitis virus (IBHV) inoculation at 36 days produced typical lesions of hemorrhagic-aplastic anemia syndrome (HAS). The lesions included severe anemia, widespread hemorrhages, and dermatitis. HAS could not be induced in the first 4 weeks of life in chickens inoculated at one day old with IBHV alone or in combination with IBDV. It was concluded that the immunosuppressive effects of IBDV failed to alter the pathogenicity of IBHV in chicks less than 4 weeks old. This resistance was considered to be age-related. Subcutaneous inoculation of day-old chicks with IBDV produced a more severe infection than did oral exposure. Serial passage of IBHV in day-old chicks had no significant effect on the viral pathogenicity.