[Physiological variables in calves and their significance for vitality and growth]. / Physiologische Variablen bei Kälbern und ihre Bedeutung für Vitalität und Wachstum.

Calves from the dairy herd and from the mother cow herd and their dams were investigated just after parturition and the calves at the first two days of life and between fifteen and twenty days and than at ninety days of life as well using whole day heart rate and video recording, results of venous blood sample analysis and body growth and health criteria. The great variation of physiological variables in calves can partly be explained by maturity, degree of adaptation, gender, time of day and the birth course. Relationships between physiological variables and the adaptability, body growth performance and the degree of adaptation to specific rearing condition could be pointed out.

Immunological responsiveness of Pekin ducks to core antigen of duck hepatitis B virus.

Cellular immune responses to the HBc or HBe antigen of hepatitis B viruses contribute to the pathogenesis of hepatitis B and to the elimination of the virus. Insufficient cytotoxic immune reactions against the core antigen may be one major reason for viral persistence in the absence of severe clinical symptoms. We attempted to stop viral persistence in the animal model of congenitally infected ducks by injection of recombinant DHBc particles, together with the strong immunostimulator Freund's adjuvant. However, the duck HBc antigen (DHBcAg)-treated ducks did not develop detectable liver disease, nor was the virus persistence affected. The congenitally infected ducks did not contain antibodies against DHBcAg before injection despite continuous production of duck hepatitis B virus, and developed only a weak transient antibody response after injection of recombinant DHBcAg together with Freund's adjuvant. Noninfected ducks developed, in contrast, a strong antibody response to the injected DHBcAg. We conclude that congenitally infected ducks are immunotolerant to DHBcAg and cannot be cured by immunotherapy with exogenous recombinant DHBcAg.