A longitudinal field study of mortality and Marek's disease in Norwegian and imported white Leghorns.

High mortality during the first part of the laying period was observed in Norwegian White Leghorns during the period 1988-1992. A longitudinal field study with repeated measurement of cumulative mortality was undertaken in the period from January 1994 to January 1996 to investigate (1) the mortality and susceptibility to Marek's disease (MD) in the Norwegian strain (NB41) compared to two imported layers, (2) the effect of MD on the total cumulative mortality in the period from 16 to 32 weeks of age in White Leghorn flocks, and (3) the effect of MD as judged by repeated measurement of cumulative mortality in the same period. All five layer hatcheries and 67% of the pullet-rearing farms in Norway participated in the field study.

Pathological lesions in swine at slaughter. VI. The relation between some mainly non-environmental factors, diseases, weight gain and carcass quality.

The influence of some diseases (lesions at slaughter) on daily weight gain and the relation between some mainly non-environmental factors and diseases, weight gain and carcass quality were studied in 12 herds running an all in/all out fattener production. The material consisted of 9800 baconers slaughtered in the period 1975–1977. The piglets were purchased when about 10 weeks old.

Pathological lesions in swine at slaughter. V. Pathological lesions in relation to some environmental factors in the herds.

The influence of environment on animal health was studied in 40 bacon herds. These herds delivered approx. 11,000 baconers annually to the slaughter-house.