| risk factors for marek's disease and mortality in white leghorns in norway. | a prospective longitudinal field study was conducted in the period from january 1994 to january 1996 to analyse the relationship between some selected risk factors in the growing and laying periods and (1) the flock-level occurrence of marek's disease (md) during the period from 16 to 32 weeks of age and (2) the cumulative mortality during the same period. a total of 171 layer flocks in 102 egg-production farms were included in the statistical analyses.a logistic regression (with strain of layer ... | 2000 | 10760399 |