FIG. 1.

Frequency distribution of PCVs of the 286 cattle sampled (black bars) in comparison to PCV reference values (gray bars) determined in the Clinical Laboratory, University of Zurich. Reference values were determined by identical methods with blood samples from 49 healthy lactating Swiss cows ages 3 to 11 years. The 5% quantile of the PCV reference range is 25%, the median is 29%, and the 95% quantile is 33%. Fifty percent of the cows of the affected herd were anemic (PCVs < 25%). For further analysis, animals were categorized into severely anemic animals (group I), cows with intermediate PCVs (group II), and cows with normal PCVs (group III).