Comparisons of packed cell volumes (PCVs) from so-called chicken anemia agent (CAA; a virus)-free broilers to PCVs from CAA-free specific-pathogen-free leghorns.

Packed cell volumes (PCVs) from 3-, 7-, 14-, 21-, 28-, and 35-day-old clinically healthy chicken anemia agent (CAA)-free and specific-pathogen-free (SPF) leghorn chicks were compared with PCVs from age-matched clinically healthy CAA-free broiler chicks. The PCVs of the SPF chicks regressed significantly (F = 20.6, df = 2/3, P < 0.025) on age in a linear fashion. The PCVs of the broiler chicks regressed significantly (F = 9.56, df = 2/3, P < 0.05) on age in a cubic parabola. The mean PCVs of the broiler chicks were significantly (P < 0.05) higher than PCVs of SPF chicks at every tested time interval. Results indicate that PCV values are higher in broiler chicks than in SPF leghorn chicks, and that PCVs increase as chicks age. Clinicians, diagnosticians, and investigators who intend to work with chicken blood must be aware of these differences.