Leukopenia in neonatal Japanese quail

Japanese quail were sacrificed at one or two days after hatching. several hematological parameters were measured. A leukopenia occurred in the two-day-old quail. Concomitantly the circulating numbers of lymphocytes were reduced in the older quail. It appears that this functional leukopenia is attributable to reduced numbers of lymphocytes and may represent an heretofore undefined physiological adaptive mechanism which occurs during the early neonatal period.