Erythrocyte and leukocyte parameters in newborn lambs

SUMMARY Erythrocyte and leukocyte values were estimated in samples of blood from 32 lambs varying in age from 142 to 180 days post conception. Total erythrocyte count, packed cell volume and haemoglobin levels all decreased during the period 142 to 160 days, but rose afterwards. The mean corpuscular volume and mean corpuscular haemoglobin levels decreased in a similar manner but did not increase subsequently. Volume distribution curves exhibited a progressive fall in the standard deviation, accompanied by an increase in the coefficient of variation and degree of skewness. A small but significant number of reticulocytes was present at 150 to 160 days post conception. The total nucleated cell population showed no significant variation during the period under review. The lymphocyte/neutrophil ratio rose significantly from 160 to 180 days post conception. A transient increase in the numbers of neutrophil precursors at 150 to 160 days was not accompanied by a left shift in segmented cells.