Colostrum cellularity was studied in 53 Holstein cows using 171 samples, collected before the first and second postpartum milking. Direct microscopic counts and cytocentrifugation were used in the quantitative and qualitative cytological analyses. The total number of leukocytes obtained by means of direct microscopic count was equal to 0.878 x 10(6) and 1,260 x 10(6) , before the first and second milking, respectively. The median of phagocyte counts before the first and second milking were, respectively,0.657 and 0.828 x 10(6) mononuclear leukocytes, and 0.178 and 0.392 x 10(6) polymorphonuclear leukocytes (P<0.0001). The median of leukocyte counts, before the first and second milking were, respectively, 0.640 x 10(6) and 0.772 monocytes/epithelial cells; 0.136 x 10(6) and 0.098 lymphocytes; 0.045 x 10(6) and 0.203 x 10(6) neutrophils. It was concluded that bovine colostrum of the second milking showed an increase in the number of somatic cells and polymorphonuclear leukocytes and polymorphonuclear leukocytes/mL. This variation may be either related to the importance of colostrum to neonates, or to physiological and defense changes that occur in the mammary gland during immediate after postpartum.
dairy cow; colostrum; cytology; phagocytes
