Enumeration of NK cells from birth to adulthood. (A) The proportion of NKp46+ cells among PBMC from cattle at different ages was determined by flow cytometry. (B) Total number of NKp46+ cells per litre of blood. Individual values and medians are presented. Statistical analysis was carried out with a nonparametric Mann–Whitney test (p value is indicated above the scatter plot). (C) The proportion of NKp46+ cells among PBMC from five animals (ID # 1 to 5) within the first two weeks of life was determined by flow cytometry.