The total number of samples tested was 440, including 223 colostrum and 217 mature milk samples. The frequency of detectability was significantly different between colostrum and mature milk for 6 cytokines: IL-12, P≤0.001; IL-4, P<0.001; IL-1ra, P<0.001; IFN-γ, P=0.01; IL-10, P=0.01; IL-2, P=0.02. Statistical significance was calculated using the Chi square test. * indicates P values <0.05.