Association of production factors with milk IgA and IgM concentrations in normal lactating cows

Concentrations of IgA and IgM in milk from normal lactating cows were measured to determine whether they were affected by lactation number, lactation stage, daily milk production, milk composition and somatic cell score (SCS). A total of 284 Chinese Holstein cows showing no signs of mastitis were selected from more than 1600 cows from one farm. Concentrations of IgA and IgM in normal milk were determined by ELISA. Results revealed that average milk IgA and IgM concentrations were 235 +/- 11 and 32 +/- 3 mu g/ml, respectively. IgA and IgM concentrations in milk were found to have an association with lactation number, stage of lactation, daily milk production and SCS. Both SCS and daily milk production were found to be strong significant (P<0.01) direct factors correlating to IgA concentration. Stage of lactation and SCS were found to be strong significant (P<0.01) direct factors correlating to IgM concentration.