Colostral volume and immunoglobulin G and M determinations in mares.

Colostral volume and IgG and IgM concentrations were determined in 6 multiparous mares at foaling and them every 2 hours from 16 to 20 hours after parturition. Serum IgG and IgM concentrations at foaling also were determined in each mare. The rate of mammary secretion was 292 +/- 26 ml/h (range, 202 to 389 ml/h), and the colostral volume was 5.1 +/- 0.5 L (range, 3.2 to 7.0 L). The colostral IgG and IgM contents were 440 +/- 106 g (range, 199 to 855 g) and 3.1 +/- 0.9 g (range, 0.7 g to 7.1 g), respectively. There was no significant correlation between serum and initial colostral IgG and IgM concentration or between serum and total colostral IgG or IgM values. The colostral IgG and IgM concentrations at foaling correlated well with the total colostral IgG and IgM contents, respectively. The initial 250 ml of colostrum contained 10 +/- 1.4% (range, 6.0 to 13.9%) and 6 +/- 1.0% (range, 2.4 to 8.5%) of the total IgG and IgM contents, respectively, and the initial 500 ml of colostrum contained 20 +/- 2.7% (range 12.0 to 27.1%) and 14 +/- 1.2% (8.2 to 17%) of the total colostral IgG and IgM contents, respectively.