Individual variation in immunoglobulin contents of first colostrum may be responsible for differences in susceptibility of calves to infections. The present study was undertaken to analyze effect of various non genetic factors on the concentration of immunoglobulin G in the colostrum of dams before start of the first milking. Colostrum (before first milking) of 40 newly parturated Murrah buffaloes maintained at Livestock Production Management (LPM) Section of IVRI, Izatnagar, was digested with rennet and then analyzed by indirect ELISA. Records pertaining to calving including parity of dam (1 through 8), season of calving (rainy, autumn and winters), time of calving (day and night) and volume of colostrum (at first milking) were collected and analyzed by least square analysis and regression analysis. Levels of IgG in buffalo colostrum (before first milking) estimated by indirect ELISA ranged from 11.22 to 185.1 mg/ml and mean IgG concentration in colostrum was 51.71 ± 5.99 mg/ml. The effect of parity of dam and colostrum volume (first milking) on colostral IgG concentrations was found to be significant at p<0.01 and p<0.05 levels respectively, whereas, effect of calving season and time of birth were found to be non significant.