SERUM IMMUNOGLOBULIN CONCENTRATIONS IN YOUNG DAIRY CALVES AND THEIR RELATIONSHIPS WITH WEIGHT-GAIN, ONSET OF PUBERTY AND PELVIC AREA AT 15 MONTHS OF AGE

Serum immunoglobulin (Ig) concentrations in 100 young dairy calves fro m five herds were determined to establish whether they were related to subsequent weight gain, age at puberty and pelvic area at 15 months o f age. Blood samples were collected from each calf at 6-48 h after bir th and at 2 weeks of age for Ig concentrations, and monthly from 210 d ays of age onward for progesterone assay to indicate age at puberty. P elvic area measurements were carried out at 15 months of age. Weight g ains were expressed as percentage weight gain from birth to the age be ing considered. Mean serum Ig concentrations at 6-48 h of age varied b etween herds and decreased (P < 0.01) by 2 weeks in all herds, with on e exception. The mean Ig concentrations in pooled data from the two Je rsey herds were different (P < 0.001) at 6-48 h and 2 weeks of age fro m those in the two Friesian herds, but not between herds within these breeds. The Jersey breed had the highest serum Ig concentrations, whil e the Friesian breed had the lowest. Significant positive correlations were found between Ig concentrations at 6-48 h after birth and at 2 w eeks of age in the Jersey breed (P < 0.05) and in the Illawarra herd ( P < 0.01). Although there were positive correlations (P < 0.05) betwee n serum Ig concentrations at 6-48 h and pelvic area at 15 months of ag e in one Jersey herd and between Ig concentrations (at 2 weeks of age) and pelvic area at 15 months in the Illawarra herd, there were no oth er correlations found between serum Ig concentrations at these ages an d subsequent weight gain, age at puberty and pelvic area at 15 months. In conclusion, serum Ig concentrations during the first 2 weeks of ca lves' lives were generally not related to parameters of calf growth an d reproduction.