Changes in colostral and serum IgG content in swine in relation to time.

Changes in the IgG concentration in the colostrum from separate tests of 6 sows and those in the sera of their 38 piglets were investigated. Colostrum was frequently sampled from parturition to 120 hours and blood was taken from the piglets from birth to 10 weeks of age. The IgG content of the colostrum decreased to 3.2% of the original concentration at the 5th day of lactation. The meaningful variation of the IgG concentration of the colostra obtained from different teats increased rapidly from 12 hours postpartum. between-sow variation was high and no correlation of the IgG concentration of the colostrum with the average serum level of the corresponding litter could be confirmed. Of the newborn pigs, 33% possessed IgG before ingesting colostrum, the observed concentration was 0.09 +/- 0.02 mg/ml (mean +/- SEM). At 0.5 and 1.5 hours after access to colostrum, this value was 2.30 +/- 1.38 and 1.89 +/- 0.60 mg/ml respectively. The highest IgG concentration (39.45 +/- 1.46) was observed at 24 hours after birth. Following that, a stepwise drop occurred in the IgG level and the lowest value was observed in the 4th week of age (8.92 +/- 0.59 mg/ml). Subsequently, there was a continuous rise until 10 weeks of age when the concentration reached the value characteristic of adults. The calculated half-life of the IgG in the sera showed a significant between-litter variation. The average half-life of the serum IgG of pigs was 9.73 days.