Maternal-neonatal immunoregulation: suppression of de novo synthesis of IgG and IgA, but not IgM, in neonatal pigs by bovine colostrum, is lost upon storage

Fifty-four neonatal pigs were allotted to 4 groups and reared in an electrically controlled automatic feeding device (autosow). Each group was reared on a different pool of bovine colostrum: fresh, stored 1 month, stored 6 months, and stored 8 years. Bovine and porcine immunoglobulins in the sera of these pigs, and in a group of conventionally reared pigs, were measured periodically during the first 42 days after birth. The maximal concentration of absorbed bovine immunoglobulin was reached between 12 and 18 hours and equaled or exceeded the amount of porcine immunoglobulin absorbed by the conventionally reared pigs. Large differences in the concentrations of the bovine immunoglobulin isotypes among the various pools of colostrum were positively correlated with concentration of these isotypes in the sera of the neonatal pigs fed these pools. Relative to their concentrations in colostrum, approximately 41% of the IgG1, 55% of the IgG2, 29% of the IgM, and 67% of the IgA was absorbed. The IgA was absorbed the best and IgM was least absorbed. Significant trends or differences in absorption were not observed among groups. Neonatal pigs given fresh colostrum, which had a higher fat content, had significantly more weight gain (P < 0.05). This occurred, despite the fact that the fresh colostrum had the lowest concentration of bovine immunoglobulin. Serum half-lives for bovine IgG1 and IgG2 were significantly less than for porcine IgG (P < 0.05), whereas the half-lives for bovine and porcine IgM and IgA were similar. De novo-synthesized immunoglobulins were detectable in serum after 6 days; IgM concentrations reached a maximum at 15 days in neonatal pigs given stored, but not fresh, colostrum. The IgG and IgA concentrations steadily increased in all groups and were highest on day 42, when the study was terminated. Neonatal pigs ingesting fresh colostrum had significantly lower concentrations of de novo-synthesized IgG and IgA than pigs fed stored colostrum (P < 0.05). Concentrations in these pigs were also lower than those in conventionally reared pigs. This occurred, despite the lower immunoglobulin concentration in fresh colostrum, and correspondingly, the lower amount of bovine immunoglobulin in pigs that received this colostrum and absorbed it into their serum. In most instances, the amounts of immunoglobulin of any isotype absorbed from stored colostrum and the amount of de novo-synthesized immunoglobulin present 6 weeks later, were inversely correlated. Data indicated that a storage-labile, nonimmunoglobulin factor, in bovine colostrum is able to suppress de novo IgG and IgA synthesis by neonatal pigs.