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SUMMARY The concentrations of immunoglobulin (Ig)G, IgM, IgA, and albumin in the lacteal secretion of 80 sows were measured not more than 14 times during lactation to determine whether the age of the sow, the anatomic location of the mammae, or the farrowing barn housing of the sow influenced Ig concentrations. The combined data indicated that there were lactation stage-dependent changes in the total Ig concentration, as well as changes in the relative importance of the 3 classes of Ig studied. Mean values of any one time point showed enormous variation in absolute values, with coefficients of variation ranging up to 70%. The largest variations were observed between colostral samples obtained on the first day. The IgM showed the least variation on day 1. Such variations hindered attempts to statistically identify their source. Normalization of Ig concentrations in relation to albumin concentrations decreased some of the apparent variation. Normalized data accentuated the changeover from colostrum to milk which occurred after the first 3 days. There was also a 3-fold increase in IgA concentrations which occurred during the last 4 weeks of lactation. Data showed that older sows tended to have higher concentrations of all Ig. Lactation number-dependent increases in IgM and IgG were restricted to colostrum in lactation numbers higher than 4. Immunoglobulin A increased in a similar pattern and, in addition, increased in mature milk in sows with more than 2 lactations. The enormous variations observed seemed to be individual animal variations. This allowed only trends, rather than statistically significant differences, to be recognized. Several such trends were apparent. First, variations among individual mammae were not greater than overall variations, supporting the view that variations were individual animal variations. Secondly, caudally located glands showed a tendency to have higher Ig concentrations and lower albumin concentrations than other mammae. Thirdly, IgG, IgM, and albumin concentrations seemed to be highest in sows of 1 to 2 lactations, whereas IgA concentrations were higher in older sows. Finally, sows housed in different farrowing barns had different relative concentrations of IgG:IgA:IgM in colostrum, which was maintained into early lactation. It was concluded that variation in the amount of lacteal Ig in sows, other than those which are associated with differences in the stage of lactation, cannot be ascribed to a single physiologic factor. Individual animal variation seems to have the largest influence.
Klobasa et al. (Sun,) studied this question.