Complement Titres of Naturally and Artificially Raised Piglets: I. In piglets of different birth weights.

Titrations of haemolytic complement, C(1), activity have been carried out on serial weekly bleedings from four litters of piglets, a total of 39 animals. One of these litters was raised naturally on the sow, the other three litters were removed by hysterectomy and fed artificially without colostrum supplement. At one day of age the nursing piglets had considerably higher C(1) titres than the colostrum-deprived animals, owing presumably to their ingestion of maternal complement components from the colostrum. The naturally-raised piglets grew more rapidly and continued to have higher C titres during the first three weeks. After that time, although the artificially-raised piglets were still gaining weight more slowly, their C(1) titres began to compare favourably with those of the naturally-raised animals. Considerable variation was noted in the complement activity of sera of littermates. Deaths occurred among animals with high or with low C(1) titres.