The aim of this study is to assess the effects of parity number on sow reproductive performance and the chemical and immunological composition of colostrum and immunoglobin concentrations in the sera of the sows. Colostrum samples were collected at 0, 6 and 24 h after the births of the first piglets from 56 sows with different numbers of parturitions (ranging 1-6). The piglets born alive to primiparous sows had lower birth weights (p < 0.05) than piglets from second and fourth parturition sows. The colostrum composition was influenced (p < 0.05) by parity number: primiparous sows had higher concentrations of dry matter, fat, lactose and non-fat-solids. No parity-dependent differences were found concerning total protein amount. Colostrum composition was drastically affected (p < 0.001) by sampling time-the highest concentrations of dry matter and protein and lowest concentrations of fat and lactose were found immediately after parturition (0 h). The study revealed no effect of parity (p ≥ 0.05) on the concentrations of immunoglobulins in colostrum. The immunoglobulin with the highest level in sow serum at day 110 of gestation was IgG, while IgA showed the lowest values and greater variability with respect to parity from an immunological point of view. Regarding the relationship between serum Ig levels at the end of gestation and colostrum Ig, serum IgG showed a strong correlation with colostrum IgG and IgM, while colostrum IgG was strongly related with colostrum IgM, but not with IgA. IgA did not correlate with any other immunoglobulin. The different behaviors of the immunoglobins in colostrum were probably due to IgG coming almost exclusively from the sows' sera, whereas IgA is mainly synthetized by the mammary gland.
Keywords: birth weight; colostrum; immunoglobulin; piglets; sows.