The aim of the study was a search for new polymorphisms in the genes related to lactogenesis, including lactose synthesis in colostrum and milk, and determine their relationship with the content of colostrum and milk components and body weight of the piglets. Colostrum and milk were sampled during the second lactation on d 1, 7, 14 and 21 from 112 sows of Polish Large White (PLW) and Polish Landrace (PL). The piglets’ rearing performance was determined based on the number and body weight at 1, 7, 14 and 21 d of age. In the study six polymorphisms located in different genes were analysed. Among the six polymorphisms under analysis, those identified in the