Antioxidant defence of colostrum and milk in consecutive lactations in sows

The activity of antioxidative enzymes and the concentration of vitamin A increased with time postpartum. The concentration of vitamin C was the highest between the 18th and 36th h postpartum.Dynamic changes in the values of antioxidant parameters measured during the study showed that sows milk provides the highest concentration of antioxidants in the 2nd and 3rd and 4th and 5th lactation giving the best defence against reactive oxygen species to newborns and mammary glands.Pregnancy is a period of constant oxidative stress for the dam [1]. Moreover, perinatal stress and the related changes in oxygen partial pressure, may result in the exposition of the newborn to an excess of reactive oxygen species (ROS) during pregnancy, parturition, and postpartum. This happens mainly due to parturition-related alterations in steroid and prostaglandin metabolism in the dam but also due to the change from interauterine to extrauterine environment and the beginning of lung breathing in the newborn [2,3]. An uncontrolled imbalance between the production and neutralization of ROS may cause oxidative stress. It may lead to serious consequences not only for the cell membrane, which can change its permeability, but also for the proper course of metabolic processes, which can be altered due to peroxidative damage of enzymatic proteins and the presence of the toxic products of the peroxidative damage to macromolecules [4]. Antioxidant systems located in all cells and biological fluids protect biologically important proteins and other macromolecules from the peroxidative damage caused by ROS [5].Colostrogenesis starts before parturition and results in production of a thick yellow fluid named colostrum which then accumulates in mammary glands and is secreted by the sows for 2-3 days after parturition [6]. After cessation of the colostrum secretion, it is referred to as mature milk, which differs from colostrum by the concentration of proteins which is due to the decrease in the content of i