Piglets are born with very low energy reserves and devoid of immunoglobulins. Colostrum provides newborn piglets with energy for thermoregulation and body growth, passive immunity for protection against pathogens, and growth factors that stimulate the growth and maturation of tissues and organs, especially the gastrointestinal tract. Colostrum also provides cells and many bioactive components, e.g., hormones, cytokines, oligosaccharides, microRNAs, some of whose roles have not yet been determined or studied. The amount of colostrum ingested by newborn piglets is critical to their survival, growth and health. Colostrum yield and composition are highly variable among sows, but the factors that influence colostrogenesis are not fully understood. Strategies to increase colostrum yield are rare, although it appears that sow nutrition at the end of gestation may influence it. On the other hand, many strategies to improve colostrum composition are promising. ln particular, various ingredients with likely immunomodulatory effects (such as fish oil, prebiotics, and probiotics} increased immunoglobulin G or A concentrations in sow colostrum when administered during the last weeks of gestation. The passive immunity of piglets was then increased. Beneficial effects on the gut microbiota and immune system of piglets have also been reported, but need to be investigated further.