A calf's immune system is naïve at birth; she requires high-quality colostrum within the first few hours of life to achieve successful passive transfer of immunity through absorption of IgG across the intestinal wall and into circulation. LAND O LAKES Bovine IgG Colostrum Replacer is specially formulated to replace or supplement maternal colostrum as an aid in the treatment of failure of passive transfer. LAND O LAKES Bovine IgG Colostrum Replacer provides a newborn calf with important antibodies, including immunoglobulin G (IgG), to help develop her immune system.