Colostrum management for the newborn calf is arguably one of the most important events in a calf's life. Handling this event properly will impact the growth, performance and health of the calf for it's entire life. Ensuring that the calf nurses an appropriate amount of colostrum as soon after birth is essential. A good rule of thumb is to ensure that the calf receives colostrum within the first 6 hours of life is best, but at a maximum by 24 hours of age. Past 24 hours, the benefit to colostrum is lost. The Iowa Beef Center has a good handout on colostrum management that you can read here.