As a general rule of thumb, a calf should receive 5 to 6 percent of its body weight as colostrum within the first 6 hours of life. That same amount should be fed again when the calf is about 12 hours old. Colostrum weighs approximately 8 pounds per gallon. For an 80-pound calf, this equates to approximately 2 quarts (4 pounds) of colostrum per feeding.