Certain hormones may be used to make young animals gain weight faster. This practice may reduce the waiting time and the amount of feed eaten by an animal before slaughter in meat industries. Zeranol, trenbolone acetate, and melengesterol acetate are synthetic growth promoters (man-made, hormone-like chemicals that may make animals grow faster). Currently, federal regulations allow these hormones to be used for growth of cattle and sheep, but not for poultry (chickens, turkeys, ducks, etc.) or hogs (pigs). The above hormones are not as useful in increasing weight gain in poultry or hogs.