The slaughtering of pregnant animals is, in most cases, an unplanned event. The frequency depends on farming techniques. In most cases, the condition of gestation is unknown; especially where animals are produced naturally; in the case of cattle moving freely around, grass fed, heifers and steers together. No cows are killed with the main purpose of harvesting the fetal blood. The blood is collected as a by-product from cattle slaughter operations for the bovine meat. The pregnancy condition is unknown when an animal enters the slaughtering line. The percentage of pregnant cows going to slaughter is very low and decreasing year by year as cattle farming techniques constantly improve.