Abstract: Through remaking the power motor, screw extruder and discharge hole of the cooking extruder, the gelatinizing machine (extruder) was developed. By the gelatinizing machine, starea (gelatinized starch with urea) were produced which could reach the quality standards and safety requirements. The feeding effects of starea on dairy cows were significant and could substitute for parts of soybean meal. The better levels of starea in mixed concentrate for early and middle lactation phases were 5% and 8% respectively.