Method for comprehensively utilizing soft bones of livestock and poultry

The invention discloses a method for comprehensively utilizing soft bones of livestock and poultry. According to the method, the soft bones of various livestock and poultry are crushed, then are added with a 10% sodium hydroxide solution which is twice the weight of the crushed bones, and are heated in water bath to 40-60 DEG C, soaked for 10-12 hours and filtered; the filtrate is regulated with sulfuric acid until the pH value is 3-4and stands for one hour and then is filtered; filter residues are washed repeatedly with clean water till neutrality, and are dried and crushed below 60 DEG C to obtain bone protein; the filtrate is regulated to neutrality by using sodium hydroxide, is added with proteinase accounting for 2wt% of the crushed bone, is heated in water bath to 60 DEG C, hydrolyzes for 10 hours by keeping the temperature unchanged and is filtered, the filtrate is vacuum-evaporated under the conditions of 0.5 MPa and 60 DEG C, the dry substances obtained after evaporation are washed for 2-4 times with 90% ethanol and filtered to obtain chondroitin sulfate. The process of alkali-solution and acid-isolation is used in the method so that chondroitin in soft bones is fully soaked, and the yield and quality of chondroitin sulfate are greatly improved.