Calcium source feed is very cheap, but it cannot be used in excess, otherwise it will affect the balance of calcium and phosphorus, which will affect the digestion, absorption and metabolism of calcium and phosphorus. Pre-mixes of trace elements often use stone powder or shell powder as a diluent or carrier. When the usage amount is relatively large, the amount of calcium should be taken into consideration in the ingredients. 1. Shell powder: Shell powder is a kind of powder or granular product processed and crushed by various shellfish shells (clam shell, oyster shell, scallop shell, hag shell, snail shell, etc.), mostly gray, gray and gray. Brown powder. The main component is also calcium carbonate, calcium content should not be less than 33%, generally between 34% to 38%. Good quality shell powder with less impurities, high calcium content, white powder or flake, used for layer or breeder feed, the eggshell has high strength, less broken eggs, and calcium carbonate is also included in the 95 More than % is an acceptable source of calcium carbonate, especially for flakes. The particle size requirements of shellfish powder for different livestock and poultry require that pigs pass 25% through 50mm, layers should pass 70% through 10mm, and broilers should pass 60% through 60mm. China’s coastal areas are rich in resources and have many applications. Shell powder is often doped with impurities such as sand and dirt, and should be inspected during use. In addition, if the shellfish has not been depleted, and the storage is improper, the accumulation will be prone to mildew, rancidity, etc., which will significantly reduce the value of feed. It must be sterilized to prevent transmission of disease. Pay special attention when purchasing and applying. 2. Gypsum: Gypsum is calcium sulfate (CaSO4XH2O), usually calcium sulfate dihydrate (CaSO42H2O), a gray or white crystalline powder. There are natural gypsum crushed products, but also chemical industry products. If it is a by-product from the phosphoric acid industry, it is of poor quality because it contains high amounts of fluorine, arsenic, and aluminum, and should be treated when used. The calcium content of gypsum ranges from 20% to 23%, and sulfur content ranges from 16% to 18%. It not only provides calcium but also a good source of sulfur with high bioavailability. Gypsum has the effect of preventing chicken feathers and licking. The amount used in the feed is generally 1% to 2%. 3, eggshell powder: egg shells or egg hatchery abandoned plant shells, eggshells, egg membranes and protein residues after drying sterilization, crushed to get eggshell powder. No matter eggshells after egg processing or eggshells after hatching, there are shell membranes and some proteins, so in addition to containing about 34% calcium, it also contains 7% protein and 0.09% phosphorus. The eggshell is mainly composed of calcium carbonate, but due to the indefinite residue, the calcium content of the eggshell powder changes greatly, generally between 29% and 37%. Therefore, the product should indicate the content of calcium and crude protein, and the product is not indicated. The user should determine calcium and protein content. Eggshell powder is an ideal calcium source feed, and has a high utilization rate. It is used in the feed of laying hens and breeders. It also has the effect of increasing the rigidity of shells as well as shell powder. It should be noted that the dry temperature of the eggshell should exceed 82°C to ensure sterilization, prevent protein spoilage, and even spread the disease. Eastony Industries (NingBo) Co., LTD. , https://www.eastony.com