In the broiler feed, phytase increased from 0.5 to 8 FTU/g, and the weight gain and feed conversion rate of broilers gradually increased with the addition of phytase. Under low phosphorus levels, adding 0.5 FTU/g phytase can reach normal phosphorus levels. growth performance;In yellow feather broilers, the addition of 4 FTU/g phytase can also significantly reduce the feed ratio and improve weight gain to a certain extent; without reducing calcium hydrogen phosphate, 1 FTU/g phytase level can achieve the best results Feed ratio, 5 FTU/g phytase level can achieve the best feed intake and weight gain, indicating that the phosphorus in normal conventional diets may be in a relatively insufficient state.In meat duck diets, overdose supplementation of phytase can offset the negative effects of low phosphorus on growth performance and tibial bone mineralization, and achieve better growth performance; overdose supplementation of phytase in calcium-free diets (2-6 FTU/g) for better performance than normal phosphorus levels. Different diets and different stages can be phased without adding hydrogen calcium.In laying hen feed, adding phytase (1 FTU/g) to low-phosphorus diet in excess dose can increase digestive enzyme activity, improve laying performance, and improve egg quality (Hastelloy unit, yolk color, egg shape index).In the growing poultry feed, adding 2 U/g phytase in excess dose can release 0.04-0.06% more available phosphorus and save 1.0-1.8 kg of calcium hydrogen phosphate per ton. In pig feed, 0.5 U/g phytase can reduce 0.22% calcium and 0.19% phosphorus in the diet (9.8 kg/T MDCP). Nutrient digestibility, growth performance and intestinal development are the best at U/g; in nursery pig feed, adding 2 U/g phytase has the best weight gain and feed conversion rate of piglets, total phosphorus and phytate phosphorus ileal appearance The digestibility gradually increased with the level of phytase, and the feed ratio decreased gradually. The effect of phytase in promoting pig feed intake is not obvious, but it has significant effect in increasing daily weight gain, reducing feed ratio, increasing calcium and phosphorus digestibility, and reducing phosphorus emission. In the large pig feed, adding 2 U/g phytase in excess dose can release 0.02-0.06% more available phosphorus and save 0.4-2.5kg of calcium hydrogen phosphate per ton. At present, the level of phytase addition in feed enterprises is basically 2-6 U/g feed, and the addition of 4-12 times the standard dose, and the addition of excessive doses has become the norm.