Abstract: 【Objective】 This experiment was conducted to investigate the effects of phytase supplementation in low phosphorus diet on growth performance,plasma biochemical parameters,carcass traits,the contents of total nitrogen and total phosphorus in the feces of geese from 28 to 70 days of age.【Method】 A total of 200 28-day-old geese were randomly allotted to 5 groups with 5 replicates per group and 8 goslings per replicate.Geese in the positive control group (PC group) were fed a routine diet containing 0.7% total phosphorus (available phosphorus level were 0.35%),geese in the negative control group (NC group) were fed a low phosphorus diet containing 0.5% total phosphorus (available phosphorus level were 0.15%),and others in experimental groups were fed low phosphorus diets supplemented with 1 000 (NC1000 group),2 000 (NC2000 group) and 4 000 IU/kg (NC4000 group) phytase,respectively.The experiment lasted for 42 days.The feed intake,initial body weight,and final body weight of each replicate were recorded to calculate the average daily gain,average daily feed intake,and feed/gain.At the age of 70 days,two geese were selected from each replicate for blood collection from the wing vein to determine plasma biochemical parameter.One goose was selected from each replicate according to the average body weight of corresponding replicate and were slaughtered for carcass trait measurement.Two geese were selected from each replicate according to the average body weight for droppings collection,and determination of total nitrogen and total phosphorus.【Result】 ① The final body weight,average daily gain and average daily feed intake of geese in PC,NC1000,NC2000 and NC4000 groups were significantly higher than those in NC group (P＜0.05),there were no differences in feed/gain among the groups (P＞0.05).② The plasma phosphorus content of geese in PC,NC1000,NC2000 and NC4000 groups were significantly higher than those in NC group (P＜0.05),the plasma alkaline phosphatase activity of geese in NC2000 and NC4000 groups were significantly lower than those in NC and NC1000 groups (P＜0.05),phytase supplementation in low phosphorus diet had no significant effect on plasma total protein,albumin,globulin,glucose,triglyceride,cholesterol and calcium concentrations and alanine amino transferase,aspartate amino transferase,lactate dehydrogenase activities of geese (P＞0.05).③ The dressed percentage and half eviscerated ratio of geese in the PC,NC1000,NC2000 and NC4000 groups were significantly higher than those in NC group (P＜0.05),phytase supplementation in low phosphorus diet had no significant effect on eviscerated ratio,breast muscle ratio,leg muscle ratio,lean meat ratio,abdominal fat ratio,skin fat ratio and intestinal weight and length of geese (P＞0.05).④ Phytase supplementation in low phosphorus diet had no significant effect on the total nitrogen content in the feces of geese (P＞0.05),the total phosphorus content in the feces in NC,NC1000,NC2000 and NC4000 groups were significantly lower than those in PC group (P＜0.05).【Conclusion】 The phytase supplementation in low phosphorus diet could improve the growth performance and carcass trait of geese from 28 to 70 days of age,and decrease emission of phosphorus.Under this experiment condition,the suitable addition of phytase was 1 000 IU/kg in low phosphorus diet that total phosphorus was 0.5%.

Key words: phytase; goose; growth performance; plasma biochemical parameter; carcass trait