Effects Of Super-dose Of Phytase In Diet On Production Performance,Tibial Development,and Nutrient Utilization Of Meat Ducks

This paper,taking Cherry Valley Ducks as object,was aimed to study the effects of super-dose of phytase in dietary on meat ducks,and then attempt to provide a solution for it.Three experiments were conducted to investigate respectively the effects of high temperature resistance of phytase,optimal dosage for meat ducks,and interactions between phytase and alkaline on production performance,tibial development and nutrient utilization of meat ducks.Exp.1 Study on the Resistance of Phytase Activity from Different Sources via High TemperatureFour kinds of dietary phytase,A,B,C and D,were selected on the market,which were treated by 85 degree centigrade water-bath for 3min/4min,and treated by granulated,respectively.The results showed that: activity retention rate of phytase C was the highest via high water-bath temperature and granulation,followed by phytase A,phytase B and phytase D in sequence.Exp.2 Effects of Super-dose of Phytase in Low Phosphorus Diet on Production Performance and Tibia Development of Meat DucksA single factor test was used to select 560 healthy Cherry Valley Ducks,which were randomly divided into 7 groups with 5 duplicates and 16 ducks each.The test included 2 phases(1-14 and 15-35 days old).Positive control group was feed in normal diet.Negative control group was feed in low phosphorus diet.Phytase groups were feed in retention of phytase with 500、1000、2000、3000、4000U/kg,respectively,on the bases of negative control diet.The results showed that: Adding super-dose of phytase improved the production performance of meat ducks.The weight of tibia,ash,calcium and phosphorus content in tibia were positively correlated with the dosage of phytase,on the contrary,iron levels were negatively correlated.The optimal retention range of phytase in meat duck diet was 1599.12-1676.51U/kg by regression analysis and broken quadratic fitting.Exp.3 Effects of Adding Phytase and Alkaline in Diet on Production Performance,Tibial Development,Nutrient Utilization and Serum Index of Meat Ducks.Using 2*2+2 test design,576 1-day-old ducks were randomly divided into 6groups with 6 duplicates and 16 ducks each.Group Ⅰ was feed in normal diet.Group Ⅱwere feed Group Ⅰ diet with crude protein decreased of 1%.Group III was feed withGroup Ⅰ + retained phytase 1600 U / kg diet.Group IV was feed Group Ⅱ +retained phytase 1600 U/kg diet;Group V was feed with Group Ⅱ +alkaline 200g/t diet;GroupⅥ was feed with Group Ⅱ+ retained phytase 1600 U/kg+ alkaline 200g/t diet.The test included 2 phases(1-14 and 15-35 days old).The result showed that: phytase increased production performance,tibia index and nutrient utilization,also influenced serum indicators for meat ducks;alkaline improved feed conversion,nutrient utilization;interactions were presented in tibia index,nutrient utilization and serum indicators between phytase and alkaline.The results of three experiments above showed that the effect of extracting after 4minutes in water-bath of 85 degree centigrade on the retention of phytase activity has the best correlation with granulation treatment.The optimum dose of phytase in diet for meat ducks is 1600U/ kg.Phytase can significantly improve ADG,ADFI for meat ducks and tibia length,weight,ash content,and also increase the utilization rate of crude protein,amino acid and minerals in diet.Alkaline can significantly increase ADG and ADFI in early stage of meat ducks,and improve the utilization of crude protein,amino acids and minerals in diet.Phytase and alkaline significantly interact on the contents of tibia calcium,phosphorus,copper and iron at the age of 14 days and the utilization of amino acids and minerals in diet at the age of 35 days for meat dusks.