Evaluation of Standardized Ileal Digestibility of Amino Acids of Corns in Layer Chickens during Brooding Period and Establishment of Their Prediction Equations
This study was to evaluate the physicochemical characteristics of corns from different producing are-as and their apparent ileal digestibility(AID)and standardized ileal digestibility(SID)of amino acids in layer chickens during brooding period,and to build prediction equations of amino acid SID based on physical charac-teristics and chemical composition contents of corns.A total of 528 healthy Jinghong No.1 chicks of 31-day-old with similar body weight of(284±10)g were randomly divided into 11 groups with 6 replicates per group and 8 chickens per replicate.Chickens in C0 group were fed a nitrogen-free diet,and those in C1 to C10 groups were fed semi-homozygous experimental diets prepared with corns from different producing areas.Besides,0.50％titanium dioxide(TiO2)was added to both the nitrogen-free diet and experimental diets as exogenous indicator.The experiment lasted for 3 days.After the experiment,all chickens were stunned with carbon diox-ide(CO2)gas and then slaughtered.The chyme at the end of the ileum was collected to determine the contents of amino acids and TiO2 to calculate amino acid SID.The results showed as follows:1)under the air-dry ba-sis,on average,the 10 kinds of corns contained 19.29 MJ/kg(18.03 to 23.81 MJ/kg)gross energy(GE),86.95％(84.45％to 89.24％)dry matter(DM),7.96％(6.89％to 9.52％)crude protein(CP),3.43％(2.03％to 4.50％)ether extract(EE),1.26％(1.00％to 1.58％)crude ash(Ash),8.12％(7.50％to 9.52％)neutral detergent fiber(NDF),2.40％(1.86％to 3.66％)acid detergent fiber(ADF),0.26％(0.18％to 0.31％)total phosphorus(TP),0.05％(0.01％to 0.13％)calcium(Ca)and 65.93％(56.75％to 70.64％)total starch(TS),and the bulk density,1 000 grain volume and 1 000 grain weight of corns were 756.47 g/L(695.19 to 799.18 g/L),446.40 mL/1 000 grains(364.00 to 504.00 mL/1 000 grains)and 337.90 g/1 000 grains(250.15 to 381.55 g/1 000 grains),respectively.Some essential amino acid contents in corns were 0.16％(0.10％to 0.21％)for methionine,0.25％(0.22％to 0.32％)for lysine,0.31％(0.26％to 0.40％)for threonine and 0.06％(0.05％to 0.08％)for tryptophan,respectively.2)The amino acid SID of corns in layer chickens during brooding period was 92.35％for methionine,87.85％for lysine,82.86％for threonine and 83.98％for tryptophan,respectively.3)The determination coefficient(R2)of SID prediction equations for 17 amino acids of corns in layer chickens was ranged from 0.663 to 0.965,in which the serine SID prediction equation had the highest fitting degree(SID=79.130+0.541GE+7.144Ash-2.767NDF+49.646glycine,R2=0.965,P＜0.01),and the R2 of SID prediction equations of phenylalanine,valine and cystine was exceeded 0.90,indicating a good fit.In conclusion,this study confirms the large varia-tion in physical characteristics and chemical composition of corns from different producing areas,which is the main reason for the difference in AID and SID of amino acids of corns from different producing areas in layer chickens during brooding period.Among them,the GE and contents of CP,EE,ADF,NDF,TS and some a-mino acids in corns can be used as key predictors of amino acid SID.[Chinese Journal of Animal Nutrition,2024,36(9):5693-5708]
layer chickens during brooding periodcornphysicochemical characteristicsamino acid digesti-bilityprediction equation
万方数据
维普
