| This study was conducted to investigate the effects of lipase on growth mechanism of broilers by two experiments.Firstly,different concentrations of lipase were added under different dietary conditions of two oils(soybean oil and duck oil).The total fecal urine method was used and which was studied on the utilization rate of conventional nutrients,amino acids and energy in broiler chickens at different fat diets,fat levels and lipase levels,and the appropriate amount of lipase was determined.Secondly,under the optimal dietary conditions of lipase,the effects of lipase supplementation on the performance,meat production and intestinal microbes of broilers were studied by feeding comparison test.Effects of lipase on nutrient and energy utilization in broilers:In order to investigate the effects of lipase on nutrient and energy utilization in broiler chickens,experiment using five hundred and twelve 14-d-old male Arbor Acres(AA)broilers that were randomly allocated to 32 treatments with 8 replicates(2 broilers/replicates)in a complete randomized design.Divided into two fat diets(soybean oil and duck oil),each fat diet is divided into 4 oil levels(0%,2%,4%,6%),and each fat level is divided into 4 lipase levels(0 mg/kg,100 mg/kg,200 mg/kg and 400 mg/kg).In addition,16 chickens(1 treatment × 8 replicates × 2)were selected and used as endogenous metabolic treatment to analyzed the true digestibility of broilers.The total fecal urine method was used and the adaptation period was 14 to 21 days and the trail period was 22 to 35 days.The test chickens were caged,free to drink and eat.The result of this experiment indicated that in duck oil diets,the addition of different concentrations of lipase can linearly increase(P<0.05)the AD of DM and OM,linearly increase(P<0.05)the TD of OM,and DM utilization has an increasing tendency(0.05<P<0.1)in broilers compared with those of control treatment.Broilers had the highest DM and OM utilization when 400 mg/kg lipase was added.In soybean oil diets,supplementation of different concentration gradient of lipase can linearly increase(P<0.05)the AD of DM,OM,CP,GE,EE and AME,and linearly and quadratically increase(P<0.05)the TD of OM,GE and AME.The best DM,OM,CP and GE nutrient availability and metabolizable energy values were obtained by adding 400 mg/kg lipase than others.Different fat levels in the diet can linearly and quadratically reduce(P<0.001)the AD of DM,OM and EE in broilers,increase(P<0.05)AME compared with those of control treatment.Regardless of the level of dietary oil,the addition of different concentrations of lipase in the diet can linearly and quadratically increase(P<0.05)the AD of DM,OM,CP and GE and AME value in broilers(P<0.05)compared with the control group,and when the amount of lipase added reached 400 mg/kg,the AD of DM,OM and CP nutrients in broilers could be significantly increased(P<0.05).Adding 200 and 400 mg/kg could significantly improve(P<0.05)the AD of GE of broilers and AME values.Effects of lipase on the amino acid utilization rate of broiler diet:using the above method of digestion and metabolism test,the results of the study on the full amino acid utilization rate of broiler diets indicated that:supplementation of different concentration gradient of lipase can linearly increase(P<0.05)the AD of Lys,Try,His,Leu,Phe,Thr,Gly,Cys,Ser,Ala,Pro,TEAA and TNEAA of broilers in duck oil diets,quadratically increase(P<0.05)the AD of Try,His,Leu,Phe,Ser,Pro,TEAA and TNEAA compared with the control group.Dietary supplementation of 400 mg/kg lipase significantly increased(P<0.05)the AD of Try,Leu,Thr,Cys,Ser,and Pro in broilers.In soybean oil diets,supplementation of different concentration gradient of lipase can linearly increase(P<0.05)the AD of Try,Arg,His,Ile,Phe,Thr,Tyr,Ser,TEAA and TNEAA,quadratically increase(P<0.05)the AD of Try,His,Ile,Phe,Thr,Tyr,Ser of broilers.Dietary supplementation of 400 mg/kg lipase significantly increased(P<0.05)the AD of Try,His,Ile,Phe,Thr,Tyr,Ser of broilers compared with those of control diet.Increased lipid levels in diets reduced(P<0.001)theAD of Try,Arg,His,Ile,Phe,Thr,Val,Gly,Tyr,Asp,Ser,Glu,Ala,Pro,TEAA and TNEAA in broilers.Regardless of the level of dietary oil,adding different concentrations of lipase in the diet can improve(P<0.05)the AD of Try,Arg,His,Leu,Phe,Thr,Gly,Cys,Tyr,Ser,Glu,Pro,TEAA and TNEAA compared with the control group,and linearly and quadratically increase(P<0.05)the AD of Lys,Ile,Val,Gly,Cys,Ser,and Pro in broilers.Dietary supplementation of 400 mg/kg lipase significantly increased(P<0.05)the AD of Lys,Tyr,Arg,His,Leu,Phe,Thr,Gly,Cys,Tyr,Ser,and Pro in broilers.Supplementation of different concentration gradient of lipase can linearly increase(P<0.05)the TD of Lys,Try,His,Leu,Phe,Thr,Val,Gly,Cys,Ser,Ala,Pro,TEAA and TNEAA of broilers in duck oil diets,quadratically increase(P<0.05)the TD of Try,His,Leu,Phe,Ser,Pro,TEAA and TNEAA compared with the control group.Dietary supplementation of 400 mg/kg lipase significantly increased(P<0.05)the TD of Lys,Tyr,Leu,Thr,Cys,Ser,and Pro in broilers.In soybean oil diets,supplementation of different concentration gradient of lipase can linearly increase(P<0.05)the TD of Try,Arg,His,Ile,Phe,Thr,Tyr,Ser,Glu,TEAA and TNEAA,quadratically increase(P<0.05)the TD of Try,His,Phe,Ser,TEAA and TNEAA of broilers.Dietary supplementation of 400 mg/kg lipase significantly increased(P<0.05)the TD of Try,His,Phe,Tyr,Ser of broilers compared with those of control diet.Different lipid levels in the diet reduced(P<0.001)the TD of Try,His,Ile,Phe,Thr,Val,Gly,Tyr,Asp,Ser,Ala,Pro,TEAA and TNEAA in broilers.Regardless of the level of dietary oil,adding different concentrations of lipase in the diet can improve(P<0.05)the TD of Lys,Try,Arg,His,Leu,Phe,Thr,Gly,Cys,Tyr,Ser,Glu,Ala,Pro,TEAA and TNEAA compared with the control group,and linearly and quadratically increase(P<0.05)the TD of Ile,Val,Gly,Cys,Ser,and Pro,and the TD of Met has an increasing tendency(0.05<P<0.1)in broilers compared with those of control treatment.Dietary supplementation of 400 mg/kg lipase significantly increased(P<0.05)the TD of Lys,Tyr,Arg,His,Leu,Phe,Thr,Val,Gly,Cys,Tyr,Ser,Glu,and Pro in broilers.Effects of lipase on growth performance,meat production and intestinal microbes:640 Arbor Acres(AA)broilers were selected,using 2×2 factorial design,2 fat diets(3%duck oil vs.3%soybean oil)and 2 lipase levels(0 and 200 mg/kg),randomly divided into 4 treatments with 8 replicates of 20 broilers.The experiment lasted for 42 d,and the broilers were fed a starter diet from d 1 to d 21 and a grower diet from d 22 to d 42.Average daily gain(ADG),average daily feed intake(ADFI),and feed-to-weight ratio(F/G)were measured during the test.In tests 21 days and 42 days,8 chickens were slaughtered for each treatment to measure the meat production performance and intestinal microbes.Results:Compared with control treatment,supplementation of lipase can increased(P<0.05)the 22 to 42 days and 1 to 42 days of average daily gain,and the body weight at 42 days of age,and reduced(P<0.05)22 to 42 days and 1 to 42 days of F/G of broilers.There was no significant difference in the growth performance of broiler chickens between different oil diets(P>0.05).Compared with the control treatment,supplementation of lipase can improve(P<0.05)the carcass yield,half chamber rate,eviscerated rate,breast rate and thigh rate of broilers in duck and soybean oil diets.Supplementation of lipase can improve(P<0.05)the total number of acid-producing bacteria on the 21 days and 42 days,and significantly reduced(P<0.05)the total number of E.coil on the 21 days and 42 days in duck and soybean oil diets.In conclusion,supplementation of lipase can increase(P<0.05)the utilization of conventional nutrients,amino acids and energy in broilers,and there is a gradient effect with the increase of lipase.Dietary supplementation of 400 mg/kg lipase is the most suitable addition amount.The addition of lipase in the diet of duck oil and the diet of soybean oil can improve the production performance and meat product performance of broiler,and improve intestinal tract health. |
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