Study On The Effect Of Exogenous Protease On The In Vitro Energy And Amino Acid Digestibility Of Chicken Feed

The objective of this study was to determine the effect of exogenous proteases on the in vitro digestibility of gross energy and amino acid by a computer-controlled simulated digestion system to simulate the digestion in the gastrointestinal tract of chicken.The effects of exogenous proteases and sample weight on the in vitro digestibility of nutrients and energy was determined and the optimal amount of protease in the feed ingredients was observed.The effects of in vitro parameters on digestibility of nutrients and gross energy in the soybean meal with and without exogenous protease were also determined.The effects of exogenous proteases on the in vitro digestibility of nutrients and energy in the feed ingredients to provide a methodological reference for the rapid evaluation of the effectiveness of the feed enzyme.1.The objective of the Experiment I was to determine the effects of exogenous proteases and sample weight on the in vitro digestibility of nutrients and energy.Inclusion of exogenous proteases increased the in vitro dry matter digestibility(DMD),crude protein digestibility(CPD),gross energy digestibility(GED),amino acid digestibility(AAD),and enzymatic hydrolysable gross energy(EHGE)of soybean meal(P<0.05).In vitro nutrient digestibility of soybean meal with 1g of sample weight was significant greater than those with 2g of sample weight(P<0.01).The interaction effect of the exogenous proteases and sample weight on the EHGE of soybean meal was observed(P<0.01).The highest in vitro nutrient digestibility was observed in the 2500 mg/kg of exogenous protease and 1g of sample weight in the soybean meal.2.The objective of the Experiment II was to determine the effects of in vitro parameters(the concentrations,pH value and volume of simulated gastric fluid,the time of duration to simulate digestion in the stomach,and the site of action of the exogenous protease)on digestibility of nutrients and gross energy in the soybean meal with and without exogenous protease were also determined.The DMD and GED of soybean meal with exogenous protease increased as the time of duration increased to simulate digestion in the stomach and reached a maximum value at 240 min.The DMD and GED of soybean meal with exogenous protease increased(P<0.01)by decreasing the pH value or volume of simulated gastric fluid and reached a maximum value at the pH value of 2.0.The DMD and GED of soybean meal increased(P<0.01)by decreasing the volume of simulated gastric fluid and inclusion of exogenous protease reduced the DMD and GED of soybean meal(P<0.01).The DMD and GED of soybean meal increased as the concentrations of simulated gastric fluid increased and reached a maximum value by the 3100 U/mL of pepsin.Inclusion of exogenous protease increased the DMD and GED of soybean meal to simulate digestion in the stomach or small intestine(P<0.01).The DMD and GED of soybean meal with exogenous protease to simulate digestion in the small intestine were greater than in the stomach(P<0.01).3.The objective of the Experiment ? was to determine the effect of exogenous proteases on the in vitro digestibility of nutrients and energy in the feed ingredients.The DMD and GED of feed ingredients were not affected by the addition of 2500 mg/kg protease.The inclusion of 2500 mg/kg protease increased the apparent and standardized digestibility of Met in corn,DDGS,and cottonseed meal(P<0.05).The inclusion of protease increased the standardized digestibility of His,Ile,Leu,Lys,Phe,Thr,Val,Ala,Asp,Glu,Gly,Pro,Ser and Tyr in sugar beet pulp(P<0.05).