Study On The Evaluation Of Metabolic Energy Of Muscovy Duck Diet By Simulative Digestion Method

According to the physiological parameters of Muscovy ducks under captive conditions,the main digestive enzyme activities,electrolyte ion concentration and p H value of jejunum under different dietary metabolizable energy and crude protein levels were obtained as the theoretical basis for enzyme and buffer systems in the two-step digestive enzymatic method,and explore the simulate digestive parameters of Muscovy duck,then,the in vitro method was compared with the in vivo emptying method and the Peking duck in vitro method to determine the feasibility of the in vitro method for assessing the metabolizable energy value of Muscovy duck,provides a certain technical support for evaluation feed metabolizable energy value of Muscovy duckThis study is divided into two parts:The first part is to explore the simulate digestive parameters of Muscovy ducks,including the intestinal digestive parameters of Muscovy ducks and the optimal digestive time of Muscovy ducks.The Exp.1 was was carried out with a single factor completely random design,setingm 6 ME levels are 11.0 MJ/kg,11.5 MJ/kg,12.0 MJ/kg,12.5 MJ/kg,13.0 MJ/kg and 13.5 MJ/kg;6 crude protein levels are 14.0%,15.5%,17.0%,18.5%,20.0%and 21.5%,a total of 12 treatments.Six replicates were performed for each treatment,with 3 ducks for each replicate.To explore the effects of dietary metabolic energy level and crude protein level on the main digestive enzyme activity,ion concentration and p H of the empty intestinal fluid of adult male Muscovy duck.The second part is to explore the optimal digestion time in the intestinal period.The measured rectal temperature of Muscovy duck was used as the simulate digestion temperature.According to the digestion parameters determined in Exp.1,the intestinal digestion time was set as 12 h,15 h,18 h and 21 h,to explore the influence of different digestion time on the SDGE,SYGE and SDDM.The second part is to explore the feasibility of the simulate method to assess the metabolizable energy value of Muscovy duck,including the comparison between Muscovy duck simulate method and biological method,and the comparison of simulate method between Muscovy duck and Peking duck.Both experiments were performed using a single factor completely randomized design.The experiment collected 26 samples of energy feed ingredients such as corn,sorghum and barley,protein feed soybean meal,cottonseed meal and rapeseed meal,respectively.In the comparative experiment of biological method,the second experiment selected one of the six kinds of feeds to carry out the simulate contrast test of Muscovy duck and Peking duck,and explored the feasibility of the biomimetic method to evaluate the metabolizable energy value of Muscovy duck.The experiment results showed that:（1）Dietary ME level had significant effect on chymotrypsin activity（P<0.05）,but no significant effect on amylase and trypsin activity.The ME level had a significant effect on the concentration of Ca²⁺,K⁺,Mg²⁺and p H values（P<0.05）,but had no significant effect on Na⁺and Cl^-（P>0.05）.Dietary protein level had significant effects on the activities of amylase,trypsin,chymotrypsin,Ca²⁺concentration and p H value（P<0.05）,but had no significant effects on the concentration of Na⁺,K⁺,Mg²⁺and Cl^-（P>0.05）.The optimal digestion parameters were as follows:for energy feeds,the amylase activity was 307.26 U/m L,the trypsin activity was 54.68 U/m L,the chymotrypsin activity was 24.9U/m L,and the Na⁺and K⁺concentrations were 104.39 mmol/L and 14.21,respectively.Mmmol/L,p H value was 7.79;for protein feed,amylase activity was 381.88 U/m L,trypsin activity was 72.84 U/m L,chymotrypsin activity was 11.98 U/m L;Na⁺and K⁺concentrations were 93.53 mmol/L and 13.70 mmol/L,p H value was 7.80.（2）The simulative digestion temperature of Muscovy duck was 41℃.The SDGE,SYGE and SDDM were significantly affected by the digestibility time of corn and soybean meal in the intestinal phase（P<0.05）,but the indexes were stable with the extension of time in the range of 15-21 h,so the optimal digestibility time of the bionic digestibility intestinal period of duck was 15 h.（3）For the 13 energy samples,there was no significant difference between 9 samples of SDGE and their AME.For 13 protein samples,8 samples had no significant difference between SDGE and TME.The coefficient of variation of AME,TME and ADDM measured by biological method is above 1%,and the three are mainly distributed between 1%and 5%.The proportion of AME in this interval is 73.08%.The proportion of TME in this interval is80.77%,and the proportion of ADDM in this interval is 65.28%.Compared with biological methods,the main distribution intervals of coefficient of variation are within 2.5%,and the ratio of SDGE in this interval is 84.6%,and the proportion of SDDM in this interval is96.15%;for the estimation deviation,the estimated deviation of 20 feed samples from SDGE to TME is less than 10%.From the results,the test accuracy of the bionic method is higher than that of the biological method.For energy feeds such as corn,sorghum and barley,the biomimetic digestion method can estimate the quantitative level of apparent metabolic energy;for protein feeds such as soybean meal,cottonseed meal and rapeseed meal,the simulate method can estimate the quantitative level of true metabolic energy.（4）Through the comparative experiment of Muscovy duck and Peking duck,it was found that the SDGE,SYGE and SDDM of Muscovy ducks and Peking ducks were significantly different（P<0.05）.Therefore,it was necessary to establish simulative digestion procedures for Muscovy ducks.To sum up,the bionic digestion method can achieve the quantitative level of estimating the metabolic energy value of Muscovy duck feed,and its accuracy is higher than that of the tube-feed method.