| Measurements were made on biochemical components in muscles of Silurus Lanzhouensis which is endemic fish living in the mid-up reach Yellow River.Also,common feed protein resorce were evaluated and digestive physiology of Silurus Lanzhouensis were studied primarily.In order to confect compound feed,develop artificial breed , protect resource of Silurus Lanzhouensis effectually,and enrich basic data of feed nutrition and kinetics of digestive enzyme-catalyzed reactions. Method such as national standard were adopted to determine biochemical composition of muscles.According to amino acid pattern of muscles,the pattern of amino acid pattern of requirement were calculated. Adopt the grey relational analysis method to evaluate balance effect of amino acid of common feed protein for Silurus Lanzhouensis. Consult Weiqi Jiuxun's methods to determine the index of alimentary tract.Composition of food in alimentary tract were observed by eyes and dissecting glasses. Adopt exact indicator paper of pH to determine the pH values of stomach,anterior intestine,middle intestine,posterior intestine and bile. Apply the Folin-phenol reagent method,the Hypoiodic acid method and the Polyethephon-olive oil emulsion hydrolytic method to determine protease,amylase and lipase activities of stomach,anterior intestine,middle intestine,posterior intestine and bile under the condition of different temperature (15℃, 20℃, 25℃, 30℃, 37℃, 42℃a nd 47℃) , respectively.and that the effect of pH values(2.6,3.0,3.4,3.8,4.2,4.6,5.0,5.4,5.8,6.2,6.6,7.0,7.4)on activities of amylase and lipase enzymes of stomach, intestine and bile were studied. The results showed that:1. contents of crude protein,crude fat,ash and moisture of fresh muscle were 17.4±0.71%,2.22±1.09%,1.12±0.09% and 80.4±0.83% respectively.The composition of amino acids of muscle was 18,among which there were 8 essential amino acids for human needs.In dry sample,the total content amino acids was 72.289±3.708%;the content of essential amino acids was 30.238±2.18%;4 kinds of delicious amino acids accounted for 24.6%. Glu was the most abundant and Cys was the shortest in all amino acids of the muscle.The percentage of essential amino acids in total amino acids were 41.8%.The essential amino acids index (EAAI) was 69.30 and the constitutional rate of essential amino acids met FAO/WHO Standard.The limited amino acids of Silurus Lanzhouensis were Val,Leu and Ile.The composition of fatty acids in the muscle was found 4 saturated fatty acids and 9 unsaturated fatty acids.The amount of unsaturated fatty acids was 65.210%. C18:1 and C18:2 was main unsaturated fatty acids,which was 41.531% and 7.309% respectively.Minerals such as P,Na,K,Ca,Mg,Zn,Fe and Se were rich in these samples. The content of P was significently higher than other mineral elements(p < 0.05). In all elements,Zn was the richest microelment,which was 0.18 mg/kg(fresh),Fe and Se were secondary and tertiary microelment ,respectively,which was 8.31 mg/kg and 0.31 mg/kg.Furthermore,the ratio of Zn and Cu was not rational,so was Zn and Fe.The study indicated that Silurus Lanzhouensis is one of freshwater fishes with better nutritive value and raising value.2. The pattern of essential amino acid requirement were:Lys 21.092%,Met 6.327%,Trp 2.107%,Leu 14.387%,Ile 8.055%,Thr 9.718%,Phe 9.447%,Val 10.135%,Arg 13.508%,His 5.225%.3.The requirement of Lys and Met were higher than other amino acid, but two amino acids were main limited amino acids in common feed material. Contents of fish meal's essential amino acids were high ,and balance effect of that were best among all feed material in this studies.The balance effect of essential amino acids for full-fat soybeans,meat meal,rapeseed meal(exp. or sol.),soybeans, soybean meal(exp. or sol.),gelatin and sesame meal(exp.) were well and the contents of that were abundant too. The balance effect of essential amino acids for corn germ meal(exp.),alflfa meal,barley malt sprouts,wheat bran, wheat idling and red dog and rice bran meal(exp.) were well but the contents of that were not abundant.In addition, although the contents of essential amino acids for casein ,blood meal,feather meal,corn gluten meal,cottonseed protein,cottonseed meal(exp. or sol.) and leather meal etc.were abundant,the balance effect of that were not well.4.The ratio of intestine length to body length was 0.91±0.25,while the ratio of stomach,intestine,hepatopancreas and viscera weight to body weight were 0.0158±0.0045,0.0112±0.0054 , 0.0199±0.0069 and 0.0916±0.0293 respectively. The pH values of stomach,anterior intestine,middle intestine,posterior intestine and bile were 5.5-6.5,5.5-7.0,6.0-7.0 ,6.0-7.0and 5.5-7.0 respectively. Considering from the diet composition and character of digestive organs, the digestive and physical character of silurus Lanzhouensis Chen was conform with the character of carnivorous fish.5.with the increasing of temperature, the digestive enzymes'activities increased at first, then decreased. The optimum temperatures of the protease in all digestive tissues and organs were 42℃; those of amylase were 30℃except stomach ,which was 37℃; those of lipase were 25℃except posterior intestine, which was 30℃. The optimum temperatures of these enzymes were higher than the temperature that the fish lived in,which showed the protein of enzymes'thermostability. 6.Under respective optimum temperature and pH7.5, protease activity changed in the order from high to low as anterior intestine≈middle intestine>posterior intestine>hepatopancreas≈stomach; amylase activity changed as anterior intestine>middle intestine>hepatopancreas>stomach>posterior intestine; lipase activity changed as middle intestine>posterior intestine>anterior intestine≈hepatopancreas>stomach, which showed that anterior intestine and middle intestine are the main positions in digesting protein, also anterior intestine and middle intestine are the main positions in digesting amylace and lipid respectively. The activity of protease is higher than that of amylase in the temperature from 25℃to 37℃. The result also showed that the range of temperature for lipase to exert its activity was narrower than that of protease and amylase.7.The optimum pH values of stomach ,hepatopancreas and intestine for amylase were 5.4,6.6 and 7.0, and that for lipase were 5.4(or 5.8),6.6 and 6.6 respectively. The pH values in stomach and intestine are suitable for amylase and lipase. under the optimum pH value and (30±1)℃,the amylase activity in hepatopancreas was same as in intestine and that in approximately,stomach was the lowest.The lipase activity in stomach was higher than that in hepatopancreas and intestine, while the lipase activity in hepatopancreas and intestine was the same. |
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