The Research Of Nutritional Assessment, Digestive Enzyme Activity And Gastrointestinal Histology In Perca Flavescens

In this experiment, the Perca flavescens whose weight was (142.29±4.31) g were theresearch objects, national standard method was used to measure the general nutrition andevaluate their muscle nutritional value; anatomical and histological methods were used toresearch the morphology and structure of the digestive tract in Perca flavescens; at the sametime, enzyme technology was used to study digestive enzyme activity of various tissues andorgans in Perca flavescens. The results showed that:1、The moisture content was77.91%, the crude protein content was18.62%, the crude fatcontent was1.21%,the ash content was1.26%in muscle of Perca flavescens. The total contentof amino acids was84.07%(mass fraction,dry sample), among which essential amino acids was36.66%, accounting for43.62%of total amino acids, the proportion of essential amino acidcomposition in line with the United Nations food and agricultural organization (FAO)/WorldHealth Organization (WHO) standard. In Perca flavescens,the ssential amino acid index (EAAI)was62.57%, the non-essential essential amino acid (NEAA) was42.06%,and the deliciousamino acids (DAA) was33.14%. Ca, Mg, Zn and other essential minerals were reach in themuscle of Perca flavescens.2、 Digestive tract and digestive glands constitute the digestive system of Percaflavescens,the digestive tract consists of oral-pharyngeal cavity, esophagus, stomach, intestineand anus, the liver is the largest digestive gland of Perca flavescens. The average ratio betweenthe weight of intestine and body was0.60±0.31, the average ratio between the length of intestineand body was0.72±0.12in Perca flavescens. The gastric mucous layer can be divided intomucosal epithelium and mucosal lamina propria, mucosal epithelial contains a large number ofcolumnar cells and a small amount of goblet cells, gastric gland cells mainly located in themucosa lamina propria. The intestine tract of Perca flavescens can be divided into submucosa,mucoa, muscularis and serosa, intestinal mucosa to enteric Cavity formed many folds, intestinalepithelium composed by columnar cells and goblet cells, and columnar cells were abundance.The muscle of stomach and intestinal were both smooth muscle. The digestive morphology andhistology of Perca flavescens were adapted to their feeding habits.3、The activities of all digestive enzymes of each digestive organs in Perca flavescensincreased at first and then decreased with temperature increasing in the designed temperature. Instomach and liver, the optimal temperature for protease were both40℃, whereas in pyloric caeca,anterior intestine and middle intestine were50℃; The optimum temperature for amylasein stomach, middle intestine and liver were35℃,in anterior intestine and pyloric caeca wereboth30℃. The optimum temperature for lipase in different digestive organs of Percaflavescens was40℃.4、The activities of digestive enzymes of the five digestive organs in Perca flavescensincreased at first and then decreased with PH increasing in the designed PH.In stomach, pyloriccaeca, anterior intestine, middle intestine and liver of Perca flavescens, the optimum pH forprotease were2.5,8.0,9.0,9.0and6.0,respectively; the optimum pH for amylase were6.0,6.0,7.0,7.0and6.0, respectively; the optimum pH for lipase were6.0,7.0,7.0,7.0and7.0respectively.