Digestive System And Growth Of Culter Alburnus In Khanka Lake

Culter alburnus in Khanka Lake, commonly known as Xingkai white fish, is a geographic populations mainlydistributed in Heilongjiang Khanka Lake. Due to the unique geographical and water environment,culter alburnus inKhanka Lake form a separate species, physiological traits,and generally associated with Oncorhynchus keta andTribolodon brandti calling the "three frontier treasures".because of years of predatory fishing,the water level droppedand environmental destruction,wild populations are gradually reduced.Thus,Artificial breeding develops rapidly inorder to conserve fish resources and continues to meet the needs of people.Culter alburnus in Khanka Lake hasbecome an important breeding object in the northeast area especially Heilongjiang Province.The level of intensivefarming model of culter alburnus in Khanka Lake is closely related to the of study in artificial diets.While the researchof digestive physiology and growth is the base of studing and developing the artificial feeds,and feeding reasonablely.This thesis,morphometric and biochemical methods were employed to research the larveand juvenile of Culter alburnus in Khanka Lake,the studing contents contained the activity of digestive enzymes andalkaline phosphatase,and intestinal development, every age（age1to4）group’s digestive tube index,relativefatness,the distribution of digestive enzyme activities,and correlation between age and body weight.Results are asfollows:1. In the process of the development of the larve and juvenile of Culter alburnus in Khanka Lake,digestive enzymesand alkaline phosphatase were showing a different trend with the increasing of days under different enzymes, andshowed some volatility.Overall,after emergence from6-day-old fish,larvae of various digestive enzyme activitiesshowed upward trend except lipase activity.which protease activity fluctuated and followed by a steady increase in6-day-old to10-day-old,after20days of age, the rate of increase had slowed down;amylase activity in6-day-old to11-day-old showed a slightly downward trend, followed by activity increased steadily;With the age increasing, the larveand juvenile of Culter alburnus in Khanka Lake’s lipase activity showed a gradual downward trend, and finallystabilized at a certain level. While it’s alkaline phosphatase activity was showing a growing trend,there’s rapid growingacceleration from6-day-old to18-day-old and this growing acceleration showed down after18-day-old.2. Viscerasomatic index in the four age groups of culter alburnus in Khanka Lake,age1’s slowest,age2to age4showed downward trend, Hepatosomatic index showed a downward trend and Intestinal length index showed anupward trend with increasing age.The above clouddescripedthe growing rate of the visceral mass is greater than theweight from age1to age2,and this period was mainly through the ingestion of large amounts of food to meet theirgrowth and development. Viscerasomatic index and viscerasomatic index were relatively lower from age2growing to age4,this time,the fish body would improve own digestion and utilization rate of feed to meet the energy for thedevelopment.3. On the whole,foregut’s and midgut’s protease activity were sizable, hindgut’s protease activity were followed,andliver-pancreas’s protease activity were minimum.The protease activity of all digested tissue increased with age by age2to age4.The digestive tube of culter alburnus in Khanka Lake was the major organ.Overall,All digested tissue’samylase activity gradually increased with increasing age, and its lipase activity were successively themidgut,hindgut,foregut and iver-pancreas,and lipase activity showed elevated gradually with increasing age.4. Apower function relationship between body length and body mass of culter alburnus in Khanka Lake from age1toage4: W=0.022L^2.818（R²=0.989）, where b=2.818,was closed to3, indicating the culter alburnus in KhankaLake generally belong to the uniform growth of fish. A power function relationship between body length and bodymass of culter alburnus in Khanka Lake from age1to age2:W=0.047L^2.339（R²=0.966）,where b=2.339, wasmuch smaller than3, descriping the larval of culter alburnus in Khanka Lake in age1to age2were strongallometric.Apower function relationship between body length and body mass of culter alburnus in Khanka Lake fromage3to age4:W=0.010L3.049（R²=0.936）, where b=3.049,was basically the same to3,indicating that withincreasing age Culter alburnus in Khanka Lake’s allometric growth weakened, development trended uniform.Fatnesselevated from age1to age4. The analysis considered that the absorption of nutrients was mainly used for juvenilebone growth, the growth of the fish body length greater than the growth of the body weight in larval stage,so theyounger had lower relative fatness,but this is more conducive to the growth of the fish late rate, laid the foundation forthe formation of appropriate late body,as the development of fish body,body height and body width would grow fasterthan the growth of body length.