Digestive Tube Development And The Activity Distribution Of Three Kinds Of Digestive Enzymes Of Ctenopharyngodon Idellus Fed On Different Diets

There are three different dietary phases during larval development of Grass carp:Carnivory, dietary transition phase and herbivory. In the present experiment, GrassCarp were fed on Chironomus tentans (Group A) or Lemna minor (Group B) for onemonth, treatments were arranged as completely randomized design. The effects ofdifferent dietary treatments on the growth, digestive tube development, digestiveenzyme activities were studied. Using RT-Real Time PCR, the pattern of BSAL geneexpression during larval development in liver was determined.We found that dietaryappears to play a significant role in growth and digestive tract indices: Group Btended faster growth (P<0.05) compared to Group A treatments, also the length gainrate(LGR), Weight gain rate(WGR) and Specific growth rate(SGR) were higher thanGroup A, with insignificant difference among the experiment groups(P<0.05).Theratio of intestine gut length to body length of Group B was higher than Group A, andsignificant difference was observed among the experiment groups(P<0.05); while theratio of intestine weight to body weight and liver weight to body weight of Group Bwas higher than Group A, with insignificant difference among the experimentgroups(P<0.05). The specific activity of protease of Group B was higher than GroupA, but difference of protease activities were insignificant under two treatments(P>0.05). The specific activity of lipase of A group was higher than B group,difference of lipase activities was significant in liver (P<0.05), but insignificant inintestine (P>0.05). The specific activity of amylase of Group A was higher than GroupB, with significant difference in intestine(P<0.05), but insignificant in liver(P>0.05).The BSAL gene got higher expression in Group A than Group B, insignificant inliver(P>0.05). In the dietary transition phase, herbivorous grass carp have a role inpromoting growth and digestive tube development, and digestive enzyme activitiesand gene expression are adapted to the corresponding dietary pattern of grass carp.