Effects Of Dietary Replacement Of Fishmeal By Soybean Meal And Feeding Strategy On Gibel Carp

The present study was to evaluate the effect of replacement of dietary fishmeal by soybean meal on gibel carp (Carassius auratus gibelio) and the feeding strategies used to improve the utilization of the diet with soybean meal. Three 16-week growth trials were conducted under similar experimental conditions, and soybean meal was used to replace 0 (Control, D1), 20% (D2), 80% (D3), 100% (D4) of dietary fishmeal protein. Experimentâ… was to investigate the effect of replacement of dietary fishmeal protein by different levels of soybean meal protein on gibel carp. In Experimentâ…¡andâ…¢, different feeding strategies were tested to improve the utilization of the diets with soybean meal as main protein source in gibel carp. There were two periods in Experiment II: during first period (week 0-8), the effect of different levels of soybean meal on growth performance was investigated, and, during the second period (week 9-16), repeat feeding with the control diet and tested diets with soybean meal was used to test the effect of feeding strategy on fish. In Experimentâ…¢, during the first 8 weeks, the effect of different levels of soybean meal replacement on growth performance was investigated, and during the week 9-16, the fish were all fed the control diets to investigate the effect of re-feeding fish with high quality diet on growth performance.The results are shown as follows:1) With the increasing inclusions of dietary soybean meal, feeding rate (FR), specific growth rate (SGR), feed conversion efficiency (FCE), protein retention efficiency (PRE) and energy retention efficiency (ERE) in gibel carp decreased significantly. Apparent digestibility coefficient of protein (ADCp) significantly increased (P < 0.05), while ADCd and ADCe decreased (P < 0.05).2) Plasma glucose and triacylglycerol concentration and superoxide dismutase activity increased, while plasma cholesterol concentration and plasma lysozyme activity decreased significantly with the increase in dietary soybean meal (P < 0.05).3) Fish liver and intestinal histology was not affected by the inclusion of dietary soybean meal.4) In Experimentâ…¡, FR increased while SGR, FCE, PRE and ERE decreased with the increase in dietary soybean meal during the week 0-8 (P < 0.05). With the change of feeding strategy during 9-16 weeks, fish final body weight of group D2, D3 and D4 was lower than D1 (the control) (P < 0.05). During the week 9-12, SGR of D2 was lower than other groups (P < 0.05); During 13-16 weeks, there were no difference among all treatments in SGR (P > 0.05). D4 was higher than D3 and D2 in SGR (P < 0.05), suggesting that there was partial compensatory growth in D3 and D4 when changing feeding regime. FCE, PRE and ERE decreased with the increase in dietary soybean meal (P < 0.05). FR was ranked in the order: D4 >D3 >the control >D2 during the week 9-12 (P < 0.05), during the week 13-16, D3 and D4 were higher than the control and D2 in FR (P < 0.05), D4 was significantly higher than D3 in FR (P < 0.05).5) After repeat feeding fish with the control and tested diets, plasma glucose level of the control group was lower than D2 (P < 0.05), and no difference between D3 and D4. Plasma triacylglycerol concentration increased, but plasma cholesterol level and lysozyme activity decreased with the increase in dietary soybean meal (P < 0.05). Superoxide dismutase activity of D4 was higher than other groups.6) In Experimentâ…¢, FR increased while SGR, FCE, PRE and ERE decreased during the week 0-8 with increased dietary soybean meal (P < 0.05). When fish was re-fed with the control diet, there was partial compensatory growth in D3 and D4, and complete compensatory growth in D2. SGR and FR increased with increased dietary soybean meal during previous feeding (P < 0.05). During the week 9-12, FCE in D4 group was lower than that in the control (P < 0.05). During the week 13-16, there was no significant difference between D4 and the control in FCE (P > 0.05). When the fish were re-fed the control diet (fish meal protein), PRE and ERE were improved and no difference between all treatments during the total experimental period.7) With increased dietary soybean meal in previous stage ( the week 0-8), fish plasma glucose concentration showed slight increase (P > 0.05); plasma triacylglycerol concentration increased (P < 0.05) ; plasma cholesterol concentration and superoxide dismutase activity showed no significant difference, plasma lysozyme activity gradually decreased (P < 0.05).