| Exp.1 Effects of protease suppleme ntation in low fish meal pelleted and extrude d diets on growth, nutrie nt retention and digestibility of gibel carp, Carassius auratus gibelioThe present study was conducted to evaluate the effects of exogenous protease supplementation in low fish meal pelleted and extruded diets on growth, nutrient retention and digestibility, and serum biochemical indices of gibel carp, Carassius auratus gibelio. A high- fishmeal(HF) diet containing 9% fish meal and a low-fishmeal(LF) diet containing 3% fish meal(6% fish meal was isonitrogenously replaced by soybean meal) were designed as the positive and negative control diet, and 125, 150 and 175 mg/kg exogenous protease were supplemented in the LF diet, respectively. The five formulas were then processed with pelleting and extruding, respectively, to obtain ten diets. After the pelleting a nd extruding, the retention rate of the protease activity was 77.98% and 37.65%, respectively. The diets were fed to gibel carp with an initial body weight of 35.0±0.2 g for 12 weeks. In pelleted diets, the supplementation of 150 and 175 mg/kg protease in LF diet significantly improved weight gain, nutrients apparent digestibility coefficients(dry matter and crude protein), nutrients retention(crude protein and crude lipid) and decreased feed conversion ratio(FCR) when compared to negative control(P<0.05), and showed the similar values as the positive control(HF group). In extruded diets, despite no significant differences in growth, nutrients digestibility and retention among treatments, fish fed diet supplemented with 150 mg/kg protease showed numerically highervalues than fish fed the negative control diet(P<0.10). When comparing the extruded diets and the pelleted diets, fish fed extruded diets had significantly higher body lipid level and lipid retention than fish fed pelleted diets, and the fish fed extruded diets except the HF diet showed the significantly higher protein retention than fish fed pelleted diets with the same formulation, respectively. There were no significant differences in serum triglycerides, total cholesterol and glucose levels among all groups, and no significant differences in serum total protein and albumin levels among groups except the extruded HF group. The above results showed that the supplementation of 150 and 175 mg/kg protease in pelleted LF diet, but not in extruded LF diet, could improve the growth performance, nutrient digestibility and nutrient retention of gibel carp when compared to the pelleted LF diet without protease. Exp.2 Effects of organic acid salt blend and protease supplementation in fish meal free diet on growth, nutrie nt retention and digestibility of Jian carp, Cyprinus carpio var. JianThe present study was conducted to investigate the effects of organic acid salt blend and protease supplementation in fish meal substituted diet by meat and bone meal o n growth performance, nutrient retention, and serum biochemical indices of Jian carp, Cyprinus carpio var. Jian. A positive control(PC) diet containing 6% fish meal and a negative control(NC) diet containing 0% fish meal(fish meal was totally replaced by meat and bone meal,and then coated lysine and coated methionine were added) were formulated. 325 mg/kg organic acid salt blend(OAB), 175 mg/kg protease(Pr) and 325 mg/kg OAB+175 mg/kg protease(OAB+Pr) were added to the negative control diet, respectively to form another three experimental diets. Jian carp with an initial body weight of 90.0±0.3 g were fed one of the five diets with triplicate of 18 fish in each cage for 9 weeks. The results showed that p H of diets and chyme in proximal and middle intestine at 0.5h, 1h and 2h after feeding were not significantly different among treatments(P>0.05). Growth performance, digestibility of dry matter and crude protein and nutrient retention of fish fed NC diet were significantly lower than those of fish fed PC diet(P<0.05). Supplementing OAB increased 8.9% weight gain of fish(P<0.05) and FCR had a decreasing trend(P>0.05); Growth performance of fish fed Pr and OAB+Pr diet showed a improved trend, but not significant(P>0.05); digestibility of dry matter and crude protein of the OAB, Pr and O AB+Pr groups were numerically higher than the NC proup, and displayed not significant difference with PC group(P>0.05). The three additition groups exhibited no significant effect on whole-body composition except that the OAB+Pr group showed significantly higher whole-body phosphorus content than the NC group. Retention of protein, lipid and phosphorus and serum antioxidant capacity of fish fed OAB diet were significantly higher than fish fed NC diet(P<0.05); supplemental protease improved retention of protein and lipid(P<0.05), but no significant effect on phosphorus retention or serum antioxidant capacity was observed(P>0.05); phosphorus retention and serum antioxidant capacity of fish fed OAB+Pr diet were significant ly higher than fish fed NC diet(P<0.05), and improvement on retention of protein and lipid was not significant(P>0.05). In conclusion, replacing fish meal by meat and bone meal decreased growth performance and nutrient digestibility of Jian carp significantly; adding OAB improved weight gain significantly and showed positive but not significant effects on FCR and nutrient digestibility for Jian carp. Supplemental protease or combination of OAB and protease only displayed a trend of improvement on growth a nd nutrient digestibility. Exp.3 Effects of organic acids supplementation in fish meal free diet on growth, nutrie nt retention and digestibility of Jian carp, Cyprinus carpio var. JianThe present study was conducted to investigate the effects of fish mea l replacement by meat and bone meal with dietary organic acids supplementation on growth, nutrient rerention and digestibility and serum biochemical indices of Jian carp, Cyprinus carpio var. Jian. A positive control(PC) diet containing 6% fish meal and a negative control(NC) diet in which fish meal was totally substituted by meat and bone meal were prepared, and 0.25% citric acid, malic acid, fumaric acid and sodium butyrate were supplemmented to the NC diet. Jian carp with an initial body weight of 90±0.3 g were fed with one of the 6 diets in triplicate for 9 weeks. The results showed that p H of chyme in proximal intestine of citric acid group at 0.5 h after feeding was numerically lower than control groups(P>0.05). Jian carp fed NC diet showed significantly lower growth performance, apparent digestibility of dry matter and crude protein and retention of protein, lipid and phosphorus compared to fish fed PC diet(P<0.05). Both the supplementation of citric acid and malic acid significantly improved weight gain and retenion of protein, lipid and phosphorus and decreased feed conversion ratio(P<0.05), and showed the similar values with the PC group(P>0.05), meanwhile, citric acid supplementation increased digestibility of dry matter and crude protein significantly(P<0.05). However, supplemental fumaric acid and sodium butyrate displayed not signiciant influence on growth performance, nutrient digestibility and retention of Jian carp(P>0.05). No significant differences on moisture, crude protein, crude lip id, crude ash or phosphorus content of whole body were observed(P>0.05). Serum antioxidant capacity of fish was improved significantly by citric acid, malic acid and sodium butyrate supplementation compared with fish fed PC and NC diets(P>0.05). There were no significant differences on total protein, albumin, glucose, triglyceride and total cholesterol contents of serum among treatments(P>0.05). In conclusion, supplementation of 0.25% citric acid or malic acid to diet in which fish meal was replaced with meat and bone meal could improve growth performance, nutrient retention and serum antioxidant capacity of Jian carp, and nutrient digestibilities were significantly increased by citric acid supplementation, however, no significant effects on these indicators were observed by 0.25% fumaric acid or sodium butyrate supplementation. |
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