| 1.Exp.1 Effects of different proportion of rapeseed meal and cottonseed meal on growth performance, plasma biochemical indices and gossypol residues of carp (Carassius auratus gibelio)An 8-week feeding experiment was conducted to evaluate the effects of different proportion of rapeseed meal (RSM): cottonseed meal (CSM) on growth performance, hematological index and gossypol residues of Carassius auratus gibelio. Six diets were fed to fish with average weight of 5.6g.The ratios of RSM : CSM in diets (the total inclusion of RSM and CSM was 60%) were designed as 5:0, 4:1, 3:2, 2:3, 1:4 and 0:5. The results showed that weight gain(WG),feed efficiency ratio (FER) and specific growth rate (SGR) of Carassius auratus gibelio first increased,then decreased with the ration of RSM : CSM changing from 5:0 to 0:5. Fish fed with diet of RSM: CSM=3:2, had the highest weight gain (WG, 505.6%), condition factor and lowest feed conversion ratio (FCR, 1.33), hepatosomatic index. However fish fed with diet of RSM: CSM=5:0, had the lowest weight gain (WG, 430.1%), condition factor, and highest feed conversion ratio (FCR, 1.52), hepatosomatic index. No significant difference among treatments were observed in survival rate and muscle moisture, crude protein, crude lipid, crude ash content (P>0.05). Plasma ALT and AST activities of RSM: CSM=5:0 group were significantly higher than that of group of RSM: CSM=3:2, or 2:3 (P<0.05); AKP activities of fish of RSM: CSM=3:2 group had the highest value in all groups.There was no significant difference in plasma TP in all groups (P>0.05). Free gossypol content in muscle and liver increased with the rise of cottonseed meal content in diet (P<0.05). This study showed that the ratio of RSM and CSM for 3:2 was the optimal ratio for growth of Carassius auratus gibelio.High inclusion of rapeseed meal or cottonseed meal in diet would reduce growth performance and increase plasma ALT and AST activity.2.Exp.2 Effects of gossypol-acetic acid on growth performance, serum biochemical indices and toxin residues of carp (Carassius auratus gibelio)The present experiment was conducted to evaluate the effects of adding gossypol-acetic acid in diets on growth performance, serum biochemical indices and gossypol residues of Carassius auratus gibelio. The concentration of gossypol-acetic acid in experimental diets was 0mg/kg, 300 mg/kg and 900 mg/kg respectively. Experimental fish with average weight of 31.68±0.01g were fed the three diets for 8 weeks. The results showed that growth performance of Carassius auratus gibelio declined with the increase of supplemental gossypol-acetic acid. Compared with control fish, weight gain of fish fed with supplemental 300mg/kg, 900mg/kg gossypol-acetic acid diet was decreased by 8.43%,12.22%(P<0.05),and FCR increased by 7.69%(P>0.05),14.69%(P<0.05). Fish fed with 900mg/kg gossypol-acetic acid diet had the lowest condition factor and highest hepatosomatic index. No significant difference were observed in survival rate and muscle moisture, crude protein, crude lipid, crude ash content among treatments (P>0.05).In the serum biochemical indicators, the activity of AST, ALT, CREA in the group of adding 900 mg/kg gossypol-acetic acid was increased by 13.01%, 38.87%, 9.70%(P<0.05), and the activity of ALP, TP significantly decreased compared with control group (P<0.05). No significant difference among treatments were observed in serum UREA、TC、TG、T-Bil、Glu and Ca (P>0.05). Free gossypol content in muscle and liver increased with the rise of acetic acid gossypol content in diet (P<0.05).Free gossypol content was increased by 14.87%, 30.57% in muscle, and 26.23%, 57.84% in liver by dietary 300 mg/kg,900mg/kg gossypol-acetic acid (P<0.05).This study showed that weight gain of fish fed with 300mg/kg gossypol-acetic acid diet were reduced significantly and no significant difference were observed in the serum biochemical indicators. When supplemental gossypol-acetic acid reached 900mg/kg, weight gain of fish were further reduced and FCR were increased significantly. Serum activity of AST and ALT in the group of adding 900mg/kg gossypol-acetic acid also were increased significantly, which showed that liver may be affected by high level of dietary free gossypol.3. Exp.3 Effect of dietary microcapsule amino acids and protease AG supplementation on growth performance of carp (Carassius auratus gibelio)The present experiment was conducted to investigate the effect of crystalline amino acids and protease AG supplementation on growth performance of Carassius auratus gibelio.Five diets were prepared, which were high fish meal with 10% fish meal; low fish meal with 5% fish meal; low fish meal diet added with microcapsule lysine and methionine which had the same lysine and methionine content as low fish meal diet; low fish meal diet added with protease AG 175mg/kg;and low fish meal diet added with microcapsule amino acids and protease AG..Experimental fish with average weight of 31.68±0.01g were fed the five diets for 8 weeks.The results showed that weight gain and feed conversion ratio of fish fed with high fish meal diet were 187.4% and 1.43 respectively which was the best among five groups. However, weight gain and feed conversion ratio of fish fed with low fish meal diet were 158.14% and 1.70 respectively which was the worst among groups. Compared with low fish meal group, weight gain of microcapsule amino acids group, protease AG group and microcapsule amino acids + protease AG group increased 12.14%, 10.06% and 13.54%(P<0.05), feed conversion ratio decreased 11.18%, 8.8% and 11.76%(P<0.05), respectively.There were no significant difference in growth performance among high fish meal group, microcapsules amino acids group, protease AG group and microcapsule amino acids + protease AG group(P>0.05). In the serum biochemical indicators, no significant difference among treatments were observed in serum AST、ALT and ALP (P>0.05).After fish feeding the first three diets, serum total free amino acids and total protein concentration were determined at different time periods. Serum total free amino acids of microcapsule amino acids group, high fish meal group and low fish meal group kept consistent trend. The highest concentration of total free amino acids occurred at 3h after feeding. And serum total protein kept similar trend. This study showed that growth performance of Carassius auratus gibelio could be improved by adding microcapsule amino acids and protease AG in low fish meal diet. |
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