| Exp.1 Effects of pelleted and extruded diets supplemented with xanthophylls and oxidized soybean oil on growth and body color of channel catfishThe objective of this study was to investigate the effects of extruded and pelleted diets with xanthophylls and oxidized soybean oil on body color of channel catfish. Eight diets were prepared in the study, i.e. basal diet(control diet), basal diet supplemented with 100mg/kg xanthophylls, basal diet containing oxidized soybean oil(20g/kg), basal diet containing oxidized soybean oil(20g/kg) and supplemented with 100mg/kg xanthophylls, which were prepared by pelleting or extruding, and fed to channel catfish with average body weight of(60.0±0.2)g for 42 days. The results showed that there were no significant differences in growth among treatments, but the value of the yellowness of dorsal skin and xanthophylls content in skin, muscle of fish fed different xanthophylls were significantly higher than those of control group(P<0.05).While the value of the yellowness of dorsal skin of oxidized soybean oil group was significantly higher than the control group. There were not significant differences in the yellowness of muscle between oxidized soybean oil group and control group. In conclusion, xanthophylls was still account for the yellow colored channel catfish, oxidized soybean oil had effect on the skin color. NO significant differences were found between pelleted and extruded diets groups(P>0.05).Exp.2 Effects of practical diet with copper on growth and body color of channel catfishIn the present study, copper(as the form of Cu SO4·5H2O) with the levels of 0(control), 5, 10, 15, or 20 mg/kg were supplemented in a practical diet which contained 11.1 mg/kg Cu to formulate five diets to evaluate the effects of dietary Cu on growth and body color of channel catfish(Ictalurus punctatus). The five experimental diets were fed to channel catfish with average body weight of(98.1±0.5)g for 42 d. Each diet had 3 replicates, and each replicate had 20 fish. The results showed that weight gain rate was significantly increased and feed conversion ratio was significantly decreased by the supplementation of 10 mg/kg copper when compared with control group(P<0.05), but with the copper supplemental level increased to 40 mg/kg, the weight gain rate was significantly decreased and feed conversion ratio was significantly increased compared with 10 mg/kg group(P<0.05). The copper content in liver and bone was increased with the increase of dietary copper supplemental level, the liver copper content in 20 and 40 mg/kg groups was significantly higher than that in control group and 5 mg/kg group(P<0.05), and the bone copper content in 40 mg/kg group was significantly higher than that in control group(P<0.05),while the muscle copper content showed no significant difference among all groups(P>0.05).The chroma values and total xanthophylls content of dorsal skin, muscle and tyrosinase activity of dorsal skin of channel catfish were not significantly affected by 0 and 40 mg/kg copper supplementation(P>0.05).Serum aspartate aminotransferase(AST), alannine aminotransferase(ALT) activities and total bilirubin(T-Bil)content, and muscle moisture, crude protein, ether extract and ash contents were not significantly different among all groups(P>0.05).The activity of serum copper, zinc-superoxide dismutase in 10 mg/kg group was the highest, and significantly higher than that in other groups(P<0.05),but no significant difference was found among other groups(P>0.05).Based on results above, the optimal copper supplementation in the practical diet is suggested to be 10 mg/kg for channel catfish under this experimental condition, and the measured value of dietary copper content is 20.2 mg/kg. Exp.3 Effects of replacement of fishmeal by spray-dried blood cells on channel catfishThe present study was designed to evaluate the effects of fishmeal substitution with spray-dried blood cells on growth, body composition, body color, blood biochemical parameters, tissue Fe, Cu deposition in channel catfish(Ictalurus punctatus) with an initial body weight of( 49.9±0.2) g. Five diets were formulated to equally proportionally replace FM(FM content in the basal diet is 8%)with 0,2%,4%,6%,8% spray-dried blood cells. The feeding experiments lasted for 8 weeks. The results showed that weight gain rate was significantly increased by the replacement of 6% spray-dried blood cells when compared with the control group(P<0.05). While the feed conversion ration showed no significant among all the groups(P>0.05). The blood glucose(GLU) content was increased with the elevated spray-dried blood cells level(P<0.05), and triglyceride(TG) was decreased with the increase of spray-dried blood cells level(P<0.05). There were no significant differences in serum aspartate aminotransferase(AST), alannine aminotransferase(ALT) activities and total cholesterol(CHOL), total protein(TP)and albumin(ALB) content.The iron content in liver was increased with the elevated dietary spray-dried blood cells(P<0.05), while the muscle iron and liver iron, copper content showed no significant different among all the groups(P>0.05).In addition, the chroma values of dorsal skin, muscle and tyrosinase activity of dorsal skin of channel catfish, and moisture, crude protein, ether extract, ash contents of the whole body were not significantly different among all the groups(P>0.05). Based on the above all, the optimal dietary substitution level was 6% under this experimental condition. |
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