Effect of Acute Low Temperature Stress on Oxygen Consumption Rate and Respiration Frequency in Silurus meridionalis and Pelteobag vachelli

The objective of the study was to explore the effect of acute low temperature stress on VO2 and Vf of Silurus meridionalis and Pelteobag vachelli after 10 minutes cold water bath with different temperature.The investigation was operated under the temperature of 24 ℃.It was found that the VO2 and Vf of Silurus meridionalis after 6 and 0 ℃ stress showed a decrease-increase-decrease trend while other groups showed a rapid increase then slowly recovery trend.The VO2 and Vf of Pelteobag vachelli after 0 ℃stress showed a decrease-increase-decrease trend while other groups showed an increase then slowly recovery process.It was suggested that Pelteobag vachelli was more adaptive to acute cold stress,but it cost more energy adapting to cold stress compared to Silurus meridionalis.

Dietary xanthophyll improved growth,antioxidant,pigmentation and meat quality in the southern catfish(Silurus soldatovi meridionalis Chen)

Xanthophyll has multiple physiological functions to improve the quality of farmed animals.The present study aimed to investigate the effects of xanthophyll on the growth performance,antioxidation,immunity,pigmentation and meat quality of southern catfish(Silurus soldatovi meridionalis Chen).Juvenile southern catfish(18.35±0.04 g)were randomly allocated into 24 cages(30 juveniles per cage),and fed diets with different dietary xanthophyll levels(at 14,42,80,108,126 and 152 mg/kg,dry matter of diet)twice daily for 8 weeks.Results indicated that the diet with 80 mg/kg xanthophyll induced a higher specific growth rate(SGR),feed efficiency ratio and protein productive value.Moreover,the 80 mg/kg xanthophyll diet also increased complement 3,immunoglobulin M(IgM)and lysozyme content more than the other groups.The mRNA expression level of inflammation-related genes and antioxidant enzyme activities further confirmed the effects of 80 mg/kg dietary xanthophyll on improving immune response.The present study also found that the 126 mg/kg xanthophyll diet significantly enhanced the content of total carotenoids and xanthophyll,hydroxyproline,collagen and amino acid in muscle.The diet with 126 mg/kg xanthophylls also induced lower drip loss,thawing loss,centrifugal loss,cooking loss and higher muscle adhesiveness,cohesiveness,springiness,gumminess and chewiness than the other treatments.In conclusion,quadratic regression model analysis based on SGR and IgM revealed that the optimum xanthophyll level in the diet was 86.78 and 84.63 mg/kg,respectively.Moreover,broken line regression analysis based on xanthophyll content in dorsal skin and chewiness in muscle demonstrated that the optimal xanthophyll level was between 89.73 and 108.66 mg/kg in the diet of southern catfish(S.soldatovi meridionalis Chen).