| This paper,the effects of γ-aminobutyric acid(GABA)and guanidine acetic acid(GAA)on the alleviation of transport stress in juvenile koi were studied.First of all,the changes of physiological indexes of koi at different transport time points was measured to determine the transportation time of further experiment.Secondly,GABA and GAA were added to the water to explore the relieving effect of these two additives on transport stress indices of koi.In addition,GABA and GAA were added to thebasal diet and fed to fish for 8 weeks,and fish were transported at the end of the feeding experiment.The effects of γ-aminobutyric acid and guanidine acetic acid on the growth,immunity and anti-stress of koi were determined.It provides a new idea and research direction to relieving transportation stress of ornamental fish and to promoting the development of new feed additives.The main contents and results are listed as follows: 1.Effect of transport time on water parameters and stress indices of fish.A simulated transport experiment was carried out on a shaker.The body length of fish was 12.42 ±0.19 cmand the body weight was 13.04 g.Water quality and blood biochemical indexes were measured at 0h,4h,6h,12 h,24h and 48 h.The results showed that the p H value of the transport water decreased gradually as the transportation time increase.the p H value at 4 hours after transportation was 6.9±0.26,which was 0.3 lower than that before transportation(P < 0.05).After 48 hours of transportation,the p H value in the water decreased to 6.3,which was significantly lower than that before transportation(0hours)(P < 0.05).The concentration of ammonia nitrogen increasedas time increased,and the concentration of ammonia nitrogen at 4hours after transportation was nearly 4 times higher than that before transportation.The level of serum cortisol was significantly higher at 12 hours after transportation than that before transportation.The content of serum cortisolpeaked at 4 hours aftertransportation,which was significantly higher than that before transportation(0 hours).After 6 hours of transportation,the content of serum cortisol decreased.Similarly,the contents of serum epinephrine and blood glucose peaked at 4 hours after transportation,so the time of transport stress was determined to be 4 hours.2.The effects of adding γ-aminobutyric acid and guanidine acetic acid to water on transport stress of fish.5mg/LGABA,50mg/LGABA,150mg/LGABA,5mg/LGAA,50mg/LGAA and150mg/LGAA were added to the water,and without any additives as the control group,3replicates were set in each experimental group.The results showed that after 4 hours transportation,the p H value of the control group decreased to the lowest,and the concentration of ammonia nitrogen in the control group was significantly lower than that in the control group,except that the concentration of ammonia nitrogen in the 5mg/LGABA group was slightly higher than that in the control group.Among them,the concentration of ammonia nitrogen in150mg/LGABA group was the lowest,which was about 10 times lower than that in the control group.The concentration of ammonia nitrogen in the 150mg/LGAA group was more than 4times lower than that in the control group.After 4 hours of transportation,the serum cortisol of the control group was 165.38±1.02 ng/ml,wherea thatof the three treatment groups supplemented with GABA wasdecreased.The content of cortisol in 50mg/LGABA group was the lowest,which was nearly 3 times lower than that in the control group.supplementation with5mg/LGAA and 150mg/LGAA decreased the content of serum cortisol in koi,which was significantly lower than that in the control group(P < 0.05).However,50mg/LGAA did not decrease the content of serum cortisol.In addition,the addition of GABA and GAA in water decreased the content of blood glucose and epinephrine.The effect of GABA was better than that of GAA,and when the addition level of GABA was 50mg/L,the blood indexes decreased to the lowest.It is suggested that the addition of GABA and GAA to water can reduce the metabolism and cortisol content of koi,thus having the effect of anti-transport stress.3.The effects of γ-aminobutyric acid and guanidine acetic acid on the growth,immunity and anti-stress of fish.5mg/kg GABA,50mg/kg GABA,150mg/kg GABA and 5mg/kg GAA,50mg/kg GAA were added to the basic diet and fed to fish for 8 weeks.the results showed that the weight gain rate(WGR),specific growth rate and feed conversation rate were significantly increased by adding exogenous γ-aminobutyric acid(GABA)and guanidine acetic acid(GAA).When the addition level of GABA was in the range of 5-150mg/kg,the weight gain rate of fish in each experimental group increased with the increase of exogenous γ-aminobutyric acid,but it was significantly higher than that in the control group(P < 0.05).There was no significant difference in the level of GAA in the low dose group,but the weight gain in the 50mg/kg group was significantly higher than that in the control group(P < 0.05).The feed conversation rate of50mg/kg GABA group was the lowest,and the condition factor of 5mg/kg GAA group was higher than that of control group,but there was no significant difference among other groups.At the end of the feeding experiment,the transportation stress experiment was carried out.The expression of igf-1,ghr,il-10,tnf-α,lyz,sod and cat in liver,spleen and head kidney was determined by q PCR.The results showed that GABA and GAA could significantly increase the expression of growth genes such as igf-1 and ghr and promote the growth of fish.In general,the expression of il-10 and tnf-α in dietary GABA group increased slightly,but the effect was not significant.However,the relative expression of il-10 in the 50mg/kg GAA group was significantly higher than that in the control group,The expression of lyz gene in all experimental groups was lower,and significantly lower than that in the control group,The addition of GABA and GAA can significantly increase the relative m RNA expression of sod and cat.The effect of50mg/kg treatment group was the best. |
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