The Effect Of Low Temperature Stress On Growth,muscle Composition And Hematological And Biochemical Indices Of Tilapia (oreochromis Niloticus × O.aures)

This paper aimed to investigate the influences of low temperatures stress on growth,biochemical,hematological and biochemical indices,the activities of lysozyme,SOD,CAT of tilapia(Oreochromis niloticus×O.aures)under the controllable environment indoor. Six treatments were designed as 25℃(controls),18℃,16℃,14℃,12℃,11℃. Experimental results show that:1. Low temperature had significant effects on growth in tilapia(Oreochromis niloticus×O.aures)The lowest temperature for feeding is 14℃. The fish had no feeding in 12℃and 11℃in this experiment. The lowest temperature for survive is 11℃and they can only survive for 14 days. There were more or less decreased in every group, compared with the control,a significant decrease of growth in 12℃and 11℃because of effect of low temperature stress and starvation. The growth of 11℃dropped significant after low temperature stress for 14 days(P<0.05), and the growth of 16℃,14℃,12℃decrease significant in the end of experiment. All groups'Relative fatness had significant decreased in the beginning, there were significant differences between all groups and controls except 18℃(P<0.05). All groups had significant decreased compared with control,especially in 12℃and 11℃. There were more or less decreased in HIS and VSI of every group compared with control, especially in 12℃and 11℃.2. Low temperature stress had significant effects on muscle composition of tilapia(Oreochromis niloticus×O.aures)(P<0.05).Muscle protein and fat tend to decreased after low temperature stress. Compared with control, all treatment groups had significant decreased (P<0.05). Muscle protein and fat decreased with decreased temperature. Muscle water and ash tend to increased continuously with time continuing, and had significant increased in the end of experiment (P<0.05). These two indexes increased with decreased temperature. The result shows that the muscle protein and fat was used as energy materials.3. In this paper, the RBC,HGB,HCT of all treatment groups had significant decreased compared with control(P<0.05),and had different fluctuations with time continuing. But all groups had significant decreased except18℃in the end of experiment. The MCH tend to increase continually, and significant higher than control in the end of experiment. The MCV was significant different between all groups in 7th and 14th day (P<0.05). The group of 18℃and 16℃had significant lower than control in 7th day(P<0.05), and only 18℃had significant lower than control in 14th day(P<0.05). In the end of experiment, there is no significant different between all groups and control.The activities of enzymes ALT and AST increased continually following the prolonging of low temperature stress time. The activities of enzymes ALT of all treated groups are significantly higher than control croup in the end of experiment. The activities of enzymes AST of all treated groups is significantly higher than control croup in 21th day. The result shows the liver was harmed by low temperature stress.The concentration of total protein,albumin tend to increase, then decrease. The concentration of total protein is significantly lower than control group (P<0.05). The other group is not significantly different with control group. While the concentration of albumin of all treated groups are significantly lower than control group in the end of experiment except 18℃group.The concentration of cholesterol decreased in the beginning. All groups increased continually following the prolonging of low temperature stress time except 11℃group. The group 12℃is still significantly lower than control group in the end, while the other groups are no significant difference with control group.The concentration of triglycerides of all groups is significantly lower than control group in the beginning. Then every group had different fluctuations, but is tent to increase generally. The group of 18℃,16℃,14℃are significantly higher than control group in the end of experiment, while the group of 12℃is significantly lower than control group.The concentration of glucose decreased continually following the prolonging of low temperature stress time. But the glucose increase from 14th day. The group 12℃is significantly higher than control group(P<0.05), while the other group is not different with control group.4. After the experiment of low temperature stress, the significant effect on immune enzymes activities was observed.The super oxide dismutase and catalase belongs to antioxidant enzyme. In this experiment, the activities of antioxidant enzyme are significantly higher than control after low temperature stress in the beginning. Then the activities of antioxidant enzyme are increased continually following the prolonging of low temperature stress time. The activities of antioxidant enzyme of all groups are significantly higher than control group (P<0.05). The activity of super oxide dismutase of group 11℃is significantly lower than control group in 14th day, while the activity of catalase increase to normal level. The activity of lysozym of group 18℃,16℃is decreased in the beginning, and the group 18℃is significantly lower than control(P<0.05), while the groups of 14℃,12℃,11℃are significantly higher than control(P<0.05). In the end of experiment, all groups are recovering to normal level.