Physiological Response Of Leiothrix Lutea In High Temperature

With the influence of global warming,extreme high temperature weather happened more frequent,posing a huge threat to the survival of living things.Birds are an important member of the ecosystem.The physiological response of Leiothrix lutea under high temperature conditions was discussed in this paper.Experiment 1:Leiothrix lutea was placed in 30? for 28 days,and the body weight and metabolic rate were measured at 0 day,14th day and 28th day,respectively.Experiment2:Leiothrix lutea divided into 5 groups randomly control group?30??,1D group?40?,1 day?,3D group?40?,3 days?,14D?40?,14 days?and recover?adapted to 40? for 14 days then adapted 30? for 14days?,and measured the indicators of metabolic thermogenesis and oxidative stress after completion of adaptation.Experiment 3:Leiothrix lutea divided into 3 groups randomly control group,14D and recover?processing method is the same as experiment 2?,and measured the body fatty and indicators of fatty acid metabolism.The main results are as follows:?1?There were no changes in body weight and BMR during constant temperature adaptation,which indicated that the control group in experiments 2 and 3 could be used as a reference for other experimental groups.?2?In order to maintain the normal body temperature in the long-term high temperature treatment,the thermogenesis at the body,organ and cell levels were reduced,which lead to the reduction of energy consumption.The gross energy intake?GEI?,feces energy?FE?,digestible energy intake?DEI?and energy digestibility decreased.After a period of recovery,the levels of metabolic heat production and body weight of the Leiothrix lutea have returned to normal levels,so energy intake increased.In addition,the activity of liver antioxidant enzymes and the mRNA expression of HSP₇₀ were increased to prevent high temperature stress.However,long-term high temperature treatment still led to an increase in Malondialdehyde?MDA?content and a decrease in muscle avUCP expression,indicating that long-term high temperature caused oxidative damage in the body,and it did not recover during the14-day recovery period.?3?After long-term high temperature treatment,the body fat content was significantly reduced.In the same time,the activities of fatty acid metabolism enzymes in the liver and muscle and the expression of FABP-pm in the liver decreased.This indicates that the reduction of energy consumption leaded to a decrease in fatty acid metabolism and fat supply.After recover,the activity of CPT-1 in the liver was significantly decreased,the mRNA expression of fatty acid transport protein in the heart was increased,which showed that the fatty acid metabolism of the liver was decreased in liver,but the fatty acid metabolism was enhanced in heart.This suggests that there are differences in fatty acid metabolism in various organs.All results indicated that Leiothrix lutea can reduce the thermogenesis and increase the antioxidant level to adapt to high temperature for 14 days,but it still caused oxidative damage.Meanwhile,because of the reduction of energy requirements,fatty acid metabolism is reduced to reduce fat supply.The results of the recovery group showed that the plasticity of thermoregulation was more significant than that of antioxidants in high temperature.