| Largemouth bass(Micropterus salmoides)and mandarin fish(Siniperca chuatsi)are two famous aquatic products whose demand in my country has been increasing year by year in recent years.The main production areas are in the south,of which 60%of largemouth bass and 30%of mandarin fish are produced.From Guangdong Province.Guangdong Province is located at the junction of tropical and subtropical regions.In winter,it will experience a short period of low water temperature(10-16℃).Under this low temperature condition,no feeding(starvation)or a small amount of feeding is usually used for overwintering in aquaculture.The two physiological states of hunger and feeding fish under low temperature stress are still a blind spot.Based on this breeding status,this study carried out a comparison of short-term hunger and feeding physiological states of largemouth bass and mandarin fish under low water temperature and largemouth bass under low water temperature.The physiological dynamics of short-term starvation in largemouth bass and mandarin fish.To provide a reference for the research and development and feeding management of winter overwintering feed,four experiments are set up as follows:1.Comparison of the physiological status of short-term hunger and feeding of largemouth bass under low water temperatureIn the experiment,90 largemouth bass(84.18±0.33)g body weight(84.18±0.33)g were selected under low water temperature(13±1℃),and they were randomly divided into 2 groups with 3 replicates in each group and 15 fish in each replicate.15d)and the feeding group(feeding 15d).After the experiment,various physiological and biochemical indicators were measured.The results showed:1)The body mass,weight gain rate,protein deposition rate,fat deposition rate,liver glycogen,The crude fat content of whole fish and muscle was significantly lower than that of the feeding group.The weight gain rate of the feeding group was 5.46%,while the weight loss rate of the hungry group was 3.29%.2)The number of blood neutrophils,alkaline phosphatase activity,triglycerides,total cholesterol,high-density lipoprotein,low-density lipoprotein and triglyceride levels of the starving group of largemouth bass were significantly lower than those of the feeding group,but the starving group The plasma alanine aminotransferase and aspartate aminotransferase activities of largemouth bass were significantly higher than those of the feeding group,and most of the other blood physiological indexes of the two groups were not significantly different.3)The digestive enzyme activity,liver and gill antioxidant capacity of the starving group of largemouth bass were significantly lower than the feeding group,while the liver lipid metabolism enzyme activity of the starving group was significantly higher than that of the feeding group.4)The plasma lysozyme activity and IgM content of largemouth bass in the hungry group were significantly higher than those in the feeding group,while the spleen IgM of the hungry group was significantly lower than that in the feeding group.There was no significant difference in the kidney IgM content between the two groups.2.Physiological dynamics of short-term starvation of largemouth bass under low water temperatureIn the experiment,270 largemouth bass weighing(84.18±0.33)g were randomly divided into 6 groups with 3 replicates in each group and 15 fish in each replicate.They were starved at low water temperature of(13±1℃)for 0,3,6,9,12 and 15 days.the physiological and biochemical indexes were measured respectively,and the results showed:1)The body mass,fullness,liver-to-body ratio,visceral-to-body ratio,muscle fat and protein content of largemouth bass all vary with The prolonged starvation time showed an overall downward trend,while the muscle ash content showed an opposite trend.Among them,the weight of largemouth bass decreased by 0.49%,2.12%,2.51%,2.71%and 3.33%respectively on the 3rd,6th,9th,12th and 15th day after starvation.2)The activities of alanine aminotransferase and aspartate aminotransferase in the blood of largemouth bass show a trend of decreasing first and then increasing with the prolonged starvation time,reaching the minimum on the 3rd day,and the blood glucose content remains stable after a sharp drop on the 3rd day of starvation,and the rest of the blood biochemistry The indicators show a gradual downward trend.3)Most of the digestive enzyme activities of largemouth bass first increased and then decreased with the prolonged starvation time,reaching the maximum on the 6th day of starvation,while the amylase activity had no significant difference in the first 9 days of starvation,and then decreased significantly.4)The antioxidant capacity of the liver of largemouth bass increased first and then decreased with the prolonged starvation time,and reached the highest value on the 6th day of starvation.The activity of liver lipid metabolizing enzymes all decreased first and then increased with the prolonged starvation time.3.Comparison of physiological status of short-term hunger and feeding of mandarin fish under low water temperatureIn the experiment,under low water temperature(13±1℃),90 mandarin fish with body weight(84.13±0.14)g were selected,and they were randomly divided into 2 groups,each with 3 replicates,each replicate with 15 fish,and the two groups were starved groups(starved for 15 days)And the feeding group(fed for 15 days).After the experiment,various physiological and biochemical indicators were measured.The results showed:1)The body mass,weight gain rate,protein deposition rate,fat deposition rate,liver glycogen,whole fish and fish in the starvation group The crude protein and crude fat content of the muscle was significantly lower than that of the feeding group.The weight gain rate of the feeding group was 7.01%,and the weight loss rate of the hungry group was 9.16%.2)The number of blood neutrophils,alanine aminotransferase and aspartate aminotransferase activities,total cholesterol and low-density lipoprotein content of the hungry group of mandarin fish in the hungry group were significantly higher than those in the feeding group,but the blood alkaline phosphatase activity and triglyceride of the mandarin fish in the hungry group The content of ester and high-density lipoprotein was significantly lower than that of the feeding group,and there was no significant difference in blood physiological indexes between the two groups.3)The digestive enzyme activity,immune capacity,liver and gill antioxidant capacity of the starving group of mandarin fish were significantly lower than those of the feeding group,while the activity of lipid metabolism enzymes in the liver was significantly higher than that of the feeding group.4.Physiological dynamic changes of short-term starvation of mandarin fish under low water temperatureIn the experiment,270 mandarin fish weighing(84.13±0.14)g were randomly divided into 6 groups,with 3 replicates in each group,15 fish in each replicate,and starvation(0,3,6,9,12,15)d,respectively determine the physiological and biochemical indicators,the results show:1)With the extension of starvation time,the body mass,fullness,liver-to-body ratio,visceral-to-body ratio,and muscle protein of the mandarin fish were prolonged.Both body weight and fat content showed a gradual downward trend.Among them,the body weight decreased greatly.The 3rd,6th,9th,12th,and 15th days of starvation decreased by 3.03%,3.82%,5.55%,7.68%,8.39%respectively compared with 0d.2)Starvation caused alanine aminotransferase and aspartate aminotransferase in the blood of mandarin fish to decrease first and then increase,reaching the minimum value on the 3rd day of starvation,while other blood biochemical indicators showed an overall downward trend.3)The activity of amylase in mandarin fish was stable in the early stage of starvation,and decreased in the later stage,and the activities of other digestive enzymes gradually decreased with the prolonged starvation time.4)As the starvation time prolonged,the antioxidant capacity of the liver of mandarin fish first increased and then decreased,reaching an inflection point on the 6th day of starvation.In summary,the following conclusions are obtained:1.Under low water temperature,short-term hunger for largemouth bass and mandarin fish mainly uses fat and liver glycogen for energy.Starvation can induce and enhance the blood immune level of largemouth bass,but the immunity of mandarin fish is reduced,and it is against the digestive system and liver of the two fish The tissue structure and function of the fish are negatively affected;however,short-term food intake can promote the growth and nutrient accumulation of largemouth bass and mandarin fish,and protect the digestive system and liver.2.Under low water temperature,short-term starvation of largemouth bass and mandarin fish will negatively increase their body mass,size and liver will shrink,muscle protein and fat content will decrease,largemouth bass digestive enzyme activity,antioxidant capacity,and mandarin fish’s antioxidant capacity will all be hungry The inflection point is reached on the 6th day,and the digestion and antioxidant capacity of both fish will be impaired when they continue to starve.3.A comprehensive comparison of the changes in physical indicators,muscle composition,blood biochemical indicators,and digestive enzyme activities when faced with short-term starvation in largemouth bass and mandarin fish under low water temperature,the results show that compared with mandarin fish,largemouth bass is more resistant to hunger and is suitable The starvation time has a significant effect on the liver antioxidant capacity of the two fishes. |
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