| How to achieve efficient feeding for the cultured fish under the mode of recirculating aquaculture system is not only a difficult problem in production management,but also a key scientific problem to be solved in the realization of welfare farming.At present,the feeder used in China generally has problems such as poor precision,low intelligence and poor stability.In order to solve such problems,this paper took Micropterus salmoides as the research object,and cited a quantitative method of fish feeding activity based on the characteristics of water flow field.Then the quantitative analysis of the feeding activity of Micropterus salmoides were done,and the quantitative results were taken as the basis for determining the hunger status of the fish.At the moment,based on the quantitative results,the corresponding feeding strategy was formulated.Based on this,an adaptive feeder for circulating aquaculture system was designed and developed.And the actual feeding effect was studied by comparing with the traditional feeder which feeding time and amount are required to set done.The specific research content and results are as follows:Aiming at the culture characteristics of recirculating aquaculture system,a method for quantifying the feeding activity of fish based on the characteristics of water flow field was cited,and its suitability for quantifying the feeding activity of Micropterus salmoides was studied.Studies had shown that under four different gastrointestinal satiety indices(0.36±0.04,1.21±0.12,1.45±0.17,1.85±0.21),the quantitative results of the feeding activity of the Micropterus salmoides were compared with the CVFAI function and the SBCS function.The results show that this method achieves better quantization than the other two,that is,the method cited is applicable to Micropterus salmoides.However,the disadvantage is that when the culture object is too small or the culture density is insufficient to stir the water to achieve the change of the water surface reflective area or the reflection area is not significantly changed,the method is no longer applicable.Based on the above-mentioned quantification method for Micropterus salmoides feeding activity,an adaptive feeder for indoor recirculating aquaculture system was designed and developed.It mainly included the design of feeding device,track structure and feeding control system,as well as hardware selection and prototype trial and debugging.The designed feeder adopts a timing and variable feeding amount method,and it is not necessary to set a specific feeding amount.The feeding amount is determined by the feeding activity of the fish in the current feeding process,and feeder can judge the feeding amount of each meal to meet the needs of the fish.The adaptability of the feeder in the actual process of recirculating aquaculture was explored,and Micropterus salmoides was taken as experimental object,then the culture experiment was carried out by comparing with the traditional feeder which feeding time and amount are fixed.After the experiment,the growth,physiology and immunity of Micropterus salmides of the two feeding methods were analyzed and studied.And the results are as follows:(1)Adaptive feeding method can better meet feeding needs of Micropterus salmoides,reduce feed waste,and weaken the classification phenomenon.(2)There was no significant difference in the survival rate,hepatosomatic index and condition factor between the two feeding method(P>0.05).However,in terms of weight gain rate,the adaptive group was 30.17%higher than the traditional group(P<0.05),in terms of feed conversion rate,the adaptive group was reduced by 0.21 compared with the traditional group(P<0.05),in terms of specific growth rate,the adaptive group is 0.22%higher than the traditional group(P<0.05).The results show that adaptive feeding method has a faster growth rate,so it is better than the traditional method.(3)There were no significant differences in cortisol,superoxide dismutase and malondialdehyde between the groups(P>0.05),but in terms of lysozyme,the traditional group was 4.73 nmol/mg higher than the adaptive group(P<0.05).From the results of(1)and(2),the traditional group can not meet the feeding needs of fish well,causing a short-term hunger state and stimulating the lysozyme activity.(4)There was no significant difference in water,ash and crude fat content between the groups(P>0.05),in terms of crude protein content,the traditional group was 3.99%higher than the adaptive group(P<0.05).(5)There was no significant difference in the activities of liver amylase,intestinal amylase,liver lipase,intestinal lipase,liver protease and intestinal trypsin between the groups(P>0.05),in terms of pepsin activity,the adaptive group was 1.64 U/mg higher than the timed quantitative group(P<0.05),indicating that under this feeding mode,the stomach of the fish is more strongly digested by the protein,which is more conducive to the digestion and absorption of the protein in the feed,which is more conducive to growth. |
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