| With the increasing development of China’s aquaculture industry,many new green aquaculture models have emerged,and the land-based recirculating aquaculture model is one of them.This mode is an intensive and efficient breeding mode in which the predatory fish are concentrated and housed in a circular breeding barrel set on the ground and coupled with the tail water treatment and recycling system.In this paper,in order to investigate the effects of different density culture on growth performance in land-based culture system,juvenile gibel carp Carassius gibelio var.CAS V was used as the experimental object,and to comprehensively analyze the economic benefits of the whole seedling cultivation period,so as to provide basic technical parameters for the breeding mode.The experiment was set up in high density group(0.3 kg/m~3)and low density group(0.15 kg/m~3).Each experimental group was equipped with 3 parallel buckets,and the fish were cultured for 160 days.The growth indexes of fish and physiological and biochemical indexes related to serum,muscle and liver were determined.The results are as follows:After 160 days of breeding,the final body weight(FW),final body length(FL)and fatness(CF)of the gibel carps were significantly increased in the LSD group,and the WGR also showed similar result(P<0.05).The feed coefficient(FCR)was higher in the HSD group.There was a negative correlation between the SGR and the SD.Through the histological observation of white muscle,it was found that the density of white muscle fibers in LSD was significantly increased(P<0.05).By m RNA relative expression level measurement,UPS related genes ub,psma2 and mafbx were significantly expressed in the high density group,and m TOR pathway related gene s6k1 was significantly expressed in the low density group.The expression levels of MRFS-related genes and igf-1r were significantly increased in low density group.During the whole culture period,the water temperature of the two density groups kept the same,and the p H value gradually decreased.The dissolved oxygen in the high density group was lower overall.The content of tristate nitrogen was higher in the high-density group as a whole,and there were significant differences between the two groups at individual time points.The contents of alanine aminotransferase(ALT)and Cortisol in serum of the gibel carp were significantly increased in the high density group.The content of malondialdehyde(MDA)in the liver was significantly expressed in the high density group(P<0.05),and the activity of related antioxidant enzymes was not significantly different between the two density groups.The m RNA expression levels of keap1 et al in dorsal white muscle were significantly higher in high-density group(P<0.05).After the end of breeding,the economic benefit of breeding was analyzed,and it cost1111 yuan and 666.6 yuan to buy fries in a single high density and low density breeding barrel respectively,and 919.8 yuan and 744 yuan in feed cost in high and low density breeding barrels.The electricity cost in both groups is 1080 yuan,and the labor cost was2666.67 yuan/barrel.The cost of animal protection products for single high density and low density buckets was 416.67 yuan and 250 yuan,respectively.According to the price of the breeding local fries 30～40 yuan/kg sold,high density barrel income 6528 yuan,low density barrel income 6250 yuan.Therefore,the net income of the gibel carp breeding barrel of high-density was 333.87 yuan,and the return rate of investment was5.39%;The net income of the gibel carp breeding barrel of low-density group was 842.73yuan,and the rate of return on investment was 15.59%.After 160 days of fries cultivation,the water quality in the land-based barrel of low-density group was good,and the growth of the gibel carp was good,and the growth rate was significantly increased.Suitable stocking density can improve the FCR and SGR of the gibel carp,increase muscle fiber density,enhance oxidation resistance,promote muscle formation and improve the economic benefits of culture. |
PDF Full Text Request