| This study used the iron cage culture technology to compare the effects of Scylla paramamosain to the breeding traits,nutrition composition and the soil physical and chemical properties in mangrove and light beach.The seedlings crab's weight is 11.78 ± 2.40 g.There were4 experimental groups of Scylla paramamosain respectively.(1)The light beach no bait group(2)The light beach bait group(3)the mangrove no bait group(4)the mangrove bait group.Three parallel repetitions were designed for each experimental group and each parallel repetition has 5crabs,with fresh and small fish as bait.The specification of the iron cage(length,width and height)is 1m x 0.8m x 0.4m,and the iron cage is separated by four iron plates,forming five independent spaces.The size of each space is 0.2m x 0.8m x 0.4m,and the individual farming mode is adopted.The breeding period was 60 days.At the end of the experiment,the number of living individuals and the measurement of their weight,shell width and shell length were carried out.The nutrition composition of muscle was determined.The main results are as follows:1.The breeding traits: the mangrove bait group,the light beach bait group,the mangrove no bait group,the light beach no bait group compare after capture.The average weight at the end is(83.36±7.14)g?(76.00±7.05)g?(42.99±9.39)g and(19.54±3.10)respectively,and the weight gained 6.87,6.25,3.32 and 1.32 times respectively.The meat rate was 30%,29%,22%and 20% respectively.The fatness is 0.64,0.64,0.63 and 0.60 respectively.The survival rates were 40%,40%,33.3% and 20% respectively.The four groups of the bait breeding methods are better,and the mangrove bait group is optimal.2.Nutrition composition: the crude protein content of each group was high(77.00-80.14 %),and the crude fat content was low(0.91-1.73 %),which was consistent with the nutritional characteristics of high protein and low fat.Mangrove grow two experiments crab's crude protein content is higher than light beach two groups and pond farming group and crude fat below breeding two groups and pond farming group,close to the mangrove wild group.The total amino acids of the experimental crabs in each group between 68.03-76.10 %,the total content of essential amino acids between 31.25-35.53 %,and the total amount of non-essential amino acids between 36.80-40.57 %.The ratio of essential amino acids to total amino acids is 45.22-47.29%,and the ratio of essential amino acids to non-essential amino acids between 84.34-89.77 %.The total amount of flavor amino acids is 33.59-38.20 %,accounting for 48.35-50.20 %.The first limiting amino acid of Scylla paramamosain in different growth conditions was valorine or methionine + cystine;Amino acid branched to aromatic ratio is 1.87-2.02,close to egg proteinstandard.Six groups of amino acid composition of the best in the experiment of crab for mangrove wild group,the mangrove two groups of amino acids is superior to the light beach breeding two groups and pond farming group,near the wild group.The groups of experimental crab is rich in unsaturated fatty acids,monounsaturated fatty acid accounts for 8.80-13.60 %,total polyunsaturated fatty acids accounts for 37.34-41.14 %,both accounts for about 50 %,of polyunsaturated fatty acids EPA and DHA relative content is higher,accounting for about 30 %.The ratio of n-3/n-6 is more than 2.5,indicating that the fatty acid is nutritionally balanced and has good health function.The PUFA of the experimental crabs in each group,the mangrove bait group was the best.The PUFA of the two groups in the mangrove forest was better than that of the two light beach culture groups.3.Soil physical and chemical properties: different farming methods have influence on soil physical and chemical properties of soil depth between 0-10 cm and 10-20 cm,and the impact on soil depth 0-10 cm is greater than 10-20 cm of soil depth.The organic carbon,total phosphorus and total nitrogen content of soil were increased in each breeding experiment group,among which the effect of the mangrove bait group was most significant.The pH value and salinity were not significantly affected by the other breeding groups except for the mangrove bait group.The mangrove bait group can improve soil pH value significantly.In summary,compared with the light beach growth conditions,the mangrove cultured conditions is more advantageous in breeding traits and nutrition composition,and can improve soil fertility and promote the growth of mangrove forests.The results of the study can solve the contradiction of mangrove restoration planting and local fishermen tidal flats breeding,can enhance the economic income of local fishermen,and can better protect mangrove,realize the sustainable development of mangroves. |
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