Effects Of Water Temperature, PH And Fodder On Feeding Behavior And Meat Quality Of Red Swamp Crayfish (Procambarus Clarkii)

The red swamp crayfish (Procambarus clarkia) is one of the main economic animals, how to use the comprehensive technology such as the environment optimization and nutrition strengthen to improve the productivity is becoming the main topic for farming as the increase of the consuming market and the farming scale of the crayfish. The illumination, substrate, dissolved oxygen, temperature, salinity, chemicals and fodder has an important influence on the feeding behavior of the crayfish and further affect the its growth and meat quality in the process of intensive farming. Therefore, this paper chose the temperature, pH and fodder as affecting factors to study their influence on the feeding behavior, growth and muscle quality of the crayfish, determined the optimum farming condition and supplied the basic dada for the farming crayfish. The results showed as following:1) The water temperature had the influence on the feeding behavior of the crayfish for three kinds of fodders (compound fodder, maize and fish). The intake of the crayfish for three kinds of fodders was followed as the temperture increased. To the compound fodder, the feeding rate of the crayfish at 5℃ was lower than that of the other groups and there was no significant difference among the other groups; it was highest at 25℃ and 30℃ than those for other groups; it firstly was less and finally higher than those of 15℃ and 20℃ groups at 35℃. To the maize fodder, there was no significant difference for the feeding rate of the crayfish between the different groups at 5℃; the crayfish had the same feeding rate at 15℃ as 20℃ and 25℃; it had the highest feeding rate at 30℃ and there was no significant difference between the different groups at 35℃. To the fish fodder, there was significant difference between the all groups at 5℃; the feeding rate of the crayfish at 30℃ was higher that those for 15℃、20℃ and 25℃ and there was no difference between other groups; it was higher at 35℃ than that at5℃ and lower than those for other groups. The crayfish decreased the activity at 5℃ and 35℃ and stopped the feeding activity. The death of the crayfish happened at 35℃。2) The crayfish had different feeding behavior for three kinds of fodders (compound fodder, maize and fish) under different pH gradients. The crayfish for three kinds of feed intake first increased and then decreased at the increase of pH. To the compound fodder, the feeding rate of the crayfish was higher at pH6.7 and pH6.5 than that for other groups, it increased at the beginning and then decreased at pH7.5, and it was lower at pH5.5 and pH8.0 than that for other groups. To the maize fodder, the feeding rate of the crayfish was higher at pH6.7 and pH6.5 than that for other groups, there was no significant difference between all groups at pH7.5, and it decreased at the beginning and then became stable at pH5.5 and pH8.0. To the fish fodder, the feeding rate of the crayfish was the highest at pH6.7, then was followed by pH6.5, pH5.5, pH7.5 and pH8.0. Under the different pH condition, the mortality of crayfish was not the same, pH6.7 was the best condition for the lowest mortality rate of the crayfish.3) Seven different feeding methods of the three kinds of fodders had the influence on the growth of the crayfish during 98 days feeding cycle. The final body length was the longest for fodder groups as 7.43±0.09cm than for other groups and the final body weight was the highest for fodder+soybean groups as 21.26±2.04g than for other groups.4) The different feeding methods had influence on the physical quality of the crayfish meat. The meat rate of the crayfish for soybean+fish group was lower than that for other groups, the drip loss of the crayfish for soybean+fish group was higher than that for other groups and there were no significant difference between different groups for the cooking loss,tenderness,cooked meat rate and pH of the crayfish.5) The different feeding methods had influence on the contents of the inosine acid and free amino acid. They were 2.36±0.01mg/g and 277.55±2.19mg/g for fodder+soybean+fish group and were higher than those for other groups.The above results showed that the water temperature, pH and fodder for farming condition had the different influence on the feeding behavior, growth and meat quality of the crayfish. 30℃ and pH6.7 were the optimum condition for the crayfish feeding and the fish fodder had the best effectivity. The crayfish had the highest growth rate when it was fed the compound fodder+soybean. The contents of the inosine acid and free amino acid were the hightest for compound fodder+soybean+maize feeding method than that for other feeding method. This indicated that the mixed feeding method was better for growth and meat quality of the crayfish than that single feeding method.