两种养殖密度下稻田宽体金线蛭生产效益分析

Growth Performance and Economic Benefit of Leech Whitmania pigra Cultured at Two Stocking Densities in a Rice Field

将当年繁殖的同一批初始体长(2.63±0.24)cm、初始体质量(2.46±0.27)g的宽体金线蛭养殖在89.55 hm^2稻田中,以每块稻田环形沟面积计,密度分别为50尾/m^2和100尾/m^2,每组3个平行。放养后第10 d开始定时、定位、定质、定量投喂中华圆田螺,每5 d按119 kg/hm^2投喂,研究两种密度下宽体金线蛭的生长及效益。50 d的养殖试验结果显示,100尾/m^2组宽体金线蛭的最终体质量、特定生长率和质量增加率显著减小(P<0.05);50尾/m^2组宽体金线蛭各生长参数显著高于100尾/m^2组(P<0.05);两种养殖密度下水稻产量差异不显著(P>0.05),不考虑水稻效益,100尾/m^2组养殖密度宽体金线蛭的平均净产值(69791元/hm^2)显著高于50尾/m^2组(57015元/hm^2)(P<0.05)。研究结果表明,50尾/m^2有利于促进宽体金线蛭的生长,但大规模养殖时,100尾/m^2养殖密度可取得更好的经济效益。

This study was designed to determine growth performance and economic benefit of juvenile leech Whitmania pigra with initial body length of(2.63±0.24)cm and body weight of(2.46±0.27)g cultured at two stocking densities in a rice field.The leech juveniles from the same batch were reared in a 89.55 hm^2 rice field at stocking density of 50 ind/m^2 and 100 ind/m^2 and fed snails at feeding rate of 119 kg/hm^2 every 5 days after 10th day after stocking for 50 days with 3 replicates in each group to investigate the effects of two densities on growth and benefit of leech juveniles.The results showed that the leech juveniles had significantly lower final body weight,specific growth rate and weight gain rate at higher stocking density than the juveniles at low stocking density did(P<0.05),and that the growth parameters were shown to be significantly higher than at high stocking density(P<0.05),without significant difference in rice yield(P>0.05).However,there was significantly higher economic benefit at high stocking density(69791 yuan/hm^2)than at low stocking density(57015 yuan/hm^2)(P<0.05),excluding rice economic benefit.The findings indicate that it is advisable to control the density of the leech juveniles at 100 ind/m^2,which is conducive to obtain higher economic benefits,even though good growth of leech is observed at 50 ind/m^2.