人工海水对罗氏沼虾幼体生长发育及能量收支影响初探

通过自制人工海水培育罗氏沼虾(Macrobrachium rosenbergii)幼体,与天然海水对比分析人工海水特性及养殖过程中的水质状况,探究人工海水对罗氏沼虾幼体生长发育及能量收支的影响。试验在广西南宁国家级罗氏沼虾良种场进行,罗氏沼虾幼体和饵料丰年虫无节幼体均由该良种场提供,罗氏沼虾幼体规格(湿重)为(1.476±0.050)g,共80万尾;在幼体开始培育前配制人工海水1 000 kg,配比为海盐:MgSO_4∶CaCl_2∶KCl∶H_3B_3O_3∶KBr∶ETDA∶生石灰=2000∶600∶72∶36∶24∶4∶1∶2;设置天然海水为对照组,试验组及对照组分别设置4个重复。结果显示,人工海水中,Mg~(2+)∶K~+∶Ca~(2+)=3∶1∶1,与北部湾天然海水接近,且水质无毒性作用;与天然海水相比,人工海水培育的罗氏沼虾幼体成活率为95.00%,蜕皮率为16.82%,并提高了幼体的特定生长率和食物转化率,降低了摄食率;幼体在天然海水中生长和脱壳所用能量[(18.83±1.35)%和(0.99±0.16)%]分别显著低于人工海水[(19.64±0.51)%和(1.47±0.06)%](P0.05);而在呼吸、排泄和排粪上的能量比例无显著性差异。研究表明,自制的人工海水对罗氏沼虾幼体的生长发育、蜕皮具有促进作用。     

The Effects of Water Velocity on the Growth,Dressout, and Body Composition of Channel Catfish,Ictalurus punctatus,Raised in Cicular Tanks

Research was conducted to determine the influence of water velocity on growth, dressout characteristics and fillet proximate composition of channel catfish, Ictalurus punctatus, raised in circular tanks. In this study, channel catfish cultured in water velocities of 4 cm/second averaged 75 g/fish higher weight gain and 0.12%/day greater specific growth rates than channel catfish cultured in tanks having no water velocity (P < 0.05). Channel catfish cultured at water velocities of 4 cm/second had significantly higher (P < 0.05) feed conversion efficiency and condition factor than channel catfish cultured in tanks having no water velocity. Channel catfish cultured at water velocities of 4 cm/second had significantly higher (P < 0.05) percentage carcass weight, fillet weight, and fillet moisture. The percentage visceral and fillet fat of channel catfish cultured at 4 cm/second was significantly lower (P < 0.05) than that for channel catfish raised in tanks having no water velocity. These results indicate that when cultured from initial weights of approximately 100 g to final weights exceeding 454 g in an environment having a water velocity of 4 cm/second, channel catfish have greater growth, dressout and lower fat levels than channel catfish produced in tanks having the identical water exchange rates but no water velocity.