温度诱导及药物处理对吉富罗非鱼雄性率及生长发育的影响

Effect of temperature and methyltestosterone on male rate,growth and development of GIFT Nile tilapia Oreochromis niloticus

以吉富罗非鱼GIFT Oreochromis niloticus同一个家系卵黄囊期鱼苗为研究对象,对比36℃水温诱导与浓度为0.6μg/g(饵料)甲基睾酮投喂对其雄性率及生长发育的影响。结果表明:36℃水温持续诱导10d的平均雄性率为(95.0±1.5)%,而30℃下投喂甲基睾酮10 d的平均雄性率仅为(73.0±2.4)%,投喂20 d后达到(96.0±1.3)%,36℃水温诱导+甲基睾酮投喂10 d的平均雄性率为(95.8±1.8)%,对照组仅为(56.0±2.1)%;后期的生长发育显示,36℃水温诱导+甲基睾酮投喂10 d组的生长速度最快,平均日增重达到了5.42 g/d,显著优于其他组(P<0.05);性腺组织切片观察显示,经过36℃水温诱导后的雌鱼大部分具有两性特征,无法正常排卵。研究表明,36℃水温诱导10 d能显著提高吉富罗非鱼仔鱼的雄性率,其效果已接近甲基睾酮处理20 d的效果,研究结果将有望应用于吉富罗非鱼苗种生产。

The effects of water temperature of 36 ℃ and diet containing 0. 6 μg/g methyltestosterone on male rate, growth and development of sibling prolarvae were studied in GIFT Nile tilapia Oreochromis niloticus. The results showed that the average male rate of （95. 0±1. 5）% was observed in the fish raised at 36℃ for 10 days. The average male rate of only （73. 0±2. 4）% was found in the fish fed the diet containing 0. 6 μg/g methyltestosterone at 30 ℃ for 10 days. However, the fish fed the diet containing 0. 6μg/g methyltestosterone for 20 days had male rate of up to （96. 0±1. 3）%. The fish fed the diet containing 0. 6 μg/g methyltestosterone at 36 ℃ water for 10 days had male rate of（95. 8±1. 8）%, about 40% higher than the fish in the control group （only 56%） did. The best growth （5. 42 g/d in average）was observed in the GIFT Nile tilapia fed the diet containing 0. 6 μg/g methyltestos-terone at 36 ℃ for 10 days, significantly higher than that the fish in the other groups （P〈0. 05）. Histologically, most females raised at 36 ℃ exhibited bisexuality without normal ovulation. In conclusion, the male rate is significantly improved, close to the fish fed the diet containing methyltestosterone at a dose of 0. 6μg/g feed for 20 days, in larval GIFT Nile tilapia reared at 36 ℃ for 10 days. The findings provide clues for the fingerling production of GIFT Nile tilapia.