延迟首次投喂对南方鲇(Silurus meridionalis Chen)仔鱼早期发育的影响

Effects of Delaying First Feeding on the Early Development of Southern Catfish(Silurus meridionalis) Larvae

将南方鲇仔鱼进行4种投喂处理(分别在出膜后4、5、6、7天进行首次投喂)和一个完全饥饿处理,出膜后第8天结束实验并测量干重、体长、头长、肛后长和头宽,计算肥满度(在22±0.5℃水温下进行)。结果显示,随着首次投喂时间的延迟,各处理组的干重、体长、头长、肛后长、头宽以及肥满度都呈现出逐渐降低的趋势;干重指标在出膜后6、7天首次投喂的2个处理组中表现为负增长;各投喂处理组的体长、头长、肛后长、头宽分别由17.03±0.15mm、3.20±0.05mm、9.63±0.12mm、3.06±0.05mm减小到12.00±0.11mm、2.28±0.03mm,6.76±0.10mm、2.60±0.05mm,各项指标的组间差异显著(P<0.05),且均较摄食前水平有所增长;将仔鱼肥满度(R)与延迟投喂天数(d)的关系拟合为:R=0.046 e-0.468d(n=15,r=0.788,P<0.001)。实验结果表明,南方鲇仔鱼早期发育过程中,由饥饿所引起的体重的负增长不会导致发育的停滞;但随着首次摄食的延迟,使仔鱼的发育速度明显降低。

The effects of four different first-feeding time （4, 5,6 and 7 days post-hatch, dph ）. Morphology characteristics of artificially fertilized larvae of southern catfish were conducted at 22.0 ± 0.5℃. The body length, head length, length behind anus, head width and body mass （ dry mass ） of larvae were measured and relative fatness was calculated at 8dph in both feeding and non-feeding groups. The results showed that the all measured and calculated parameters gradually decreased with the delay of first-feeding time. The body mass of larvae feeding at 6dph and 7dph were negative growth. The length, head length, length behind anus and head width of feeding groups significantly decreased from 17.03 ± 0.15 mm,3.20 ± 0.05mm, 9.63 ± 0.12mm,3.06 ± 0.05mm to 12.00 ± 0.11 mm,2.28 ± 0. 03 mm, 6.76 ± 0. 10mm,2.60 ±0.05mm, respectively （ P 〈 0.05 }. The morphology parameters showed a significant variation existing among experiment treatments （ P 〈 0.05 ）. The correlation between the relative fatness （R） and first-feeding time delayed （d） could be expressed as：R = 0.046e^-0.468d（n = 15 ,r =0.788,P 〈0. 001 ）. The lresuhs indicated that the negative growth of body mass did not prevent the development of southern catfish larvae. And the development of larvae was markedly impaired with the delay of first-feeding time.