刘变枝朱晓鸣韩 冬杨云霞金俊琰解绶启

(1.中国科学院水生生物研究所, 淡水生态与生物技术国家重点实验室, 武汉 430072; 2.河南农业大学牧医工程学院, 郑州 450002)

刘变枝1,2朱晓鸣1韩 冬1杨云霞1金俊琰1解绶启1

(1.中国科学院水生生物研究所, 淡水生态与生物技术国家重点实验室, 武汉 430072; 2.河南农业大学牧医工程学院, 郑州 450002)

以长吻仔鱼为实验对象, 探讨不同投喂水平对7—14日龄阶段和21—29日龄阶段的长吻仔稚鱼存活、生长以及鱼体组成的影响。7—14日龄阶段设计6个投喂水平, 分别为: 20、30、40、50、60和70 % IBW/d(IBW: initial body weight); 21—29日龄阶段设计6个投喂水平: 10、20、30、40、50、60 % IBW/d。实验结果表明: (1)投喂水平显著影响长吻仔稚鱼的存活和生长(P<0.05)。7—14日龄阶段, 投喂水平为30%—60% IBW/d处理组的仔鱼存活率显著高于20%与70 % IBW/d投喂组(P<0.05)。特定生长率随投喂水平的增加显著上升, 以60% IBW/d投喂组最高(P<0.05)。21—29日龄期间, 10% IBW/d投喂组存活率显著低于50% IBW/d投喂组(P<0.05), 特定生长率(SGR)则显著低于其他各处理组(P<0.05); (2)鱼体体长体重变异系数未受投喂水平的显著影响。鱼体产出与饲料投入之比、鱼体水分含量随投喂水平升高显著下降(P<0.05),粗蛋白含量则显著上升(P<0.05); 粗脂肪和粗灰分含量无显著差异; (3)分别通过存活率和投喂水平做一元二次回归、特定生长率与投喂水平做折线回归得到7—14日龄阶段的仔鱼最适投喂水平为43 % IBW/d; 通过仔鱼存活率和特定生长率与饲料投喂水平做折线回归得到21—29日龄阶段的仔鱼最适投喂水平分别为30.62% IBW/d和28.41% IBW/d。

长吻; 投喂水平; 仔稚鱼; 生长

投喂水平、水温和鱼体大小是影响鱼体生长最主要的三个因素[1]。鱼体的生长、饲料转化效率、营养物质的储积、鱼体的化学组成等均受到投喂水平的影响[2—7]。鱼类对营养物质的需求也受投喂水平的影响[8,9]。投饵不足危害鱼类的健康[6]或者减缓生长[5,10,11], 过量投喂则增加鱼体胃肠道的负担, 降低消化和吸收的效率[12], 从而降低饲料的利用率[5,6]。合适的投喂水平能够使得饲料的利用最大化, 减少饲料浪费, 降低水体污染和养殖成本。最适投喂水平因鱼规格的大小、水温、投喂策略和养殖条件的不同而不同[6,13,14]。相对于成鱼而言, 仔鱼一方面需要充足的食物来满足正常生长和发育, 另一方面更容易遭受投饵过度、或者投饵不足所造成的影响,从而影响苗种产出率。目前, 在长吻苗种培育中,长吻幼鱼体重、水温、投喂水平对其生长的影响本实验室已有所研究[15,16], 而关于长吻仔鱼最适投喂水平的研究尚未见报道。本文旨在研究投喂微颗粒饲料的情况下, 不同投喂水平对长吻仔鱼生长、存活以及鱼体组成的影响。

1 材料与方法

1.1 实验鱼和饲养条件

实验在室内循环水养殖系统内进行, 系统有27个圆形平底玻璃纤维缸组成(直径: 70 cm, 容积: 90 L)。实验缸底部出水口处包有一绢筛(孔径550 mm),用以防止仔鱼逃逸。因鱼类仔鱼阶段生长速度较快,短期内体重变化较大, 为方便管理以及保证以初始体重为表述的投喂水平结果的真实性, 我们对长吻仔鱼期最适投喂水平的需求进行分阶段实验: 实验用仔鱼于6日龄时由石首长吻良种场运回本所,一部分放入暂养缸内暂养(110 L水体, 作为二期实验用鱼)。一部分直接入实验缸进行一期实验(7—14 dph, days post hatching), 养殖密度为500尾/缸。同时随机取样20组鱼(每组10尾), 沥干水分称重, 用以计算初始平均体重 (约9.8 mg)。二期(21—29 dph)实验用鱼于20日龄时转入实验系统, 每缸放置200尾。同时随机取样150尾鱼, 沥干水分称重, 用以计算初始平均体重(约42 mg)。两期实验的投喂环境和投喂条件相同。

每期实验均设6个投喂水平(表1), 一期: 20、30、40、50、60、70% IBW/d; 二期: 10、20、30、40、50、60% IBW/d。每个处理4个重复。实验期间每天投喂三次(09: 00; 13: 00; 17: 00)。每次投喂量约为总投喂量的1/3。每次连续投喂1h, 用以减少微颗粒饲料在水中的营养流失, 同时保证仔鱼能够较好的摄食。1h后, 未被摄食的饲料、死鱼和粪便用虹吸管及时移出。

每期实验结束时, 计数每缸鱼数量, 整缸鱼沥干水分称重, 用于计算鱼体终末平均体重。同时, 每缸随机取样10尾, 滤纸吸干水分后, 单尾测量体重体长, 计算终末变异系数。取样后鱼样入−20℃冰箱保存, 用于体成分分析。

实验期间连续充气, 每天两次测定并记录水温、余氯和pH, 每周检测一次氨氮和溶氧含量。实验缸水流调整至(500 mL/min), 光亮周期为08: 00—21: 00, 氨氮≤0.5 mg/L, 水体溶氧≥5 mg/L, pH保持在7.0—7.2。

1.2 实验饲料

实验用饲料为武汉市高龙饲料有限公司生产的100#稚甲配合饲料粉料。饲料蛋白含量52.25%、脂肪含量为5.23%。将粉料加水, 用手揉搓成颗粒状,然后过筛分级, 制成粒径在40到60目之间(投喂7—14日龄阶段仔鱼)和40到30目之间(21—29日龄阶段仔鱼)的颗粒。放入−20℃冰箱中待用。实验饲料在水中的稳定性较好, 投喂后先在水面分散, 然后慢慢下沉, 有利于鱼苗充分摄食。

1.3 样品测定方法

样品用冷冻干燥机干燥, 然后在碾钵内充分研磨成粉状用于鱼体成分测定。实验鱼体样品的干物质、粗蛋白、粗脂肪、灰分的测定均参照AOAC(1984)的方法。干物质含量通过在105℃下烘烤至恒重测得。粗蛋白含量用凯氏定氮仪(2300 Kjeltec Analyzer Unit, FOSS TECATOR, Sweden)测定; 粗脂肪用氯仿-甲醇抽提法测得; 灰分在马福炉中550℃下充分灼烧测得。

1.4 统计方法

实验鱼的存活率(Survival)、特定生长率(Specific growth rate, SGR)、终末体重变异系数Coefficient of variation for final body wet weight, CVBWW)、终末体长变异系数(Coefficient of variation for final body length, CVBL)计算公式如下:

存活率(Survival, %)=100×终末存活/初始鱼数

特定生长率(SGR, %/d)=100×[(ln鱼体末重)−(ln鱼体初重)]/天数

终末体重变异系数(CVBWW)=标准差体重/平均值体重

终末体长变异系数(CVBL)=标准差体长/平均值体长

所有实验结果均采用Statistica 6.0软件进行分析。齐性检验(Homogeneity of variances)后做一元方差分析(One-way ANOVA), P<0.05为差异显著。若结果显著再进行邓肯多重比较(Duncan’s multiple range test)。

2 结果

2.1 存活、生长和鱼体组成

表1 实验设计和实验条件Tab.1 The experimental design and rearing conditions

7—14日龄阶段, 特定生长率随投喂水平增加显著上升, 以60% IBW/d投喂组最高(图1B, P< 0.05)。21—29日龄阶段, 特定生长率以10% IBW/d投喂组最低(图1B, P<0.05), 其他各处理组间随投喂水平增加而增加, 但无显著差异(P>0.05)。

在本实验中, 仔鱼鱼体分化未受投喂水平显著影响(表2, P<0.05)。各期仔鱼鱼体产出与饲料投入之比随投喂水平升高显著下降 (图2, P<0.05)。

鱼体水分、蛋白显著受投喂水平的影响(P<0.05),脂肪和灰分含量在各处理间无显著性差异(表3、表4, P>0.05)。7—14日龄阶段仔鱼(表3)鱼体水分含量随投喂水平增加而上升, 以70% IBW/d投喂组最高,显著高于20% IBW/d处理组(P<0.05)。粗蛋白含量以60%和70% IBW/d投喂组最高, 显著高于10%和20% IBW/d处理组(P<0.05)。21—29日龄阶段仔鱼(表4)投喂10% IBW/d投喂组仔鱼鱼体水分、粗蛋白含量均显著低于其他处理组(P<0.05)。

图1 不同投喂水平对长吻仔稚鱼存活率和特定生长率的影响(平均值±标准误)Fig.1 Survival rate and growth of Chinese longsnout catfish larvae at different feeding levels (mean±SE)

图2 单位饲料鱼体产出比值Fig.2 Ratio of weight gain and feed consumption in Chinese longsnout catfish larvae fed at different feeding levels (mean±SE)

2.2 最适投喂水平

7—14日龄阶段 将7—14日龄段仔稚鱼存活率和投喂水平做二次回归得到存活率与饲料投喂水平的关系为: y=−0.022x2+1.905x+21.96 (R2=0.766, n=6, P<0.05) 其中y表示为7—14日龄长吻仔稚鱼的存活率, x表示为饲料投喂水平。二者曲线关系(图3), 曲线最高处对应的饲料投喂水平为43.29% IBW/d, 表明满足7—14日龄仔鱼最大存活的饲料投喂水平为43.29% IBW/d。

将7—14日龄仔鱼各处理组的特定生长率与饲料投喂水平做折线回归(Broken-line regression), 得到特定生长率和饲料投喂水平之间的关系如下: 1.y= 0.09x+12.59 R2=0.932, n=5, P<0.05 (20

21—29日龄阶段 将21—29日龄仔鱼各处理组的存活率与饲料投喂水平做折线回归(Brokenline regression), 得到存活率和饲料投喂水平之间的关系如下: 1.y=0.462x+38.95 R2=0.993, n= 3, P<0.05 (10

表2 不同投喂水平对长吻仔鱼体长、体重分化的影响(平均值±标准误)Tab.2 The dispersion of growth and length in Chinese longsount catfish larvae at different feeding levels(Mean±SE)

表2 不同投喂水平对长吻仔鱼体长、体重分化的影响(平均值±标准误)Tab.2 The dispersion of growth and length in Chinese longsount catfish larvae at different feeding levels(Mean±SE)

注: 1.CVBWW终末体重变异系数Coefficient of variation of final body weight; 2.CVBL终末体长变异系数: Coefficient of variation of final body length

投喂水平Feeding level仔鱼日龄7—14 dph仔鱼日龄21—29 dph (% IBW/d) 终末体重变异系数1CVBWW投喂水平Feeding level (% IBW/d) 终末体重变异系数1CVBWW终末体长变异系数2CBL 20 0.21±0.02 10 0.41±0.03 0.13±0.01 30 0.10±0.06 20 0.43±0.05 0.15±0.01 40 0.20±0.03 30 0.39±0.06 0.11±0.02 50 0.18±0.04 40 0.32±0.04 0.11±0.01 60 0.27±0.04 50 0.40±0.04 0.14±0.01 70 0.41±0.26 60 0.35±0.04 0.11±0.01

表3 不同投喂水平对7—14日龄阶段长吻仔稚鱼体组成的影响(%湿重)(平均值±标准误)*Tab.3 Effects of feeding level on body composition in Chinese longsnout catfish larvae of 7—14dph fed with microdiet(% wet weight)(Mean±SE)

表3 不同投喂水平对7—14日龄阶段长吻仔稚鱼体组成的影响(%湿重)(平均值±标准误)*Tab.3 Effects of feeding level on body composition in Chinese longsnout catfish larvae of 7—14dph fed with microdiet(% wet weight)(Mean±SE)

注:*表中同列数值后不同的字母上标代表差异显著(n=4, P<0.05)Note: Means with different superscripts in the same column are significantly different (n=4, P<0.05)

7—14dph投喂水平Feeding level (% IBW/d) 水Moisture 粗蛋白Protein 粗脂肪Fatty 灰分Ash 20 91.69±0.27a5.54±0.16a1.63±0.07 0.82±0.08 30 91.54±0.40ab5.62±0.28a1.61±0.08 0.84±0.07 40 90.90±0.46ab6.30±0.09ab1.58±0.05 0.98±0.06 50 90.92±0.18ab6.03±0.11ab1.12±0.57 0.99±0.03 60 90.83±0.35ab6.02±0.23b1.68±0.07 1.01±0.06 70 90.52±0.24b6.45±0.22b1.82±0.09 0.92±0.06

表4 不同投喂水平对21—29日龄阶段长吻仔稚鱼体组成的影响(%湿重)(平均值±标准误)*Tab.4 Effects of feeding level on body composition in Chinese longsnout catfish larvae of 21—29dph (% wet weight) (mean±SE)

表4 不同投喂水平对21—29日龄阶段长吻仔稚鱼体组成的影响(%湿重)(平均值±标准误)*Tab.4 Effects of feeding level on body composition in Chinese longsnout catfish larvae of 21—29dph (% wet weight) (mean±SE)

注:*表中同列数值后不同的字母上标代表差异显著(n=4, P<0.05)Note: Means with different superscripts in the same column are significantly different (n=4, P<0.05)

投喂水平Feeding level (% IBW/d) 水分Moisture 粗蛋白Protein 粗脂肪Fatty 灰分Ash 21—29 dph 10 90.64±0.56a6.24±0.34a1.52±0.19 1.37±0.09 20 88.86±0.57b7.49±0.38b1.21±0.40 1.19±0.20 30 89.17±0.29b7.35±0.21b1.61±0.06 1.42±0.07 40 88.82±0.28b7.45±0.19b1.41±0.48 1.45±0.03 50 88.67±0.51b7.49±0.36b1.80±0.04 1.46±0.07 60 88.77±0.38b7.47±0.24b1.83±0.20 1.45±0.05

3 讨论

图3 投喂水平对7—14日龄长吻仔稚鱼存活率的影响Fig.3 Effect of feeding level on the survival rate of 7—14dph larvae

图4 投喂水平对7—14日龄段仔鱼特定生长率的影响Fig.4 Effect of feeding level on specific growth rate (SGR) of 7—14dph larvae

图5 投喂水平对21—29日龄段仔鱼存活率的影响Fig.5 Effect of feeding level on the survival rate of 21—29dph larvae

图6 投喂水平对21—29日龄段仔鱼特定生长率的影响Fig.6 Effect of feeding level on specific growth rate (SGR) of 21—29dph larvae

在本实验中, 随着饲料投喂水平的增加鱼体水分显著降低、粗蛋白含量显著升高。粗脂肪含量随着投喂水平的增加而上升, 但各处理组间无显著的差异。投喂水平对鱼体成分的影响在很多文献中已经报道[3,6,14,25—32]。投喂水平的升高导致鱼体水分降低、脂肪水平升高[3,6]。Ahmed[33]报道高投喂水平组囊鳃鲇的体蛋白含量显著高于低投喂水平组, 体脂肪含量随投喂水平增加直线上升, 水分含量则呈直线下降的趋势。Gatlin, et al.[34]报道鲶鱼稚鱼鱼体水分含量随投喂水平增加而下降。Storebakken 和Austreng[7]认为鱼体水分组成的变化与饲料投喂水平直接相关。在本实验中, 各日龄阶段仔鱼的体蛋白和体脂肪含量均随投喂水平增加而增加, 这种鱼体蛋白和脂肪随投喂水平增加而增加的趋势和在虹鳟[6]、革胡子鲇[29]中的研究结果一致。Rasmussen 和Ostenfeld[35]也证明脂肪在高投喂水平下快速生长的鱼体内更容易沉积。在低投喂水平下, 尽管鱼体能够储积较初始鱼体含量多的体蛋白, 鱼体脂肪沉积却处在较低的水平, 这也正说明脂肪是鱼体最先被动员的能量来源。这种在饵料不足的情况下, 脂肪最先被动员的现象在髙首鲟[5]、clariid catfish hybrid[30]、Clarias batrachus[36]的研究中得到了证实。有研究认为鱼体灰分含量随投喂水平的增加而降低[34], 在本实验中未观察到灰分与投喂水平之间的显著关系, 可能是由于本实验中样本量较少, 测定误差所致。

4 小结

结合本实验中存活率和特定生长率, 得出7—14日龄仔鱼每天最适投喂水平范围为: 43.1%—43.29%鱼体初始湿重; 21—29日龄仔鱼每天最适投喂水平分别为: 28.41%—30.62%鱼体初始湿重。

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EFFECTS OF FEEDING LEVEL ON GROWTH PERFORMANCE OF CHINESE LONGSNOUT CATFISH (LEIOCASSIS LONGIROSTRIS GÜNTHER) LARVAE

LIU Bian-Zhi1,2, ZHU Xiao-Ming1, HAN Dong1, YANG Yun-Xia1, JIN Jun-Yan1and XIE Shou-Qi1
(1.State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; 2.Henan Agricultural University, College of Animal Science and Veterinary Medicine, Zhengzhou 450002)

Chinese longsnout catfish, Leiocassis longirostris Günther is a high value aquaculture species in China.This study was carried out to investigate the optimal feeding level on the growth, survival, body composition, coefficient of variation of body wet weight and body length for Chinese longsnout catfish larvae of 7—14 dph and 21—29 dph, and for a need to determine the optimal feeding level in the commercial larviculture operations.Six feeding levels of 20, 30, 40, 50, 60 and 70% initial body weight (IBW)/d for 7—14 dph larvae, and 10, 20, 30, 40, 50 and 60% IBW/d for 21—29 dph larvae were adopted, respectively.The results showed that growth performance and survival rate was significantly higher in 7—14 dph larvae fed at the feeding levels of 30%—60% IBW/d than 20% and 70% IBW/d (P<0.05).Specific growth rate (SGR) increased with the increasing feeding levels and reached the highest level at the 60% IBW/d group (P<0.05).For 21—29 dph larvae, the survival rate and SGR were significantly lower in the 10% IBW/d group than in the 50% IBW/d group (P<0.05).In both trials, differentiations of body wet weight and body length in larvae were not affected by the feeding level (P>0.05).Body crude fat and ash content were also not affected by the different feeding level.Ratio of weight gain to feed consumption and body moisture contents in larvae significantly decreased while body protein contents increased with the increasing feeding levels (P<0.05).Based on quadratic linear regression analysis of survival rate and broken line analysis of SGR in relation to the feeding level, the optimal feeding level for 7—14 dph larvae was 43% IBW/d.Based on the broken line analysis between the survival rate or specific growth rate and the feeding level, the optimal feeding levels for 21—29 dph larvae were 30.62% IBW/d and 28.41% IBW/d, respectively.

Leiocassis longirostris Günther; Feeding level; Larvae; Growth performance

S965

A

1000-3207(2013)02-0261-08

10.7541/2013.13

2011-12-05;

2012-10-31

现代农业产业技术体系建设专项资金(CARS-46-19); 公益性行业(农业)专项“水产养殖动物营养需求与高效配合饲料开发(201003020)资助

刘变枝(1981－), 女, 河南开封人; 博士研究生; 研究方向为鱼类生理生态学。E-mail: liubianzhi@126.com

解绶启, E-mail: sqxie@ihb.ac.cn