投喂水平對長吻仔稚魚生長和存活的影響

劉變枝朱曉鳴韓 冬楊云霞金俊琰解綬啟

(1.中國科學院水生生物研究所, 淡水生態與生物技術國家重點實驗室, 武漢 430072; 2.河南農業大學牧醫工程學院, 鄭州 450002)

劉變枝1,2朱曉鳴1韓 冬1楊云霞1金俊琰1解綬啟1

(1.中國科學院水生生物研究所, 淡水生態與生物技術國家重點實驗室, 武漢 430072; 2.河南農業大學牧醫工程學院, 鄭州 450002)

以長吻仔魚為實驗對象, 探討不同投喂水平對7—14日齡階段和21—29日齡階段的長吻仔稚魚存活、生長以及魚體組成的影響。7—14日齡階段設計6個投喂水平, 分別為: 20、30、40、50、60和70 % IBW/d(IBW: initial body weight); 21—29日齡階段設計6個投喂水平: 10、20、30、40、50、60 % IBW/d。實驗結果表明: (1)投喂水平顯著影響長吻仔稚魚的存活和生長(P<0.05)。7—14日齡階段, 投喂水平為30%—60% IBW/d處理組的仔魚存活率顯著高于20%與70 % IBW/d投喂組(P<0.05)。特定生長率隨投喂水平的增加顯著上升, 以60% IBW/d投喂組最高(P<0.05)。21—29日齡期間, 10% IBW/d投喂組存活率顯著低于50% IBW/d投喂組(P<0.05), 特定生長率(SGR)則顯著低于其他各處理組(P<0.05); (2)魚體體長體重變異系數未受投喂水平的顯著影響。魚體產出與飼料投入之比、魚體水分含量隨投喂水平升高顯著下降(P<0.05),粗蛋白含量則顯著上升(P<0.05); 粗脂肪和粗灰分含量無顯著差異; (3)分別通過存活率和投喂水平做一元二次回歸、特定生長率與投喂水平做折線回歸得到7—14日齡階段的仔魚最適投喂水平為43 % IBW/d; 通過仔魚存活率和特定生長率與飼料投喂水平做折線回歸得到21—29日齡階段的仔魚最適投喂水平分別為30.62% IBW/d和28.41% IBW/d。

長吻; 投喂水平; 仔稚魚; 生長

投喂水平、水溫和魚體大小是影響魚體生長最主要的三個因素[1]。魚體的生長、飼料轉化效率、營養物質的儲積、魚體的化學組成等均受到投喂水平的影響[2—7]。魚類對營養物質的需求也受投喂水平的影響[8,9]。投餌不足危害魚類的健康[6]或者減緩生長[5,10,11], 過量投喂則增加魚體胃腸道的負擔, 降低消化和吸收的效率[12], 從而降低飼料的利用率[5,6]。合適的投喂水平能夠使得飼料的利用最大化, 減少飼料浪費, 降低水體污染和養殖成本。最適投喂水平因魚規格的大小、水溫、投喂策略和養殖條件的不同而不同[6,13,14]。相對于成魚而言, 仔魚一方面需要充足的食物來滿足正常生長和發育, 另一方面更容易遭受投餌過度、或者投餌不足所造成的影響,從而影響苗種產出率。目前, 在長吻苗種培育中,長吻幼魚體重、水溫、投喂水平對其生長的影響本實驗室已有所研究[15,16], 而關于長吻仔魚最適投喂水平的研究尚未見報道。本文旨在研究投喂微顆粒飼料的情況下, 不同投喂水平對長吻仔魚生長、存活以及魚體組成的影響。

1 材料與方法

1.1 實驗魚和飼養條件

實驗在室內循環水養殖系統內進行, 系統有27個圓形平底玻璃纖維缸組成(直徑: 70 cm, 容積: 90 L)。實驗缸底部出水口處包有一絹篩(孔徑550 mm),用以防止仔魚逃逸。因魚類仔魚階段生長速度較快,短期內體重變化較大, 為方便管理以及保證以初始體重為表述的投喂水平結果的真實性, 我們對長吻仔魚期最適投喂水平的需求進行分階段實驗: 實驗用仔魚于6日齡時由石首長吻良種場運回本所,一部分放入暫養缸內暫養(110 L水體, 作為二期實驗用魚)。一部分直接入實驗缸進行一期實驗(7—14 dph, days post hatching), 養殖密度為500尾/缸。同時隨機取樣20組魚(每組10尾), 瀝干水分稱重, 用以計算初始平均體重 (約9.8 mg)。二期(21—29 dph)實驗用魚于20日齡時轉入實驗系統, 每缸放置200尾。同時隨機取樣150尾魚, 瀝干水分稱重, 用以計算初始平均體重(約42 mg)。兩期實驗的投喂環境和投喂條件相同。

每期實驗均設6個投喂水平(表1), 一期: 20、30、40、50、60、70% IBW/d; 二期: 10、20、30、40、50、60% IBW/d。每個處理4個重復。實驗期間每天投喂三次(09: 00; 13: 00; 17: 00)。每次投喂量約為總投喂量的1/3。每次連續投喂1h, 用以減少微顆粒飼料在水中的營養流失, 同時保證仔魚能夠較好的攝食。1h后, 未被攝食的飼料、死魚和糞便用虹吸管及時移出。

每期實驗結束時, 計數每缸魚數量, 整缸魚瀝干水分稱重, 用于計算魚體終末平均體重。同時, 每缸隨機取樣10尾, 濾紙吸干水分后, 單尾測量體重體長, 計算終末變異系數。取樣后魚樣入?20℃冰箱保存, 用于體成分分析。

實驗期間連續充氣, 每天兩次測定并記錄水溫、余氯和pH, 每周檢測一次氨氮和溶氧含量。實驗缸水流調整至(500 mL/min), 光亮周期為08: 00—21: 00, 氨氮≤0.5 mg/L, 水體溶氧≥5 mg/L, pH保持在7.0—7.2。

1.2 實驗飼料

實驗用飼料為武漢市高龍飼料有限公司生產的100#稚甲配合飼料粉料。飼料蛋白含量52.25%、脂肪含量為5.23%。將粉料加水, 用手揉搓成顆粒狀,然后過篩分級, 制成粒徑在40到60目之間(投喂7—14日齡階段仔魚)和40到30目之間(21—29日齡階段仔魚)的顆粒。放入?20℃冰箱中待用。實驗飼料在水中的穩定性較好, 投喂后先在水面分散, 然后慢慢下沉, 有利于魚苗充分攝食。

1.3 樣品測定方法

樣品用冷凍干燥機干燥, 然后在碾缽內充分研磨成粉狀用于魚體成分測定。實驗魚體樣品的干物質、粗蛋白、粗脂肪、灰分的測定均參照AOAC(1984)的方法。干物質含量通過在105℃下烘烤至恒重測得。粗蛋白含量用凱氏定氮儀(2300 Kjeltec Analyzer Unit, FOSS TECATOR, Sweden)測定; 粗脂肪用氯仿-甲醇抽提法測得; 灰分在馬福爐中550℃下充分灼燒測得。

1.4 統計方法

實驗魚的存活率(Survival)、特定生長率(Specific growth rate, SGR)、終末體重變異系數Coefficient of variation for final body wet weight, CVBWW)、終末體長變異系數(Coefficient of variation for final body length, CVBL)計算公式如下:

存活率(Survival, %)=100×終末存活/初始魚數

特定生長率(SGR, %/d)=100×[(ln魚體末重)?(ln魚體初重)]/天數

終末體重變異系數(CVBWW)=標準差體重/平均值體重

終末體長變異系數(CVBL)=標準差體長/平均值體長

所有實驗結果均采用Statistica 6.0軟件進行分析。齊性檢驗(Homogeneity of variances)后做一元方差分析(One-way ANOVA), P<0.05為差異顯著。若結果顯著再進行鄧肯多重比較(Duncan’s multiple range test)。

2 結果

2.1 存活、生長和魚體組成

表1 實驗設計和實驗條件Tab.1 The experimental design and rearing conditions

7—14日齡階段, 特定生長率隨投喂水平增加顯著上升, 以60% IBW/d投喂組最高(圖1B, P< 0.05)。21—29日齡階段, 特定生長率以10% IBW/d投喂組最低(圖1B, P<0.05), 其他各處理組間隨投喂水平增加而增加, 但無顯著差異(P>0.05)。

在本實驗中, 仔魚魚體分化未受投喂水平顯著影響(表2, P<0.05)。各期仔魚魚體產出與飼料投入之比隨投喂水平升高顯著下降 (圖2, P<0.05)。

魚體水分、蛋白顯著受投喂水平的影響(P<0.05),脂肪和灰分含量在各處理間無顯著性差異(表3、表4, P>0.05)。7—14日齡階段仔魚(表3)魚體水分含量隨投喂水平增加而上升, 以70% IBW/d投喂組最高,顯著高于20% IBW/d處理組(P<0.05)。粗蛋白含量以60%和70% IBW/d投喂組最高, 顯著高于10%和20% IBW/d處理組(P<0.05)。21—29日齡階段仔魚(表4)投喂10% IBW/d投喂組仔魚魚體水分、粗蛋白含量均顯著低于其他處理組(P<0.05)。

圖1 不同投喂水平對長吻仔稚魚存活率和特定生長率的影響(平均值±標準誤)Fig.1 Survival rate and growth of Chinese longsnout catfish larvae at different feeding levels (mean±SE)

圖2 單位飼料魚體產出比值Fig.2 Ratio of weight gain and feed consumption in Chinese longsnout catfish larvae fed at different feeding levels (mean±SE)

2.2 最適投喂水平

7—14日齡階段 將7—14日齡段仔稚魚存活率和投喂水平做二次回歸得到存活率與飼料投喂水平的關系為: y=?0.022x2+1.905x+21.96 (R2=0.766, n=6, P<0.05) 其中y表示為7—14日齡長吻仔稚魚的存活率, x表示為飼料投喂水平。二者曲線關系(圖3), 曲線最高處對應的飼料投喂水平為43.29% IBW/d, 表明滿足7—14日齡仔魚最大存活的飼料投喂水平為43.29% IBW/d。

將7—14日齡仔魚各處理組的特定生長率與飼料投喂水平做折線回歸(Broken-line regression), 得到特定生長率和飼料投喂水平之間的關系如下: 1.y= 0.09x+12.59 R2=0.932, n=5, P<0.05 (20

21—29日齡階段 將21—29日齡仔魚各處理組的存活率與飼料投喂水平做折線回歸(Brokenline regression), 得到存活率和飼料投喂水平之間的關系如下: 1.y=0.462x+38.95 R2=0.993, n= 3, P<0.05 (10

表2 不同投喂水平對長吻仔魚體長、體重分化的影響(平均值±標準誤)Tab.2 The dispersion of growth and length in Chinese longsount catfish larvae at different feeding levels(Mean±SE)

表2 不同投喂水平對長吻仔魚體長、體重分化的影響(平均值±標準誤)Tab.2 The dispersion of growth and length in Chinese longsount catfish larvae at different feeding levels(Mean±SE)

注: 1.CVBWW終末體重變異系數Coefficient of variation of final body weight; 2.CVBL終末體長變異系數: Coefficient of variation of final body length

投喂水平Feeding level仔魚日齡7—14 dph仔魚日齡21—29 dph (% IBW/d) 終末體重變異系數1CVBWW投喂水平Feeding level (% IBW/d) 終末體重變異系數1CVBWW終末體長變異系數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 不同投喂水平對7—14日齡階段長吻仔稚魚體組成的影響(%濕重)(平均值±標準誤)*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 不同投喂水平對7—14日齡階段長吻仔稚魚體組成的影響(%濕重)(平均值±標準誤)*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:*表中同列數值后不同的字母上標代表差異顯著(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 不同投喂水平對21—29日齡階段長吻仔稚魚體組成的影響(%濕重)(平均值±標準誤)*Tab.4 Effects of feeding level on body composition in Chinese longsnout catfish larvae of 21—29dph (% wet weight) (mean±SE)

表4 不同投喂水平對21—29日齡階段長吻仔稚魚體組成的影響(%濕重)(平均值±標準誤)*Tab.4 Effects of feeding level on body composition in Chinese longsnout catfish larvae of 21—29dph (% wet weight) (mean±SE)

注:*表中同列數值后不同的字母上標代表差異顯著(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 討論

圖3 投喂水平對7—14日齡長吻仔稚魚存活率的影響Fig.3 Effect of feeding level on the survival rate of 7—14dph larvae

圖4 投喂水平對7—14日齡段仔魚特定生長率的影響Fig.4 Effect of feeding level on specific growth rate (SGR) of 7—14dph larvae

圖5 投喂水平對21—29日齡段仔魚存活率的影響Fig.5 Effect of feeding level on the survival rate of 21—29dph larvae

圖6 投喂水平對21—29日齡段仔魚特定生長率的影響Fig.6 Effect of feeding level on specific growth rate (SGR) of 21—29dph larvae

在本實驗中, 隨著飼料投喂水平的增加魚體水分顯著降低、粗蛋白含量顯著升高。粗脂肪含量隨著投喂水平的增加而上升, 但各處理組間無顯著的差異。投喂水平對魚體成分的影響在很多文獻中已經報道[3,6,14,25—32]。投喂水平的升高導致魚體水分降低、脂肪水平升高[3,6]。Ahmed[33]報道高投喂水平組囊鰓鲇的體蛋白含量顯著高于低投喂水平組, 體脂肪含量隨投喂水平增加直線上升, 水分含量則呈直線下降的趨勢。Gatlin, et al.[34]報道鯰魚稚魚魚體水分含量隨投喂水平增加而下降。Storebakken 和Austreng[7]認為魚體水分組成的變化與飼料投喂水平直接相關。在本實驗中, 各日齡階段仔魚的體蛋白和體脂肪含量均隨投喂水平增加而增加, 這種魚體蛋白和脂肪隨投喂水平增加而增加的趨勢和在虹鱒[6]、革胡子鲇[29]中的研究結果一致。Rasmussen 和Ostenfeld[35]也證明脂肪在高投喂水平下快速生長的魚體內更容易沉積。在低投喂水平下, 盡管魚體能夠儲積較初始魚體含量多的體蛋白, 魚體脂肪沉積卻處在較低的水平, 這也正說明脂肪是魚體最先被動員的能量來源。這種在餌料不足的情況下, 脂肪最先被動員的現象在髙首鱘[5]、clariid catfish hybrid[30]、Clarias batrachus[36]的研究中得到了證實。有研究認為魚體灰分含量隨投喂水平的增加而降低[34], 在本實驗中未觀察到灰分與投喂水平之間的顯著關系, 可能是由于本實驗中樣本量較少, 測定誤差所致。

4 小結

結合本實驗中存活率和特定生長率, 得出7—14日齡仔魚每天最適投喂水平范圍為: 43.1%—43.29%魚體初始濕重; 21—29日齡仔魚每天最適投喂水平分別為: 28.41%—30.62%魚體初始濕重。

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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

現代農業產業技術體系建設專項資金(CARS-46-19); 公益性行業(農業)專項“水產養殖動物營養需求與高效配合飼料開發(201003020)資助

劉變枝(1981－), 女, 河南開封人; 博士研究生; 研究方向為魚類生理生態學。E-mail: liubianzhi@126.com

解綬啟, E-mail: sqxie@ihb.ac.cn