劉 偉,文 華,蔣 明,吳 凡,田 娟,楊長庚
(農(nóng)業(yè)部淡水生物多樣性保護(hù)與利用重點(diǎn)開放實(shí)驗(yàn)室,中國水產(chǎn)科學(xué)研究院 長江水產(chǎn)研究所,湖北 武漢 430223)
吉富羅非魚成魚對(duì)8種常見植物源飼料原料的表觀消化率
劉 偉,文 華,蔣 明,吳 凡,田 娟,楊長庚
(農(nóng)業(yè)部淡水生物多樣性保護(hù)與利用重點(diǎn)開放實(shí)驗(yàn)室,中國水產(chǎn)科學(xué)研究院 長江水產(chǎn)研究所,湖北 武漢 430223)
【目的】 研究吉富羅非魚成魚對(duì)8種植物源飼料原料中營養(yǎng)成分和總能的表觀消化率(ADC),為吉富羅非魚飼料的配制提供科學(xué)依據(jù)?!痉椒ā?選擇6種植物源蛋白原料(全脂膨化大豆、豆粕、棉粕、菜粕、花生粕、玉米蛋白粉)和2種能量原料(小麥麩、面粉),分別與基礎(chǔ)飼料按照3∶7的質(zhì)量比配制成試驗(yàn)飼料,投喂體質(zhì)量為(290.6±5.8) g/尾的吉富羅非魚成魚,1周后,采用網(wǎng)撈法收集成型完整的糞便,研究吉富羅非魚成魚對(duì)8種原料的粗蛋白、粗脂肪、總能、總磷和氨基酸的ADC?!窘Y(jié)果】 吉富羅非魚成魚對(duì)8種原料粗脂肪的ADC差異不顯著(P>0.05),均高于89.42%;對(duì)8種原料粗蛋白、總能的ADC和氨基酸的平均ADC均以面粉最高,小麥麩最低;各原料氨基酸的平均ADC變化趨勢與蛋白質(zhì)的ADC趨勢一致。在6種蛋白質(zhì)原料中,吉富羅非魚成魚對(duì)其粗蛋白、氨基酸平均、總能和總磷的ADC分別為85.70%~94.41%,89.07%~95.87%,62.92%~94.64%和32.96%~83.39%;其中,對(duì)全脂膨化大豆、豆粕、棉粕、花生粕和玉米蛋白粉粗蛋白的ADC均高于89%,且這5種原料間無顯著差異(P>0.05);對(duì)花生粕、玉米蛋白粉和全脂膨化大豆總能的ADC顯著高于菜粕和棉粕(P<0.05),而與豆粕無顯著差異(P>0.05);對(duì)玉米蛋白粉總磷的ADC顯著高于其他原料(P<0.05)?!窘Y(jié)論】 玉米蛋白粉、花生粕、全脂膨化大豆、豆粕可作為吉富羅非魚成魚飼料中優(yōu)質(zhì)的蛋白源,面粉則是吉富羅非魚成魚飼料中優(yōu)質(zhì)的能量源。
吉富羅非魚成魚;植物原料;表觀消化率
消化率是動(dòng)物從原料中消化吸收的養(yǎng)分占總攝入養(yǎng)分的百分比,是評(píng)價(jià)飼料營養(yǎng)價(jià)值的重要指標(biāo)之一[1]。了解飼料原料中各種營養(yǎng)素的消化率是配制平衡飼料的前提,對(duì)原料間的相互替代也具有重要的指導(dǎo)意義[2]。羅非魚是聯(lián)合國糧農(nóng)組織向全世界推薦的優(yōu)質(zhì)魚類,也是我國主導(dǎo)水產(chǎn)養(yǎng)殖品種之一。自2006年來,我國羅非魚的養(yǎng)殖產(chǎn)量一直穩(wěn)定在100萬t以上,穩(wěn)居世界羅非魚養(yǎng)殖產(chǎn)量首位。
多年來,一直持續(xù)有羅非魚對(duì)各種飼料原料表觀消化率(Apparent digestibility coefficients,ADC)的研究報(bào)道[2-17]發(fā)表,但這些報(bào)道的研究對(duì)象主要為較小規(guī)格體質(zhì)量(體質(zhì)量<100 g/尾)的尼羅羅非魚,而對(duì)于大規(guī)格(體質(zhì)量>200 g/尾)羅非魚的報(bào)道不多,而且現(xiàn)有研究均未涉及到各原料氨基酸、總磷等的ADC。另外,大規(guī)格的羅非魚(>200 g/尾)對(duì)我國常見的植物飼料原料,如花生粕、玉米蛋白粉、面粉等的ADC亦尚未見報(bào)道。
吉富品系尼羅羅非魚(吉富羅非魚)具有生長快、產(chǎn)量高、耐低氧、遺傳性狀穩(wěn)定等優(yōu)點(diǎn),是現(xiàn)今我國主要養(yǎng)殖的羅非魚品系之一。目前,僅見吉富羅非魚幼魚(7.05 g/尾)對(duì)飼料原料ADC的報(bào)道[17]。本研究選擇8種國內(nèi)飼料生產(chǎn)中經(jīng)常使用的植物性原料,以吉富羅非魚成魚(>290 g/尾)為研究對(duì)象,測定其對(duì)原料中的粗蛋白、粗脂肪、總能、總磷和氨基酸等的ADC,旨在為開發(fā)吉富羅非魚精準(zhǔn)的配合飼料提供科學(xué)依據(jù)。
1.1 原料及試驗(yàn)飼料
8種試驗(yàn)原料包括6種蛋白原料(全脂膨化大豆、豆粕、棉粕、菜粕、花生粕、玉米蛋白粉)和2種能量原料(小麥麩、面粉),購自青島七好生物科技有限公司,其營養(yǎng)成分含量見表1。因小麥麩和面粉中的蛋白含量相對(duì)較低,為減少基礎(chǔ)飼料對(duì)試驗(yàn)結(jié)果的影響,本試驗(yàn)分別設(shè)計(jì)了用于測定蛋白原料ADC的基礎(chǔ)飼料1和用于測定能量原料ADC的基礎(chǔ)飼料2,其具體配方見表2。所有原料粉碎細(xì)度達(dá)到0.25 mm。在基礎(chǔ)飼料中添加0.1%三氧化二釔(Y2O3)作為標(biāo)記物,采用逐級(jí)擴(kuò)散法,均勻混合到基礎(chǔ)飼料粉料中。取70%添加標(biāo)記物的基礎(chǔ)飼料和30%的待測原料,充分混合均勻后,添加20%左右的水,再次混勻,用絞肉機(jī)制成直徑3 mm的顆粒飼料。風(fēng)干置于-20 ℃冰箱中備用。共計(jì)制作10種試驗(yàn)飼料,分別為2種基礎(chǔ)飼料和8種含30%待測原料的飼料。
1.2 試驗(yàn)魚與養(yǎng)殖條件
試驗(yàn)魚來源于廣西南寧國家級(jí)羅非魚良種場。運(yùn)回后,暫養(yǎng)在循環(huán)水養(yǎng)殖系統(tǒng)中,先用商品料喂養(yǎng),以恢復(fù)羅非魚體質(zhì),并使其適應(yīng)養(yǎng)殖環(huán)境。3周后,選擇規(guī)格整齊,表觀健康的羅非魚,隨機(jī)分養(yǎng)于30個(gè)養(yǎng)殖桶中(有效容積450 L/桶),每桶放魚15尾。試驗(yàn)魚的平均體質(zhì)量(290.6±5.8) g/尾。分桶后,先用基礎(chǔ)飼料2投喂,每天表觀飽食投喂2次(09:00,16:30), 1周后投喂試驗(yàn)飼料,每種飼料隨機(jī)投喂3個(gè)養(yǎng)殖桶,每天表觀飽食投喂2次(09:00,16:30)。喂養(yǎng)1周后,開始收集糞便,共收集10 d。試驗(yàn)期間,采用自然光照,水流約2 L/min,水溫(30.1±0.6) ℃,水中溶解氧>4 mg/L、氨態(tài)氮<0.2 mg/L、pH為7.5~8.3。
表1 8種飼料原料營養(yǎng)成分含量(以干物質(zhì)計(jì))Table 1 Nutrient compositions and contents of amino acids of test ingredients
注:除總能外,其余指標(biāo)含量用質(zhì)量分?jǐn)?shù)表示。表2同。
Note:All indexes are mass fraction except gross energy.The same for Table 2.
表2 基礎(chǔ)飼料配方及營養(yǎng)組成Table 2 Ingredients and nutrients of the reference diets
注:維生素和礦物質(zhì)預(yù)混料根據(jù)文獻(xiàn)[10]配制。
Note:Vitamin and mineral premix are based on literature [10].
1.3 糞便收集
每天下午投喂0.5 h后,虹吸出養(yǎng)殖桶中多余的飼料以及排泄的糞便。于每晚20:00-21:00羅非魚排便高峰期,用密網(wǎng)撈取并挑選條狀成型、飽滿的糞便,每桶收集的糞便單獨(dú)放入對(duì)應(yīng)的培養(yǎng)皿中,隨后在-40 ℃的冰箱中冷凍。于真空冷凍干燥機(jī)中干燥糞便,冷凍干燥72 h。取出,粉碎過0.25 mm篩,放入樣品袋中,于-40 ℃的冰箱中保存?zhèn)溆谩?/p>
1.4 樣品分析測定方法
飼料和糞便中的粗蛋白采用凱氏定氮法(GB/T 5009.3)測定,粗脂肪采用索氏抽提法(GB/T 5009.6) 測定,粗灰分采用灼燒稱重法(GB/T 5009.4) 測定,總磷采用鉬黃分光光度比色法(GB/T 5009.87) 測定,Y2O3的含量采用電感耦合等離子質(zhì)譜法(GB/T 18115.1)測定??偰懿捎醚鯊棞y熱儀(Parr-6200) 直接測定,氨基酸的含量通過氨基酸分析儀(日立L-8900)直接測定。
1.5 數(shù)據(jù)處理
10種試驗(yàn)飼料中粗蛋白、粗脂肪、氨基酸、總磷等營養(yǎng)成分和能量的表觀消化率按式(1)計(jì)算:
ADCd=[1-(Nf/Nd)×(Md/Mf)]×100%。
(1)
式中:ADCd為飼料營養(yǎng)成分或能量的表觀消化率(%),Md為飼料中Y2O3的含量(質(zhì)量分?jǐn)?shù),%),Mf為糞便中Y2O3的含量(質(zhì)量分?jǐn)?shù),%),Nd為飼料中營養(yǎng)成分的含量(質(zhì)量分?jǐn)?shù),%)或能量含量(kJ/g),Nf為糞便中營養(yǎng)成分的含量(質(zhì)量分?jǐn)?shù),%)或能量含量(kJ/g)。
對(duì)8種試驗(yàn)原料的表觀消化率按式(2)計(jì)算:
ADCi=ADCt+[(ADCt-ADCr)×
(0.7×Nr)/(0.3×Ni)]。
(2)
式中:ADCi為試驗(yàn)原料的表觀消化率(%);ADCt為含30%待測原料的試驗(yàn)飼料的營養(yǎng)成分或能量表觀消化率(%),根據(jù)式(1)計(jì)算;ADCr為基礎(chǔ)飼料的營養(yǎng)成分或能量的表觀消化率(%),根據(jù)式(1)計(jì)算;Nr為基礎(chǔ)飼料中營養(yǎng)成分的含量(質(zhì)量分?jǐn)?shù),%)或能量含量(kJ/g);Ni為試驗(yàn)原料中營養(yǎng)成分的含量(質(zhì)量分?jǐn)?shù),%)或能量含量(kJ/g)。
2.1 吉富羅非魚成魚對(duì)粗蛋白、粗脂肪、總磷和總能的表觀消化率
吉富羅非魚成魚對(duì)8種飼料原料粗蛋白、粗脂肪、總磷和總能的ADC見表3。由表3可知,在6種蛋白原料中,試驗(yàn)魚對(duì)各原料粗蛋白的ADC在85.70%~94.41%,其中對(duì)花生粕、棉粕和玉米蛋白粉粗蛋白的ADC顯著高于菜粕(P<0.05);對(duì)各原料粗脂肪的ADC均在89%以上,且各原料間不存在顯著性差異(P>0.05);對(duì)總磷的ADC在32.96%~83.39%,其中對(duì)全脂膨化大豆、豆粕和花生粕總磷的ADC在40%以下,顯著低于其他原料(P<0.05),而對(duì)玉米蛋白粉總磷的ADC(83.39%)則顯著高于其他原料(P<0.05);對(duì)總能的ADC在62.92%~94.64%,其中對(duì)全脂膨化大豆、花生粕和玉米蛋白粉總能的ADC顯著高于棉粕和菜粕(P<0.05)。
表3 吉富羅非魚成魚對(duì)8種飼料原料粗蛋白、粗脂肪、總磷和總能的表觀消化率(n=3)Table 3 Apparent digestibility coefficients of crude protein,crude lipid,total phosphrus and gross energy in eight tested ingredients for adult Oreochromis niloticus (n=3) %
注:-表示計(jì)算結(jié)果遠(yuǎn)大于100%;同列數(shù)據(jù)后標(biāo)不同小寫字母表示差異顯著(P<0.05)。下表同。
Note:- indicates greater than 100%.Values in each row with different lowercase letters indicate significant difference (P<0.05).The same as following table.
在2種能量原料中,試驗(yàn)魚對(duì)面粉總能和粗蛋白的ADC均顯著高于小麥麩(P<0.05),對(duì)小麥麩總能的ADC僅為39.91%,而面粉的則高達(dá)103.50%;對(duì)小麥麩和面粉粗蛋白的ADC分別為76.27%和101.12%;對(duì)面粉和小麥麩粗脂肪的ADC差異不顯著(P>0.05)。
2.2 吉富羅非魚成魚對(duì)氨基酸的表觀消化率
吉富羅非魚成魚對(duì)8種飼料原料氨基酸的ADC見表4。
表4 吉富羅非魚成魚對(duì)8種飼料原料氨基酸的表觀消化率(n=3)Table 4 Apparent digestibility coefficients of amino acids in eight tested ingredients for adult Oreochromis niloticus (n=3) %
注:NEAA.非必需氨基酸;EAA.必需氨基酸;TAA.總氨基酸。
Note:NEAA.Non-essential amino acids;EAA.Essential amino acids;TAA.Total amino acids.
由表4可知,在6種蛋白原料中,試驗(yàn)魚對(duì)各原料非必需氨基酸的平均ADC差異不顯著(P>0.05),在89.76%~96.54%;對(duì)各原料必需氨基酸的平均ADC為88.47%~95.17%,其中對(duì)菜粕必需氨基酸的平均ADC顯著低于豆粕、棉粕和玉米蛋白粉(P<0.05),其余各原料間差異不顯著(P>0.05);對(duì)各原料總氨基酸的平均ADC以菜粕最低(89.07%),與全脂膨化大豆差異不顯著(P>0.05),但顯著低于其他原料(P<0.05)。試驗(yàn)魚對(duì)纈氨酸(Val)、異亮氨酸(Ile)、賴氨酸(Lys)、組氨酸(His)和精氨酸(Arg)的ADC差異均不顯著(P>0.05);對(duì)全脂膨化大豆中的半胱氨酸(Cys)、苯丙氨酸(Phe)、酪氨酸(Tyr)和谷氨酸(Glu)的ADC顯著小于豆粕(P<0.05),對(duì)二者其他氨基酸的ADC差異不顯著(P>0.05);對(duì)玉米蛋白粉各氨基酸的ADC均大于92%;對(duì)棉粕半胱氨酸(Cys)的ADC為87.54%,其余均大于92%;對(duì)菜粕氨基酸的ADC在83.55%~98.27%,且大部分在90%以下;對(duì)花生粕中甘氨酸(Gly)的ADC為87.34%,其余均大于90%。
試驗(yàn)魚對(duì)小麥麩的非必需氨基酸、必需氨基酸和總氨基酸的平均ADC均顯著低于其他7種原料(P<0.05),對(duì)面粉的必需氨基酸和總氨基酸的平均ADC顯著高于其他7種原料(P<0.05)。面粉的氨基酸表觀消化率較高,大多超過100%。
3.1 影響消化率測定準(zhǔn)確性的因素
本試驗(yàn)參考Cho等[18]的方法用被測飼料原料取代一部分基礎(chǔ)飼料配制成試驗(yàn)飼料,取代比例為30%,同時(shí)根據(jù)飼料原料蛋白含量的高低,配制2種基礎(chǔ)飼料,這樣可保證營養(yǎng)物質(zhì)的均衡,有利于魚體的消化吸收,使所測得的結(jié)果更接近試驗(yàn)魚的營養(yǎng)消化生理要求。但Cho等[18]的計(jì)算方法并沒有考慮到基礎(chǔ)飼料和待測飼料原料的營養(yǎng)成分對(duì)測定結(jié)果的影響。本試驗(yàn)采用Bureau等[19-20]在Cho等[18]研究的基礎(chǔ)上提出的改進(jìn)計(jì)算方法(具體見公式2)進(jìn)行計(jì)算,進(jìn)一步減小了因基礎(chǔ)飼料與試驗(yàn)原料所含營養(yǎng)成分不同而產(chǎn)生的對(duì)被測飼料原料營養(yǎng)成分消化率的影響,提高了結(jié)果的準(zhǔn)確度。
根據(jù)指示劑及營養(yǎng)成分在飼料和糞便中的含量,間接測定動(dòng)物對(duì)飼料原料營養(yǎng)物質(zhì)的消化利用,是目前研究動(dòng)物對(duì)飼料消化率的主要方法。選擇合適的指示劑和糞便收集方法是影響測定營養(yǎng)物質(zhì)消化率準(zhǔn)確性的關(guān)鍵環(huán)節(jié)。三氧化二鉻是最早的,且應(yīng)用最多的指示劑。但是,飼料中的三氧化二鉻會(huì)改變魚類對(duì)飼料營養(yǎng)物質(zhì)的消化率,排放到水體后會(huì)對(duì)環(huán)境產(chǎn)生危害[21],并會(huì)使飼料的顏色變綠,進(jìn)而可能影響魚類的攝食。近年來,越來越多的研究者改用其他指示劑,如三氧化二釔[22-24],來避免以上負(fù)面作用。因此,本試驗(yàn)選用Y2O3為指示劑以確保數(shù)據(jù)的準(zhǔn)確性。
目前,糞便的收集方法主要有自然排糞法和體內(nèi)排糞法。自然排糞法的缺點(diǎn)是糞便中的營養(yǎng)成分不可避免地溶失于水中,造成消化率測定值偏高;體內(nèi)排糞法可能會(huì)采到一些還沒完全消化吸收的糞便,也可能會(huì)被血液、體液等污染,以致消化率測定值偏低[1]。網(wǎng)撈法作為自然排糞法的方法之一,具有操作簡單的優(yōu)點(diǎn),若收集的糞便是成型完整的[25],且在魚類排便后盡快收集[26],可以減少上述缺點(diǎn)的影響。在本試驗(yàn)中,吉富羅非魚成魚個(gè)體相對(duì)較大,排便量大、成型好。因此,選擇在試魚排便高峰期,用密網(wǎng)撈取糞便是可行的。
3.2 吉富羅非魚成魚對(duì)飼料原料粗蛋白和氨基酸的ADC
研究顯示,不同規(guī)格的羅非魚可以有效地利用大豆中的蛋白質(zhì),如7.18 g/尾奧尼羅非魚(Oreochromisniloticus♀×O.aureus♂)對(duì)豆粕粗蛋白的ADC為90.9%[12],15 g/尾尼羅羅非魚的為87.4%[2],93 g/尾尼羅羅非魚的為93.0%[3],100 g/尾尼羅羅非魚的為96.3%[11],250~400 g奧尼羅非魚的為94.61%[4]。在本試驗(yàn)中,全脂膨化大豆和豆粕粗蛋白的ADC分別為89.12%和91.20%,與之前的研究結(jié)果較為接近。同時(shí),比較各規(guī)格羅非魚對(duì)玉米蛋白粉[2,10,27]、菜粕[8,13,15]和花生粕[11,13]粗蛋白的ADC,發(fā)現(xiàn)與本試驗(yàn)所獲得的結(jié)果接近,表明羅非魚的規(guī)格并未影響其對(duì)豆粕、玉米蛋白粉、菜粕和花生粕中粗蛋白的消化。
棉粕中含有棉酚、環(huán)丙烯脂肪酸、植酸等抗?fàn)I養(yǎng)因子,會(huì)對(duì)魚類對(duì)其養(yǎng)分的利用產(chǎn)生負(fù)面影響[28]。但是隨著魚類的生長,抵抗力逐漸增強(qiáng),這種影響會(huì)減弱。如以生長為判斷依據(jù),對(duì)于11 g/尾的虹鱒,飼料中棉粕的用量在10%以下[29],39.2 g/尾則可以達(dá)到30%[30],而246 g/尾甚至可用到58.8%[31]。在本試驗(yàn)發(fā)現(xiàn),吉富羅非魚成魚對(duì)棉粕粗蛋白的ADC(94.41%)高于7.18 g/尾的奧尼羅非魚(77.6%[12])、93 g/尾和96.6 g/尾的尼羅羅非魚(79.4%[3],81.8%[27]),同時(shí)也高于320 g/尾的奧尼羅非魚 (82.13%[15]),表明吉富羅非魚成魚對(duì)棉粕的利用能力較強(qiáng)。
在本試驗(yàn)中,吉富羅非魚成魚對(duì)小麥麩粗蛋白的ADC僅為76.27%,與以往的報(bào)道[8,32]相近;對(duì)面粉的ADC高達(dá)101.12%,明顯高于之前羅非魚對(duì)小麥類原料粗蛋白ADC的報(bào)道[8,16,33],而與石斑魚(Sebastesschlegeli) (95%)[34]、大西洋鮭(Salmosalar)(98.3%)[22]、虹鱒(Oncorhynchusmykiss)(100.0%[22],112%[35])等魚類對(duì)面粉粗蛋白的ADC相近。造成此種差異的原因應(yīng)該是原料中不可消化碳水化合物的含量及種類不同所導(dǎo)致。如小麥麩的粗纖維含量要遠(yuǎn)高于面粉。一般認(rèn)為,魚類攝食纖維素含量高的飼料,可降低腸道蛋白酶活性,縮短食糜通過消化道時(shí)間,導(dǎo)致飼料蛋白質(zhì)消化率下降[36]。
從消化生理方面講,動(dòng)物(包括魚類)對(duì)蛋白質(zhì)的需求實(shí)質(zhì)上是對(duì)組成蛋白質(zhì)的氨基酸的需求。而必需氨基酸(EAA)因魚體不能合成或合成的量不足,需要從食物中獲取,因此了解飼料原料中EAA的消化率,對(duì)飼料的配制顯得尤為重要。在本試驗(yàn)中,吉富羅非魚成魚對(duì)各原料氨基酸和蛋白質(zhì)的ADC表現(xiàn)較為一致。從本試驗(yàn)的結(jié)果可以看出,除個(gè)別氨基酸外,豆粕、棉粕、花生粕、玉米蛋白粉和面粉EAA的ADC均在90%以上,全脂膨化大豆和菜粕的在85%以上,這表明,吉富羅非魚成魚對(duì)這7種原料中的大部分氨基酸都能有效地加以利用。但需要注意的是,植物性原料一般都會(huì)缺乏部分必需氨基酸,如在本試驗(yàn)中除玉米蛋白粉外,各原料Met的含量都很低。所以,在飼料的配制過程中需要注意利用各種原料氨基酸的互補(bǔ)性,以滿足羅非魚的生長或生理需要。
從本試驗(yàn)結(jié)果可以看出,吉富羅非魚成魚對(duì)全脂膨化大豆氨基酸的平均ADC稍低于豆粕,類似的結(jié)果在對(duì)尼羅羅非魚[13]、虹鱒[37]的研究中也有報(bào)道,這應(yīng)該與膨化作用改變了原料的部分氨基酸性質(zhì),降低了魚類的利用率有關(guān)。Jeunink等[38]經(jīng)檢測發(fā)現(xiàn),膨化后的大豆中半胱氨酸和胱氨酸總量會(huì)減少8.5%,而賴氨酸減少1.4%,從而直接證明氨基酸的性質(zhì)已發(fā)生變化。
3.3 吉富羅非魚成魚對(duì)粗脂肪、總能和總磷的ADC
在本試驗(yàn)中,各原料粗脂肪的ADC在89%以上,表明吉富羅非魚有很強(qiáng)的利用植物脂肪的能力,這與前人對(duì)奧尼羅非魚幼魚(7.18 g/尾)[12]、尼羅羅非魚(15 g/尾)[2]、奧尼羅非魚(100~150 g/尾)[8]的研究結(jié)果相近。在本試驗(yàn)中,吉富羅非魚成魚對(duì)面粉(92.81%)與小麥麩(94.20%)粗脂肪的ADC與紅擬石首魚(Sciaenopsocellatus)對(duì)小麥粗脂肪的ADC(87.9%)[39]相近,但明顯高于奧尼羅非魚(100~150 g/尾)對(duì)小麥(79.9%)、小麥麩(71.9%)[8]及尼羅羅非魚(100 g/尾)對(duì)面粉(67.37%)[7]的ADC。
植物性原料含有一些魚類難以消化的碳水化合物,如纖維素、半纖維素、木質(zhì)素等,會(huì)對(duì)能量的消化產(chǎn)生負(fù)面影響。這是因?yàn)椋环矫?,這些物質(zhì)不能被魚體消化,直接造成可消化能減少;另一方面,這些物質(zhì)的存在會(huì)降低其他可消化物質(zhì)的消化。本試驗(yàn)中,面粉總能的ADC高達(dá)103.50%,表明面粉是吉富羅非魚成魚優(yōu)質(zhì)的的能量來源,而小麥麩的僅為39.91%,這應(yīng)該與小麥麩所含的不可消化的碳水化合物過多有關(guān)[8,40]。在本試驗(yàn)中,吉富羅非魚成魚對(duì)全脂膨化大豆(90.09%)、花生粕(94.64%)和玉米蛋白粉(86.57%)總能的ADC顯著高于棉粕(64.99%)和菜粕(62.92%)。分析認(rèn)為,全脂膨化大豆中的脂肪含量最高,而花生粕和玉米蛋白粉的粗蛋白較高,相對(duì)的降低了難以消化的碳水化合物的含量,從而獲得了較高的總能ADC。
磷是魚類重要的礦物營養(yǎng)元素。它在植物性原料中主要以植酸磷的形式存在,一般較難被魚類所利用。如團(tuán)頭魴(Megalobramaamblycephala)對(duì)菜粕、花生粕以及棉粕總磷的ADC僅為3.21%,11.81%和17.70%[41]。但也有研究報(bào)道,青魚(Mylopharyngodonpiceus)[42]、矛尾復(fù)蝦虎魚(Synechogobiushasta)[43]等對(duì)豆粕、菜粕、花生粕中磷的ADC可達(dá)50%以上。在本試驗(yàn)中,全脂膨化大豆、豆粕和花生粕中磷的ADC在32.96%~38.90%,棉粕、菜粕和小麥麩的磷ADC在51.45%~59.87%,玉米蛋白粉的為83.39%。而對(duì)比羅非魚的相關(guān)研究發(fā)現(xiàn),15 g/尾的尼羅羅非魚對(duì)豆粕中磷的ADC為30.1%,對(duì)玉米蛋白粉中磷的ADC為28.2%[2];7.18 g/尾的奧尼羅非魚對(duì)豆粕、花生粕、菜粕和棉粕中磷的ADC在52.7%~58.6%[12],25.24 g/尾的尼羅羅非魚對(duì)加拿大雙低菜粕中磷的ADC為29.86%[44]。推測產(chǎn)生這些差異的主要原因應(yīng)該與魚的種類、原料化學(xué)組成及生產(chǎn)加工工藝等不同有關(guān)。在本試驗(yàn)中,面粉中磷的消化率遠(yuǎn)高于100%,這與面粉中磷的含量較低有關(guān),類似的結(jié)果在日本海鱸(Lateolabraxjaponicus)[45]的研究中也有報(bào)道。
綜上所述,吉富羅非魚成魚對(duì)不同原料中的營養(yǎng)物質(zhì)和總能的ADC差異較大。但總體而言,除小麥麩外,吉富羅非魚成魚對(duì)各原料的粗蛋白和氨基酸ADC均較高,然而飼料配方中使用這些原料仍需注意氨基酸的不平衡問題;吉富羅非魚成魚能有效地利用各種飼料原料中的脂肪;對(duì)各飼料原料能量的利用差異較大,以面粉最高,花生粕、玉米蛋白粉和全脂膨化大豆其次,豆粕、棉粕和菜粕再次,小麥麩最低,在使用豆粕、棉粕和菜粕作為配方的主要原料時(shí),要考慮能量是否充足;原料中總磷的ADC有較大差異,在配方的制定時(shí)應(yīng)注意添加適量的磷。
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Apparent digestibility coefficients of adultOreochromisniloticusto ingredients of eight common botanical feeds
LIU Wei,WEN Hua,JIANG Ming,WU Fan,TIAN Juan,YANG Chang-geng
(KeyLaboratoryofFreshwaterBiodiversityConservationandUtilization,MinistryofAgriculture,YangtzeRiverFisheriesResearchInstitute,ChineseAcademyofFisherySciences,Wuhan,Hubei430223,China)
【Objective】 To improve the precision of feed formulation,apparent digestibility coefficients (ADC) of adultOreochromisniloticusto nutrient and total energy of eight common botanical feeds were determined.【Method】 ADC values of adultOreochromisniloticus((290.6±5.8) g) to crude protein (ADCp),lipid (ADCl),energy (ADCe),phosphorus (ADCps) and amino acids (ADCa) in six botanical protein ingredients (extruded full-fat soybean meal,soybean meal,cottonseed meal,rapeseed meal,peanut meal and corn gluten meal) and two botanical energy ingredients (wheat bran and wheat flour) were determined using a reference diet.Test diets contained 70% reference diet and 30% feed ingredients by weight.Fecal materials (intact strands) were collected with a fine-mesh net after one week.【Result】 ADCp,ADCe and average ADCa values were highest in wheat flour and lowest in wheat bran.ADCl values in all feed ingredients were above 89.24%,showing no significant differences among treatments (P>0.05).The ADC of amino acids had a positive correlation with ADC of crude protein for a given ingredient.ADCp,average ADCa,ADCe and ADCps of the six plant protein sources ranged from 85.70% to 94.41%,89.07% to 95.87%,62.92% to 94.64% and 32.96% to 83.39%,respectively.In the six botanical protein sources,ADCps values were more than 89% in extruded full-fat soybean meal,soybean meal,cottonseed meal,peanut meal and corn gluten meal,with no remarkable differences among these ingredients (P>0.05).ADCe values in full-fat soybean meal,peanut meal and corn gluten meal were significantly higher (P<0.05) than in cotton seed meal and rapeseed meal,and ADCps value in corn gluten meal was significantly higher (P<0.05) than in the others.【Conclusion】 Corn gluten meal,peanut meal,extruded full-fat soybean meal and soybean meal could be used as sources of high quality protein sources for adultOreochromisniloticus,and wheat flour could be used as superior energy source.
adultOreochromisniloticus;botanical ingredients;apparent digestibility
2013-11-25
中國水產(chǎn)科學(xué)研究院基本科研業(yè)務(wù)費(fèi)項(xiàng)目(2012A0602);現(xiàn)代農(nóng)業(yè)產(chǎn)業(yè)技術(shù)體系建設(shè)專項(xiàng)資金項(xiàng)目(CARS-49);農(nóng)業(yè)部公益性行業(yè)科研專項(xiàng)經(jīng)費(fèi)項(xiàng)目(201003020)
劉 偉(1982-),男,江蘇徐州人,助理研究員,碩士,主要從事魚類營養(yǎng)與飼料研究。E-mail:liuwei@yfi.ac.cn
文 華(1965-),男,湖北荊州人,研究員, 博士,主要從事水產(chǎn)動(dòng)物營養(yǎng)與飼料研究。 E-mail:wenhua.hb@163.com
時(shí)間:2015-03-12 14:17
10.13207/j.cnki.jnwafu.2015.04.030
S964.6
A
1671-9387(2015)04-0017-09
網(wǎng)絡(luò)出版地址:http://www.cnki.net/kcms/detail/61.1390.S.20150312.1417.030.html