軍曹魚是一種大的沿海的遠(yuǎn)洋魚，主要分布在全球熱帶、亞熱帶水域，除了東太平洋以外（Brown-Peterson et al., 2002)。海面網(wǎng)箱系統(tǒng)飼養(yǎng)軍曹魚，一年的時(shí)間軍曹魚可由小魚長到4-6kg的上市體重，并且飼料轉(zhuǎn)化率很高。軍曹魚的白魚肉適合做生魚片(Chou et al., 2001)。目前，在中國限制供應(yīng)垃圾魚作為軍曹魚的主要食物來源，而且已經(jīng)這已經(jīng)成為軍曹魚文化的主要限制點(diǎn)。垃圾魚儲(chǔ)存困難，營養(yǎng)價(jià)值多變，而且飼料轉(zhuǎn)化率低。因此，營養(yǎng)全面、低成本的軍曹魚配方飼糧代特垃圾魚將是今后研究的重點(diǎn)，也很有發(fā)展前途。
從1984 到 1997，全球的水產(chǎn)品以每年大約12%的速度增長，一部份的原因就是由于配方飼糧的可利用性在不斷增加(Tacon and Dominy, 1999)。在很多配方飼糧中，魚粉被用作蛋白質(zhì)原料，這是因?yàn)轸~粉中必需氨基酸和必需脂肪酸含量高，碳水化合物含量低，消化性好，并且抗?fàn)I養(yǎng)因子含量低。魚粉被公認(rèn)為是最好的海洋肉食性魚飼糧的蛋白質(zhì)來源。與雜食性和草食性魚相比，肉食性魚需要更高水平的蛋白質(zhì)(NRC, 1993)。然而，全球捕撈的魚有大約35%用來加工魚粉(Tacon and Dominy, 1999)，并且價(jià)格的增高以及市場潛在的不穩(wěn)定的供應(yīng)可能會(huì)成為海洋漁業(yè)的限制因素，阻礙海洋漁業(yè)的發(fā)展。因此，尋求與分的替代品和有選擇性的飼糧蛋白質(zhì)來源已經(jīng)成為國際性的急需解決的問題，也是可以帶來巨大經(jīng)濟(jì)利益的研究(Lee, 2002)。這在中國尤為重要，因?yàn)樵谥袊哔|(zhì)量的魚粉較少，但價(jià)格低廉的農(nóng)業(yè)蛋白來源卻很多，比如動(dòng)物粉、含油種子、谷物豆類和谷類食品都是可利用的。
測定營養(yǎng)成分的可消化率是評(píng)價(jià)一種水產(chǎn)品種飼料原料潛在價(jià)值的第一步(Allan et al., 2000)。飼料成分消化系數(shù)的有關(guān)信息是非常有用的。不僅對(duì)配制日糧（要達(dá)到最好的生長效果需要添加多少有效養(yǎng)分）而且對(duì)限制垃圾魚產(chǎn)品都是有幫助的(Lee, 2002)。目前，只有一些暖水海洋中肉食性動(dòng)物的常規(guī)飼料成分的消化系數(shù)被報(bào)道(NRC, 1993).，而有關(guān)軍曹魚對(duì)蛋白飼料原料的表觀消化系數(shù)卻還沒有報(bào)道。本試驗(yàn)的目的就是對(duì)飼喂幼軍曹魚的飼料原料中的干物質(zhì)、粗蛋白、粗脂肪、總能量、磷和氨基酸的表觀消化系數(shù)進(jìn)行測定。飼料原料主要有秘魯魚粉、脫脂大豆餅、溶劑萃取物、家禽肉骨粉、花生餅粉、油菜籽粉、玉米面粉和玉米麩皮。
2 材料和方法
2.1 試驗(yàn)日糧的準(zhǔn)備
配制標(biāo)準(zhǔn)日糧(RF)用來滿足軍曹魚蛋白質(zhì)和脂肪的營養(yǎng)需求(Chou et al., 2001)，見表1。按照Cho and Slinger (1979)配制8種試驗(yàn)日糧（由70%標(biāo)準(zhǔn)日糧和30%每種試驗(yàn)飼料成分組成）。在標(biāo)準(zhǔn)日糧和試驗(yàn)日糧中各添加0.5%Cr2O3 作為外指示劑。試驗(yàn)飼料原料中的營養(yǎng)成分和試驗(yàn)日糧的氨基酸組成分別見表2和表3。在干的預(yù)混料中加入水和油脂，在Hobart型混合機(jī)中充分混合。濕法擠壓制成直徑為3mm的球形飼料，經(jīng)空氣干燥使其含水量為10%，裝入塑料袋內(nèi)，-20℃冷凍保存。
軍曹魚可以很好的消化幾乎所有試驗(yàn)飼料成分中的粗蛋白和粗脂肪。這與一些關(guān)于肉食性海魚的報(bào)道相符合，例如駝背鯰科魚(Laining et al., 2003)，紅鼓魚(Gaylord and Gatlin,1996; McGoogan and Reigh, 1996)，和鯡魚(Masumota et al., 1996)。在目前的研究中，蛋白消化系數(shù)為90%以上的飼料成分有魚粉、家禽份、玉米麩皮粉、脫脂大豆粉/餅和浸提大豆餅、花生餅粉等，它們的蛋白含量范圍為42.60%~ 72.65%。低蛋白消化系數(shù)的飼料成分有油菜籽粉（因含有抗?fàn)I養(yǎng)成分較受關(guān)注）和肉骨粉。這些原料中干物質(zhì)的表觀消化率一般都很低，尤其是植物性原料。其表觀消化系數(shù)范圍為58.52%（油菜籽粉）~84.58%（玉米麩皮粉）。相比較而言，動(dòng)物源性飼料成分的表觀消化率比較好，如魚粉和家禽粉。在所有試驗(yàn)的動(dòng)物飼料成分中，肉骨粉的表觀消化率最低。
在當(dāng)前的研究中，幼軍曹魚可以消化所有試驗(yàn)飼料成分中的能量，在所有試驗(yàn)的飼料成分中，除了玉米面粉外，植物源性成分能量的表觀消化率都低于動(dòng)物源性飼料成分。類似于紅鼓魚(Gaylord and Gatlin, 1996; McGoogan and Reigh, 1996)和巖魚(Lee, 2002)的研究結(jié)果。植物性原料中能量的消化率低是因?yàn)槠涮妓衔锖扛卟⑶液茈y被肉食性魚消化(Lupatsch et al., 1997)。
正因?yàn)轸~粉的粗蛋白、粗脂肪以及能量的消化性較高，并且氨基酸的利用率很高，所以飼料制造商選魚粉作為水產(chǎn)飼料配方中蛋白的主要來源(Allan et al., 2000)。對(duì)幼軍曹魚來說，其它一些原料的消化系數(shù)和魚粉相似，包括家禽粉和玉米麩皮粉。家禽粉和玉米麩皮粉有高的總蛋白含量、高的總能消化率、高含量粗蛋白和粗脂肪，這些和魚粉相似。但和魚粉相比，那些消化性好且蛋白含量高的飼料原料還有不足之處，那就是無論是必需氨基酸含量、氨基酸品質(zhì)還是氨基酸的可利用率都不如魚粉。不僅幼軍曹魚對(duì)魚粉的消化系數(shù)很高，其它種類的魚也一樣，包括：澳大利亞銀鱸(Allan et al., 2000)、海峽鯰魚(Robinson, 1989; Wilson, 1991)、鯉魚(Jauncey, 1982)、歐洲鰻魚(Schmitz et al., 1984)、駝背鯰魚(Laining et al.,2003)、雜種條紋石魚(Sullivan and Reigh, 1995)、巖魚(Lee, 2002)、虹鱒魚(Gomes et al., 1995; Smith et al., 1995; Bureau et al., 1999; Cheng and Hardy, 2002)、紅鼓魚(Gaylord and Gatlin, 1996; McGoogan and Reigh, 1996)、大西洋鮭魚(Storebakken et al., 1998; Sugiura et al., 1998)、尼羅河羅非魚(Hanley, 1987)。
氨基酸的可用系數(shù)在一定程度上反映了高消化性原料中蛋白的消化系數(shù)，例如，秘魯魚粉和玉米麩皮粉。與試驗(yàn)的其它動(dòng)物性和植物性日糧相比，肉骨粉中賴氨酸的可用系數(shù)較低，這說明在粉碎加工中熱賴氨酸的熱破壞較嚴(yán)重(Opsvedt et al., 1984)。軍曹魚對(duì)飼料原料中的蛋氨酸有很好的消化性，雖然在油菜籽粉中蛋氨酸的可利用很低。
眾所周知，以植酸磷形式存在的磷不能被魚利用，因在魚的腸道里不存在可消化植酸磷的微生物植酸酶(Opsvedt et al., 1984)。植物種子中含有植酸酶，并且不受熱處理的影響。但與玉米面粉相比，油菜籽粉和花生中的植酸酶的活性很低(Pointillart, 1994)。玉米面粉中磷的表觀消化系數(shù)很高，這是因?yàn)槠渲菜崃缀涂偭椎暮慷际亲畹偷?。在所有的?dòng)物性原料中肉骨粉中磷的表觀消化率最低，雖然其總磷含量最高。這說明，食入的磷的濃度越低，軍曹魚對(duì)磷消化性越好，這與虹鱒魚、大菱鲆還有大西洋鮭魚的報(bào)道結(jié)果一致(Vielma and Lall, 1997; Burelet al., 2000)。
Allan, G.L., Parkinson, S., Booth, M.A., Stone, D.A.J., Rowland, S.J., Frances, J., Warner-Smith, R., 2000.Replacement of fish meal in diets for Australian silver perch, Bidyanus bidyanus: I. Digestibility of alternativeingredients. Aquaculture 186, 293– 310.
AOAC, 1995. Official Methods of Analysis of AOAC, 16th edn. In: Helric, K. (Ed.), Association of Analytical Chemist, Inc., Arlington, VA.
Brown-Peterson, N.J., Grier, H.J., Overstreet, R.M., 2002. Annual changes in germinal epithelium determinemale reproductive classes of the cobia. J. Fish Biol. 60, 178–202.
Bureau, D.P., Harris, A.M., Cho, C.Y., 1999. Apparent digestibility of rendered animal protein ingredients for rainbow trout (Oncorhynchus mykiss). Aquaculture 180, 345– 358.
Burel, C., Boujard, T., Tulli, F., Kaushik, S.J., 2000. Digestibility of extruded peas, extruded lupin, and rapeseed meal in rainbow trout (Oncorhynchus mykiss) and turbot (Psetta maxima). Aquaculture 188, 285– 298.
Cheng, Z.J., Hardy, R.W., 2002. Apparent digestibility coefficients and nutritional value of cottonseed meal for rainbow trout (Oncorhynchus mykiss). Aquaculture 212, 361– 372.
Cho, C.Y., Kaushik, S.J., 1990. Nutritional energetics in fish: energy and protein utilization in rainbow trout (Salmo gairdneri). World Rev. Nutr. Diet. 61, 132– 172.
Cho, C.Y., Slinger, S.J., 1979. Apparent digestibility measurement in feedstuff for rainbow trout. In: Halver, J.E.,Tiews, K. (Eds.), Finfish Nutrition and Fishfeed Technology, vol. II. Heeneman, Berlin, pp. 239– 248.
Cho, C.Y., Slinger, S.J., Bayley, H.S., 1982. Bioenergetics of salmonid fishes: energy intake, expenditure and productivity. Comp. Biochem. Physiol. 73B, 25– 41.
Chou, R.L., Su, M.S., Chen, H.Y., 2001. Optimal dietary protein and lipid levels for juvenile cobia (Rachycentron canadum). Aquaculture 193, 81– 89.
Duncan, D.B., 1955. Multiple-range and multiple F tests. Biometrics 11, 1– 42.
Gaylord, T.G., Gatlin III, D.M., 1996. Determination of digestibility coefficients of various feedstuffs for red drum (Sciaenops ocellatus). Aquaculture 139, 303– 314.
Gomes, E.F., Rema, P., Kaushik, S.J., 1995. Replacement of fish meal by plant proteins in the diet of rainbow trout (Oncorhynchus mykiss): digestibility and growth performance. Aquaculture 130, 177– 186.
Hanley, F., 1987. The digestibility of foodstuffs and the effects of feeding selectivity on digestibility determinations in tilapia Oreochromis niloticus (L.). Aquaculture 66, 163– 179.
Hossain, M.A., Nahar, N., Kamal, M., 1997. Nutrient digestibility coefficients of some plant and animal proteins for rohu (Labeo rohita). Aquaculture 151, 37– 45.
Jauncey, K., 1982. Carp (Cyprinus carpio L.) nutrition—a review. In: Muir, J.F., Roberts, R.J. (Eds.), Recent Advances in Aquaculture. Croom Helm, London, UK, pp. 217–263.
Laining, A., Rachmansyah, Ahmad, T., Williams, K., 2003. Apparentdigestibility of selected feed ingredient for humpback grouper Cromileptes altivelis. Aquaculture 218, 529–538.
Lall, S.P., 1991. Digestibility, metabolism and excretion of dietary phosphorus in fish. In: Cowey, C.B., Cho, C.Y.(Eds.), Nutritional Strategies and Aquaculture Wastes. Proceedings of the First International Symposium on Nutritional Strategies in Management of Aquaculture Wastes. University of Guelph, Guelph, Ontario, Canada,pp. 21– 26.
Lee, S.M., 2002. Apparent digestibility coefficients of various feed ingredients for juvenile and grower rockfish (Sebastes schlegeli). Aquaculture 207, 79–95.
Lupatsch, I., Kissil, G.W., Sklan, D., Pfeffer, E., 1997. Apparent digestibility coefficients of feed ingredients and their predictability in compound diets for gilthead seabream Sparus aurata L. Aquac. Nutr. 3, 81– 89.450 Q.-C. Zhou et al. / Aquaculture 241 (2004) 441–451
Masumota, T., Ruchimat, T., Ito, Y., Hosokawa, H., Shimeno, S., 1996. Amino acid availability values for several protein sources for yellowtail (Seriolaquinqueradiata). Aquaculture 146, 109– 119.
McGoogan, B.B., Reigh, R.C., 1996. Apparent digestibility of selected ingredients in red drum (Sciaenops ocellatus) diets. Aquaculture 141, 233– 244.
National Research Council (NRC), 1993. Nutrient Requirements of Fish. National Academy Press, Washington, DC. 114 pp.
Opsvedt, J., Miller, R., Hardy, R.W., Spinelli, J., 1984. Heat-induced changes in sulfhydryl groups and disulfide bonds in fish protein and their effect on protein digestibility in rainbow trout (Salmo gairdneri). J. Agric.Food Chem. 32, 929– 935.
Pointillart, A., 1994. Phytates, phytases: leur importance dans le limentation des monogastriques (Phytates and phytases: their relevance in the feeding of pigs and poultry). INRA Prod. Anim. 7, 29– 39.
Schmitz, O., Greuel, E., Pfeffer, E., 1984. Digestibility of crude protein and organic matter of potential sources of dietary protein for eels (Anguilla anguilla L.). Aquaculture 41, 21– 30.
Smith, R.R., Winfree, R.A., Rumsey, G.W., Allred, A., Peterson, M., 1995. Apparent digestion coefficients and metabolizable energy of feed ingredients for rainbow trout Oncorhynchus mykiss. J. World Aquac. Soc. 26,432–437.
Storebakken, T., Shearer, K.D., Roem, A.J., 1998. Availability of protein, phosphorus and other elements in fish meal, soy–protein concentrate and phytase-treated soy–protein-concentrate-based diets to Atlantic salmonSalmo salar. Aquaculture 161, 365– 379.
Sugiura, S.H., Dong, F.M., Rathbone, C.K., Hardy, R.W., 1998. Apparent protein digestibility and mineral availabilities in various feed ingredients for salmonid feeds. Aquaculture 159, 177–202.
Sullivan, J.A., Reigh, R.C., 1995. Apparent digestibility of selected feedstuffs in diets for hybrid striped bass (Morone saxatilin_Morone chrysops). Aquaculture 138, 313–322.
Tacon, A.G.J., Dominy, W.G., 1999. Overview of world aquaculture and aquafeed production. Book of Abstracts.World Aquaculture’ 99, 26 April-2 May 1999, Sydney, Australia. World Aquaculture Society, Baton Rouge,LA. 853 pp.