適用鰻苗循環水養殖系統之高成長膏狀飼料開發

Abstract

目前臺灣之鰻魚養殖業者多以赤蟲及絲蚯蚓作為鰻苗初期之開口餌料，取其對鰻苗具有強誘引性及良好適口性。但二種餌料皆生活於富含有機質之水域，容易夾帶病原或寄生蟲進養殖環境中，特別對於封閉集約式的循環水養殖系統有嚴重威脅。所以日本及韓國目前皆以人工膏狀飼料作為鰻苗之開口與初期餌料，其誘引性及適口性與赤蟲／絲蚯蚓接近，然其缺點為進口售價過於高昂，並不符合養殖經濟效益。而當鰻苗成長進入幼鰻階段後，目前主流使用鰻粉或浮料進行餵飼。其中鰻粉的散失性極強，容易對養殖池之水質造成嚴重影響，且易造成物理過濾器過載；浮料則由於加工過程需經過高溫膨發，無法在製程中有效添加對鰻魚成長、抗病有益之添加物如益生菌等，且初期鰻苗無法攝食。而膏狀飼料具有不易散失及低溫製作之特性，非常容易於製程中添加各種有利於鰻魚之添加物。若能研發出價格合理之鰻苗膏狀飼料，具有良好適口性及誘引性，散失性低，再加以功能性添加劑，極適合使用在室內集約循環水養殖系統，將具有龐大的商業潛力。本研究目前已研發出ㄧ種以魷魚漿搭配魚卵所製成之膏狀飼料，且發現對各類鰻苗之適口性、誘引性良好且成長表現不遜於赤蟲，更檢測不出對鰻魚有害之病原菌，極為適合搭配室內循環水系統使用。若搭配良好之機能性添加劑 (碳化多銨 (CQDSpds)、納豆枯草桿菌NTU-18)等可以進一步提升鰻苗之成長表現、抗病能力及腸道菌相，且不會影響鰻苗之腸道型態。

Currently, in Taiwan, eel aquaculture farmers mostly use bloodworms as initial feed, taking advantage of their strong attractiveness and palatability to glass eel. However, both types of feed live in waters rich in organic matter, making them prone to carry pathogens or parasites into the aquaculture systems, especially to the intensive eel recirculating aquaculture systems (RAS). Therefore, Japan currently using artificial paste feed as the initial feed for glass eel, which has similar attractiveness and palatability to bloodworms. However, its excessively high price, which is not cost efficiency. As glass eel grow into the elver stage, the main using feed used is eel powder or floating feed. Eel powder is highly dispersible, easily causing serious water quality impacts in aquaculture systems, and can overload RAS physical filters. Floating feed, due to the high-temperature required during processing, cannot effectively add beneficial additives such as probiotics for eel growth and disease resistance, and a glass eel cannot consume. Paste feed, on the other hand, has the characteristics of good stability and processed under low temperatures, making it very easy to add various additives beneficial to eel growth during processing. If a paste feed with good palatability, attractiveness, low dispersibility, reasonably priced, and additives can be easily added was developed, it will be extremely suitable for use in indoor intensive RAS. This study has currently developed a paste feed made from squid paste combined with fish roes, which has been found to have good palatability and attractiveness to various species of glass eels and performance comparable growth performance with bloodworms. Furthermore, harmful pathogens for eels were not detected in the glass eel intestine, making it highly suitable for use in indoor intensive RAS. If combined with good functional additives (CQDSpds, Bacillus subtilis natto NTU-18), it can further enhance the growth performance, disease resistance, immune gene response and intestinal microbiota of glass eel without affecting their intestinal morphology.