Investigation of potential bio-active properties and effects on production performance of aquafeed ingredients derived from fish processing waste by way of enzymatic autolysis

Goosen, Neill Jurgens (2014-12)

Thesis (PhD) -- tellenbosch University, 2014.

Thesis

ENGLISH ABSTRACT: This study is part of the continuing global research effort dedicated to finding alternative aquafeed ingredients, which not only replace fish meal and fish oil as sources of essential nutrients in aquafeeds, but also provide specialist functional properties when included in feeds. Due to constraints in supply of fish meal and fish oil originating from wild capture fisheries, the continually growing aquafeed industry requires new sources of raw materials for the production of high quality feeds. The aim of the study was to investigate the specialist functional properties of feed ingredients (with emphasis on immune-stimulation potential) derived from fish processing waste after enzymatic hydrolysis by endogenous proteolytic enzymes (autolysis). Further aims were to (i) quantify effects of these feed ingredients on production performance of two species relevant to the South African aquaculture industry, namely Mozambique tilapia Oreochromis mossambicus and South African abalone Haliotis midae, (ii) compare performance to commercially available enzymatically produced feed ingredients, and (iii) separate the functional effects of these fish processing waste derived feed ingredients from the acid used to preserve them against bacterial spoilage during the autolysis process. Oil recovered after autolysis of rainbow trout viscera proved to be an attractive feed ingredient due to favourable effects on the non-specific cellular immune function of both Mozambique tilapia and South African abalone. However, in South African abalone, increased immune function due to inclusion of fish oil was accompanied by a significant decrease in production performance. The inclusion of hydrolysed proteins, obtained by autolysis of fish waste, in aquaculture feeds also improved non-specific immunity and survival of Mozambique tilapia significantly – independently of the preserving acid – although the same was not observed for South African abalone. Production performance was dependent on dietary hydrolysed protein inclusion levels in both species; excessive inclusion resulted in decreased production performance. The performance of dietary hydrolysed protein from autolysis and those from commercial production processes were significantly different, possibly as a result of different raw material origins and production processes. It is further shown that formic acid can contribute to improved water stability in abalone feeds, a novel mode of action not previously described. The study concludes that the simple autolysis process for processing of fish waste can provide aquafeed ingredients with immune stimulatory potential, which can contribute to improved production performance in the Mozambique tilapia and the South African abalone. The result can contribute to improved sustainability of the aquafeed industry, through substitution of fish meal and fish oil derived from capture fisheries with processed fish waste components.

AFRIKAANSE OPSOMMING: Hierdie studie vorm deel van die voortdurende en wêreldwye soeke na nuwe akwakultuur voerbestanddele wat nie net vismeel en –olie kan vervang as bron van noodsaaklike voedingstowwe nie, maar wat ook gespesialiseerde funksionele eienskappe openbaar wanneer dit in akwavoere ingesluit word. As gevolg van beperkings in die voorsiening van vismeel en –olie afkomstig vanaf wilde visserye, word die voortdurend groeiende akwavoer bedryf genoodsaak om nuwe grondstowwe te benut vir die vervaardiging van hoë kwaliteit voere. Die doelwit van die studie was om moontlike gespesialiseerde funksionele eienskappe (met spesifieke klem op potensiële immuun-stimulasie) van voerbestanddele te ondersoek wat herwin is vanaf reënboogforel proseseringsafval, na ensiematiese hidrolise d.m.v. endogene ensieme teenwoordig in die afval (outolise). Verdere doelwitte was om (i) effekte op produksie prestasie van hierdie bestanddele te kwantifiseer in twee akwakultuur spesies relevant tot die Suid- Afrikaanse bedryf (naamlik die Mosambiekse kurper Oreochromis mossambicus en die Suid- Afrikaanse perlemoen Haliotis midae), (ii) om produksie prestasie te vergelyk met kommersieel beskikbare voerbestanddele voorberei d.m.v. ensiemtegnologie, en (iii) om die moontlike effekte van die voerbestanddele te skei van die van die sure gebruik om die bestanddele te preserveer tydens die outolitiese proses. Daar is bevind dat olie herwin na outolise van reënboogforel ingewande ‘n goeie voerbestanddeel is wat gunstige effekte op die nie-spesifieke, sellulêre immuniteit van beide Mosambiekse kurper en Suid-Afrikaanse perlemoen gehad het. In die Suid-Afrikaanse perlemoen het verbeterde immuunfunksie gepaard gegaan met ‘n verswakking in produksie prestasie. Die gehidroliseerde proteïen komponent van ge-outoliseerde prosesseringsafval het ook beduidende verbetering in nie spesifieke immuniteit en oorlewing van Mosambiekse kurper tot gevolg gehad - onafhanklik van die preserverende suur - maar dieselfde is nie in die Suid-Afrikaanse perlemoen waargeneem nie. Produksie prestasie was afhanklik van die insluitingsvlakke van gehidroliseerde proteïen in beide spesies en dit is bevind dat oormatige insluiting produksie nadelig beïnvloed. Prestasie van proteïen afkomstig van outolise en die van ‘n kommersiële produksieproses het beduidend verskil, moontlik as gevolg van verskillende grondstowwe en prosesseringstegnieke. Daar is verder vir die eerste keer getoon dat mieresuur ‘n beduidende verbetering in waterstabiliteit in sekere perlemoenvoere teweeg kan bring. Die studie kom tot die slotsom dat die eenvoudige outolise proses funksionele akwavoerbestanddele kan produseer wat kan bydra tot ‘n verbetering in produksie prestasie in die Mosambiekse kurper en Suid-Afrikaanse perlemoen. Die resultaat kan bydra tot verbeterde volhoubaarheid van die akwavoer bedryf, deur vismeel en –olie afkomstig van wilde visserye, te vervang.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/95907
This item appears in the following collections: