Application of exogenous enzymes in Haliotis midae diets with soybean meal as fish meal replacement

De Villiers, Christopher Murray (2012-03)

Thesis (MSc)--Stellenbosch University, 2012.

Thesis

ENGLISH ABSTRACT: A 240-day growth study was conducted to determine the suitability of soybean meal (SBM) as an alternative protein source to fish meal (FM) in the diet of commercially produced South African abalone (Haliotis midae). The suitability of SBM was determined by a close evaluation of the following key factors: feed water stability, morphological impact on the abalone intestine and the effect on the growth performance of abalone. The study was comprised of two phases: a fish meal replacement phase (Phase A) and an enzyme treatment phase (Phase B). Diets used in Phase A consisted of a control fish meal diet (Control=22%FM, 0%SBM), a fish meal-soybean meal diet (FMSBM=20%FM, 15%SBM), a soybean meal-low diet (SBMlow=0%FM, 15%SBM) and a soybean meal diet (SBM=0%FM, SBM30%). In Phase B, the FM diet and SBM diet were used as basal diets (FME0 and SBME0). These diets were then treated with three commercial enzyme products, namely, a β- glucanase (FME1 and SBME1), xylanase (FME2 and SBME2) and α-D-galactosidase (FME3 and SBME3). Subsequently, all three enzymes were combined to make two treatments (FME123 and SBME123). With regard to the gut morphology and growth trials, a thirteenth energy enhanced commercial animal protein-free diet (ECO) was used. In Phase A (fish meal replacement), the findings revealed that water stability did not differ significantly between treatments. In Phase B (enzyme treatment) however, the water stability of β- glucanase treated feeds was significantly lower than that of the control FM diet. It was also observed that in comparison to the control FM diet, soybean meal based diets have a significantly greater effect on intestinal morphology. With reference to Phase A (fish meal replacement), by the end of the 240 day growth trial period, it was evident that animals fed on the commercial (ECO) diet were significantly heavier than those given the control FM diet. With regard to final length in mm, feed conversion ratio (FCR) and specific growth rate (SGR) for mass and length, no differences between the treatments were noted. It was also found that the condition of the ECO fed animals was significantly better in comparison to the other treatment fed animals. No significant differences were observed between the FM and three FMreplaced diets however. With reference to Phase B (enzyme treatment), it was noted that once again, after the 240 day period, abalone fed on the ECO diet were significantly heavier in terms of their final weight when compared to those fed on the other diets. As in Phase A, no differences in FCR and SGR for mass and length were observed. Measurements of the animals’ final length (as observed on day 240) revealed that those fed on the ECO diet were significantly longer than those given the FME1, SBME1 and SBME3 diets. At the end of the trial, abalone fed on the ECO diet were also in significantly better condition than those fed on the SBM, FME3 and FME123 diets. In terms of production performance, no significant difference was found between the SBM diets and FM diets and enzyme supplementation did not significantly increase the production performance either. The results of this study therefore show that SBM has great potential to be used as a FM-replacement diet. The improved performance of the ECO diet was expected due to its energy content.

AFRIKAANSE OPSOMMING: ‘n Groeistudie is gedoen met die perlemoen (Haliotis midae) oor ʼn tydperk van 240 dae om die geskiktheid van sojaboonoliekoek (SBM) as ‘n alternatiewe proteïenbron ter vervanging van vismeel (FM) in die rantsoen te evalueer. Geskiktheid van SBM is getoets aan die hand van waterstabiliteit van voer, morfologie van die spysverteringskanaal en die invloed daarvan op groei van die perlemoen. Die studie het uit twee fases bestaan naamlik ‘n vismeel (FM) vervangingsfase (Fase A) gevolg deur ‘n ensiem behandelingsfase (Fase B). Die diëte wat gebruik was sluit in ’n Kontrole dieet wat slegs vismeel as proteïenbron bevat (Kontrole = 22%FM, 0%SBM), ‘n 2de dieet wat beide vismeel en sojaboonoliekoekmeel bevat (FMSBM =20%FM, 15% SBM), ‘n 3de dieet wat ‘n lae vlak sojaboonoliekoekmeel bevat (SBMlow =0%FM, 15%SBM) en 4de dieet met ʼn hoër sojaboonoliekoek vlak (SBM = 0%FM, 30% SBM). Die basale diëte van Fase B was dieselfde as die FM en SBM diëte van Fase A (FME0 en SBM0) met die verskil dat dit met kommersiële ensieme behandel is. Die onderskeie behandelings was gedoen met β-glukanase (FME1 en SBME1), xylanase (FME2 en SBME2) en α-D-galactosidase (FME3 en SBME3) asook ‘n kombinasie van die drie ensieme (FME123 en SBME123). ‘n Addisionele behandeling bestaande uit ‘n kommersiële diereproteïenvrye dieet (ECO) is as bygevoeg as kontrole vir die histologie gedeelte van die proef. Tydens Fase A is gevind dat waterstabiliteit van die onderskeie diëte nie betekenisvol verskil het nie. Tydens Fase B het ensiembehandeling met β-glukanase egter aanleiding gegee tot betekenisvolle laer waterstabiliteit van FME1 en SBME1 diëte in vergelyking met die FM dieet. Histologiese ontledings het getoon dat die SBM diëte ‘n groter negatiewe effek op die morfologie van die spysverteringkanaal gehad het as die kontrole FM dieet. Fase A het getoon dat die ECO dieet beter groeiresultate opgelewer het as die FM dieet, in terme van liggaamsmassa en kondisiefaktor van die perlemoen. Finale skulplengte (mm), voeromsetverhouding (VOV) en spesifieke groeitempo (SGT) vir massa en lengte was egter nie betekenisvol verskillend vir enige van die behandelings nie. Geen betekenisvolle verskille is ook gevind tussen die FM en enige van die FM vervangingsdiëte nie. Resultate vir Fase B het getoon dat diere wat die ECO dieet gevoer is betekenisvol swaarder was as diere wat ander voere gevoer is. Geen betekenisvolle verskille is waargeneem vir VOV en SGT van massa en lengte nie. Finale lengte van die diere wat ECO gevoer is was langer as die van die FME1, SBME1 en SBME3 diëte. Die ECO diere het ook in betekenisvol beter kondisiefaktor vertoon as diere wat SBM, FME3 en FME123 diëte gevoer is. Geen betekenisvolle verskille in produksie parameters is opgemerk tussen die FM en SBM diëte nie en die toevoeging van ensieme het ook nie ‘n betekenisvolle invloed gehad nie. Die gevolgtrekking is dat sojaboonoliekoekmeel suksesvol aangewend kan word vir die vervanging van vismeel in perlemoen diëte.

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