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The effect of phytic acid removal on the acceptability of canola and rapeseed feedstuffs as partial and complete replacements for fish meal in salmonid diets

University of British Columbia

Two experiments were conducted with juvenile rainbow trout (Oncorhynchus mykiss) (< 5g) in ambient well water, to investigate the influence of phytic acid removal on the feeding value of rapeseed and canola protein feedstuffs used as substitutes for fish meal and other animal protein in the diets. The first investigation examined whether phytic acid removal by commercial pretreatment of rapeseed protein concentrate (RPC) with microbial phytase, with /without essential amino acid supplementation or cation-anion balancing to mimic the chemical profile of a control diet based on fish meal (which provided 59% of the dietary protein), could improve the nutritional value of RPC for trout sufficiently to allow it to replace all of the fish meal without compromising performance. Results indicated that commercial dephytinization significantly enhanced the nutritional value of RPC to the extent that, with the addition of FINNSTIM™ (1.5 % DMB; palatability enhancer), it could replace all of the fish meal without compromising performance. Essential amino acid supplementation and cation-anion balancing provided no additional nutritional benefit. The second investigation, examined whether commercial dephytinization or dephytinization by oral administration of a low dose (1,000 PU/ g dry diet) or high dose (4,000 PU/g dry diet) of microbial phytase to diets in which fish meal provided 70% of the protein and canola meal (CM) provided 20%, or animal protein-free diets in which RPC provided 95% of the protein, could enhance the nutritional value of the diets for trout. Also, the effect of fibre reduction of CM with or without the addition of a high dose of phytase was examined. Findings indicated that in diets containing 1.5% FINNSTIM™ , commercial dephytinization as well as direct application of either dose of phytase significantly improved the nutritional value of CM for trout. By contrast, direct application of either dose of phytase did not improve the nutritional value of RPC for trout. Although commercial dephytinization did improve RPC nutritional value, the enhancement was not sufficient to make the diets nutritionally equal to the control fish meal diet. Fibre reduction with or without direct phytase addition did not nutritionally improve the CM diets to levels comparable to the control diets.

Thesis/Dissertation

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2009-06-15

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http://hdl.handle.net/2429/9199

Animal Science

University of British Columbia

UBCV

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