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UBC Theses and Dissertations

Feed attractants for juvenile chinook salmon (Oncorhynchus tshawytscha) prepared from hydrolysates of Pacific hake (Merluccius productus) Ho, Thomas


The incorporation of soybean meal in aquaculture diets can lower feed ingredient costs, but also produces organoleptically unfavorable conditions for several salmon species. Addition of feed attractants could mask the undesirable tastes associated with soybean meal, enhance palatability of the diet, and increase feed intake. The objective of this study was to assess the feasibility of utilizing hydrolysates from Pacific hake as feed attractants in the diet of juvenile Chinook salmon. A 5-week palatability feeding trial was conducted to assess hydrolysates produced by Alcalase or Flavorzyme proteolysis of Pacific hake, compared to commercial feed attractants (krill meal and screen 1 & 2), as feed attractants in diets containing 20% soybean meal. These were compared with diets having no added feed attractants (negative control) and no soybean meal (positive control). All of the fish fed the soy-based diets had significantly (p<0.05) lower growth parameters when compared with fish fed the fishmeal based positive control diet. However, addition of Alcalase hydrolysate, krill or screen 1 provided increases in fish weight gain, feed efficiency ratio, and specific growth rate (p<0.05) compared with fish fed the negative control soy-based diet. The percent of feed dispensed that was not consumed by the fish was lowered (p<0.05) with the use of these three aforementioned attractants when compared to fish fed the negative control diet. Increased daily and total feed intake were also observed for the fish fed the Screen 1 coated diets (p<0.05). Fish fed Alcalase or Flavorzyme hydrolysate containing diets were tested for the presence of Kudoa spores, which were not detected in any of the fish tested. This study demonstrated the potential for Pacific hake, an underused marine source, to be converted to a feed attractant to help minimize the problems associated with dietary use of soybean meal in salmon aquaculture.

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