Pigment Reduction in Corn Gluten Meal and Its Effects on Muscle ...

this trial was to evaluate the effect of <strong>in</strong>creas<strong>in</strong>g levels of CGM (up to 18%) on growth <strong>and</strong>pigment deposition <strong>in</strong> fillets from ra<strong>in</strong>bow trout.4.2 Materials <strong>and</strong> methods4.2.1 Fish husb<strong>and</strong>ry <strong>and</strong> experimental conditionsThis study was conducted at the Alma Aquaculture Research Station (AARS, Alma, ON,Canada). Domestic stra<strong>in</strong> of ra<strong>in</strong>bow trout, (O. mykiss) from the AARS’s stock population wereadapted to experimental conditions for two weeks prior to start the experiment. Dur<strong>in</strong>g thatperiod, fish were fed a commercial (with no pigment supplementation) trout diet (Mart<strong>in</strong> MillsInc, Elora, ON, Canada) once a day.The 7 experimental diets were r<strong>and</strong>omly assigned to each of 21 (1,500 L) fibreglass tanks(n=3). Seventy five fish (549 g fish -1 , <strong>in</strong>itial body weight) were r<strong>and</strong>omly allocated <strong>in</strong>to eachtank <strong>and</strong> kept under a 12 h light: 12 h dark photoperiod regime. Filtered well water was suppliedapproximately at a 30.5 L m<strong>in</strong> -1 rate. Water temperature was kept at 8.5 °C. This experiment wasconducted accord<strong>in</strong>g with the guidel<strong>in</strong>es stated by the Canadian Council on Animal Care(CCAC, 1984) <strong>and</strong> the University of Guelph Animal Care Committee.Fish were h<strong>and</strong>-fed twice a week to near satiation dur<strong>in</strong>g 24 weeks. Dur<strong>in</strong>g the rema<strong>in</strong><strong>in</strong>gfive days, fish were fed us<strong>in</strong>g belt feeders. Daily ration to be dispensed by belt feeders wasdeterm<strong>in</strong>ed by averag<strong>in</strong>g the amount of feed given to that tank dur<strong>in</strong>g the previous two dailyh<strong>and</strong> feed<strong>in</strong>gs.Five fish were sampled at the beg<strong>in</strong>n<strong>in</strong>g of the experiment for the determ<strong>in</strong>ation of <strong>in</strong>itialcarcass composition <strong>and</strong> another sample of five fish was used for <strong>in</strong>itial muscle pigment content<strong>and</strong> colour determ<strong>in</strong>ation. At the end of the experimental period, four <strong>and</strong> ten fish from each tank77