1a. Objectives (from AD-416):
A feeding study will be conducted to measure growth performance of juvenile Atlantic salmon fed five experimental diets formulated with different corn protein concentrates (one control and four test diets). Measurements will include initial weight, final weight, feed intake, flesh color, and fillet yield. The study will also measure protein, energy, organic matter, dry matter, and amino acid digestibility of the experimental diets (one control and four test diets).
1b. Approach (from AD-416):
Experimental diets will be formulated to satisfy the nutritional requirements of Atlantic salmon. Eighteen ~0.20 m3 tanks filled with seawater will be stocked with a total of 288 Atlantic salmon (Salar salmo) smolts (80-100 grams) (18 fish/tank) at the USDA ARS National Cold Water Marine Aquaculture Center in Franklin, ME. Fish will be fed the test diets for a 1 week acclimation period prior to the start of the proposed 16 week experimental diet study. Diets will be fed to three replicate tanks for the control and corn gluten diets and fed to four replicate tanks for the remaining test diets. All of the diets will be produced at the Fish Technology Center in Bozeman, MT using commercial manufacturing methods. Natural photoperiod will be maintained during the study. Fish will be fed using automatic feeders such that feed is supplied at 100% of maximum expected intake. Each tank will also be hand fed to satiation once daily to insure that fish are being fed to apparent satiation once daily with minimal waste feed. Fish in each tank will be bulk-weighed and counted every four weeks during trial with a summary provided to collaborator at 4 week intervals. Monthly progress reports will be provided along with a final report summarizing average fish weight gain, feed intake, feed conversion ratio, fillet color and fillet yield. Statistical analyses will be conducted to determine if significant differences exist between diets. A digestibility study will be conducted at the termination of the growth trial using ~500 g Atlantic salmon at the USDA ARS National Cold Water Marine Aquaculture Center in Franklin, ME. Fish from the growth study will be maintained in the same replicate tanks in the growth study and supplied with 4-L min-1 of oxygen saturated water at a temperature of 13°C to14°C from a recirculating biological filtration system. The fish will be manually stripped of feces and the feces from each tank pooled until enough dried feces is obtained to weigh 5g. The feces and diets will then be analyzed for ash, moisture, crude lipid content, crude protein content and amino acid content. Yttrium oxide will serve as the inert maker. Apparent digestibility coefficients of each nutrient in each diet will be calculated according to the following equation.
3. Progress Report:
The feeding trial for growth and digestibility consisted of 5 diets different corn protein products fed to salmon juveniles from the USDA ARS National Cold Water Marine Aquaculture Center’s breeding program. Eighteen ~0.26 m3 tanks were stocked with a total of 288 Atlantic salmon juveniles. Fish were fed the test diets for a 1 week acclimation period prior to the start of the proposed 16 week experimental diet study. Fish in each tank were bulk-weighed and counted every four weeks during trial with specific growth rate, feed conversion ratio, average weight, average weight gain, percent increase calculated at the final weighing. A macronutrient and lysine digestibility study was conducted at the termination of the growth trial using ~600 g Atlantic salmon. The fish were manually stripped of feces and the feces from each tank pooled until enough dried feces was obtained. The feces and diets were analyzed for ash, moisture, crude lipid content, crude protein content and lysine content. The performance of Atlantic salmon fed the reference or experimental diets did not vary over the 16-week feeding trial. Results showed the inclusion of 15% corn protein products in the diet did not affect the growth performance, nutrient digestibility or proximate composition of Atlantic salmon compared to salmon fed a fishmeal reference diet. Apparent digestibility values for lysine and macronutrients and proximate composition were all similar to the fishmeal reference diet.