Project Number: 2050-21310-004-15
Start Date: Dec 01, 2013
End Date: Jun 30, 2014
The collaborative research will focus on the inclusion of innovative feed ingredients in the diets that will be formulated and produced by ARS and fed to Yellowtail by RC. The collaborative research between ARS and RC will focus on the following three key tasks: 1) Determine the effect of alternative ingredients on the extrusion process and resulting pellet quality. All diets will be manufactured by cooking extrusion. Extrusion condition including barrel temperatures, pressure at the diet head, dry material feed rate, water addition rate, and specific mechanical energy will be monitored continuously and recorded. A sample of uncoated pellets will be taken to determine Pellet Durability Index with a Holmen tester.2) Determine the digestibility and palatability of the new ingredients for Yellowtail. Both palatability and apparent digestibility of nutrients and energy and amino acid availability will be determined from one group of fish with 20 fish per tank and three tanks of fish per diet and fed compounded extruded diets. All fish will be fed by hand to satiation so that feed consumption can be precisely measured to determine if the feed ingredient affects feed intake. The methodologies employed will include standard procedures that are well established in the investigators’ laboratories. Nutrient and energy availability will be determined by comparing the amount in feces relative to the amount in the feed. Standard methods will be used to estimate apparent digestibility coefficients (ADCs) as described below. Yttrium oxide will serve as the inert marker. A complete reference diet meeting or exceeding all known nutritional requirements for rainbow trout will be blended with the test ingredients in a 70:30 ratio (dry-weight basis) to form test diets. The reference diet will be fish meal free in order to have low enough levels of phosphorus to detect availability of phosphorus in the test ingredients. This diet has been used successfully in several digestibility and growth trials with rainbow trout. 3) Determine the effect of alternative ingredients on growth and feed efficiency or Yellowtail. Once digestibility of nutrients has been determined, the test ingredient will be evaluated in a growth trial with juvenile yellowtail following standard procedures. All diets will be manufactured as described in objective 1. Diets will be formulated to meet or exceed all known nutrient requirements and contain graded levels of the test ingredient with the maximum level being determined by the specific nutrient composition of the ingredients. A commercial fish meal based diet will be fed as a reference along with a diet of known composition without the test ingredient as a control. Experimental diets with juvenile fish will be fed for 9 weeks, with the average starting weight of the yellowtail between 20 and 40 grams/fish and will be fed by hand to satiation. Gain, feed intake, feed conversion ratio, protein and energy retention and survival will be determined. A 10 fish sample will be collected at the beginning of the trials and 5 fish from each tank will sampled at the end of the trial for body compositional analysis.