Project Number: 2050-21310-006-010-I
Project Type: Interagency Reimbursable Agreement
Start Date: Oct 1, 2019
End Date: Aug 31, 2022
The proposed research supports the ARS mission of conducting research to improve nutrition, sustainability, and environmental compatibility of aquaculture. For this project, we will work toward improving solid and dissolved waste management with the long-term goal of further replacing FM with PP sources while reducing their impact on water quality in the U.S. rainbow trout industry. For this two-year period, we will address this goal with the following objectives: Objective #1: To improve solid waste management by increasing fecal stability and reducing fines produced by rainbow trout through diet formulation/processing. Objective #2: To reduce dissolved waste output (primarily, ammonia and phosphorus) using highly digestible, low(er) protein and phosphorus formulations. Objective #3: To develop and test improved feed formulations using findings from 1) and 2) in a fish farm against a commercial diet.
This project will focus on two main approaches: improving solid waste management and reducing dissolved waste excretion by fish through improvements in formulation and processing of plant-based feeds. Feces recovery and particle size will be used as an indicator for feces stability. A higher recovery and a larger particle size show that the feces particles are firmer and disintegrate less easily by physical force (e.g., water flow) compared to low recovery. Ammonium is a by-product of protein catabolism. The utilization of enzymes to improve the digestibility to protein will reduce nitrogen discharge in feces as well as reduce ammonia loads due to bacterial degradation feces. Phosphorous digestibility, retention, and concentration in water are measures for P efficiency. Nutrient balance by formulation can indicate how much the nutritional strategy can reduce nutrient discharge to aquatic environment. Nutrient balances for N and P deliver a transparent picture of retention and fecal and non-fecal loss originating from the fish. We will accomplish these goals through a series of six feeding trials examining: 1) The impact of dietary starch level and gelatinization ratio on fecal characteristics and particle size distribution in rainbow trout, 2) The influence of dietary protease and cellulase enzyme supplementation on total waste production and fecal particle size distribution, 3) Binder addition to improve feces stability in a plant-based feed, 4) Low protein diet for rainbow trout to reduce ammonia output, 5) Improving phosphorous availability in rainbow trout through the use of phytase enzyme treatment of feed, and 6) on-farm trial, where the data collected in the first five trials is used to formulate a “best-feed” that will be tested in raceways under commercial trout growing conditions.