Location: Harry K. Dupree Stuttgart National Aquaculture Research Cntr
2015 Annual Report
Objectives
Objective 1: Develop novel ingredients and formulate diets for warmwater finfish. Novel ingredients and new formulations will target reduced reliance on fishmeal in the diets, enhanced nutrient delivery (e.g., better amino acid availability), and reduced anti-nutritional factors.
Sub-objective 1A: Develop and validate practical all-plant protein diets for hybrid striped bass (HSB) and white bass.
Sub-objective 1B: Determine optimal inclusion level of distiller’s dried grains with solubles and high-protein distillers dried grains with solubles in diets for Nile tilapia.
Sub-objective 1C: Determine optimal inclusion level of cottonseed meal and poultry by-product meal in diets for largemouth bass.
Objective 2: Obtain and test white bass broodfish from multiple populations for improved production of hybrid striped bass. Key phenotypic traits will be defined and a white bass broodstock will be established.
Sub-objective 2A: Obtain and produce white bass from multiple geographically distinct populations.
Sub-objective 2B: Conduct white bass strain performance evaluation and selection.
Sub-objective 2C: Hybrid striped bass performance evaluation.
Objective 3: Compare and optimize production of hybrid striped bass in biofloc technology and pond production systems.
Sub-objective 3A: Define stocking rate/initial biomass – yield relationship for HSB in a biofloc technology system.
Sub-objective 3B: Compare production of HSB in biofloc technology and pond production systems.
Approach
Identify promising feed palatants that enhance all plant protein (APP) diet feed intake; identify plant proteins for use in APP test diets; formulate a series of marine fish meal (FM) replacement diets using ideal protein theory, plant protein blends, and feed additives designed to ameliorate ingredient deficiencies; characterize growth performance, nutrient retention, gut microflora, and metabolic gene expression in response to FM replacement diet; and validate promising APP diets in a pond production trial. Feeding studies will evaluate the effect of partial or total replacement of FM by either Distiller’s dried grains with solubles or high protein Distiller’s dried grains with solubles in the diet of Nile tilapia on feed intake, growth, feed conversion, and histology of the intestine. A feeding study will evaluate the effect of substitution of FM by various ratios of poultry by-product meal and cottonseed meal in practical diets for juvenile largemouth bass on growth performance, health status, and body composition. Adult white bass (WB) will be acquired from three distinct regions of the species’ native range (Arkansas River, AR, Central and South TX, and Upper Tennessee River, TN), spawned and the genetic diversity and production performance of multiple strains and families will be compared in tanks and ponds to our domesticated WB broodfish population in order to select superior performing families to use in developing improved synthetic lines. Evaluate production performance of families of hybrid striped bass (HSB) made from the WB improved synthetic lines. Quantify the relationship between the HSB stocking rate/initial biomass – yield relationship to produce advanced fingerlings in the biofloc technology production system and compare to traditional pond production method.
Progress Report
Three novel varieties of non-GMO soybeans developed at the University of Arkansas contain higher than typical levels of protein and lower levels of antinutritional factors that cause problems in feed digestion, growth, and health in fish. The novel soybeans were processed into meals, thoroughly characterized for chemical and nutrient properties, then incorporated in test feeds fed to hybrid striped bass. The resulting fish excrement was collected and analyzed to determine the availability of essential nutrients in the soy ingredients to hybrid striped bass (HSB). Several differences in nutrient digestibility were noted among the different soy varieties. The final step, currently underway, is comparing fish performance (growth, composition of growth, intestinal health and resistance to disease) when all the fish meal typically used in HSB diets is replaced with the soybean varieties of interest. This work is aimed at evaluating the nutritional value of plant proteins as replacements for fish meal in hybrid striped bass diets, and is a collaborative effort involving the University of Arkansas (UA) at Pine Bluff and UA-Fayetteville, the ARS Trout-Grains Project, Hagerman, Idaho, and the U.S. Fish and Wildlife Service Feed Technology Center, Bozeman, Montana.
ARS scientists are currently evaluating the use of the tilapia whole body amino acid profile as a nutrient target for optimizing commercial tilapia diets instead of using the nutrient profile of the current commercial diets that typically contain fish meal. This collaborative work with Kentucky State University is aimed at formulating and testing alternative diets for warmwater fish. Fish meal in the commercial diet was completely replaced with different ratios of poultry by-product meal (PBM) and soybean meal (SBM). Amino acids were supplemented in the PBM-SBM diets to match the levels measured in the original commercial (with fish meal) diet. At first glance fish performance appeared optimum when fish meal in the diet was replaced with a 50:50 mix of PBM and SBM. Upon further analysis, however, it appears that the more the diet nutrient profile diverges from the nutrient profile of whole body tilapia, the poorer the diet performance is. This work is a critical discovery in developing diet formulas for testing combinations of novel alternative ingredients for replacing fish meal in commercial diets for tilapia.
ARS scientists are currently determining the effectiveness of taurine supplementation for enhancing the growth of hybrid striped bass fed all-plant-protein diets. Taurine has been reported to be efficacious in supporting growth of some fish species, particularly when supplemented to all-plant-protein diets. However, the benefit of taurine supplementation to HSB has yet to be demonstrated. The plant-based test diets were formulated with graded levels of taurine at 0, 0.5, 1, 2 and 4% of diet. These levels were chosen to bracket the estimated effective levels of taurine found in multiple fish species, and included one level (4%) in excess of those levels. Preliminary results suggest that dietary taurine supplementation does not enhance hybrid striped bass growth on plant-based diets. Currently, the taurine concentrations in fillets from fish fed the different diet levels of taurine are being measured in collaboration with the USFWS and Texas A&M University. The final results should establish the relative effectiveness of taurine in HSB and two other carnivorous aquaculture species (trout and red drum) fed plant-based diets. These data are critical to industry and science for commercial feed formulation and research.
Researchers collected wild white bass broodstock from the Upper Ouachita River, AR, Little Missouri River, AR, Tallapoosa River, AL, and the Nueces River, TX. Tissues have been collected for genotyping at Auburn University, and all fish are currently being conditioned for the next phase of the plan in FY16.
The outdoor biofloc technology production system is a novel, intensive production system in which high stocking and feeding rates are possible, and fish yields can be obtained that are many times greater than yields from traditional earthen pond culture. Such yields are possible because unassimilated feed nitrogen, which is excreted by fish as ammonia, is utilized by the phytoplankton and bacteria present in the system. Continuous aeration with diffused air supplies the required dissolved oxygen and maintains the phytoplankton and bacteria in constant suspension in the water column. Scientists completed in October a study that compared using “mature” water with high or low concentration of total suspended solids that was carried over the winter from the previous year’s experiment to starting the production system with “new” water at the beginning of the growing season. The objective was to determine the effect of water type on system water quality dynamics, growth and yield of channel catfish, and incidence of common microbially derived off-flavors. Data analysis is underway.
ARS scientists designed and constructed nine 8-foot diameter outdoor tanks for use in hybrid striped bass biofloc technology production system experiments. Each research tank is aerated continuously with diffused air, and dissolved oxygen and water temperature are monitored continuously by datalogger.
Farmers in the U.S. have adopted the direct-stock production method for hybrid striped bass that relies on stocking an 0.5-1.5-ounce advanced fingerling for which production practices have not been optimized. ARS scientists initiated a range-finding experiment to quantify the relationship between fingerling hybrid striped bass growth and yield, and stocking rate in the outdoor biofloc technology production system. Fish were stocked in early July into 8-foot diameter tanks at 4.6-23.2 fish per square foot of water surface area and will be grown until late October.
Tilapia aquaculture is expanding in the southern-most regions of the U.S. and the production systems used by farmers have not been optimized. Additionally, fish farmers at sub-tropical latitudes can produce a crop of tilapia during the May-October growing season. It is likely that outdoor tilapia production systems used by U.S. farmers can be intensified and made more efficient by using the biofloc technology production system. Food-size tilapia have been grown successfully in a biofloc production systems that were stocked with large (2.5-7.0 ounce) fingerlings, but using the biofloc system to produce these large fingerlings has not been investigated. Hatchery-reared tilapia, which is the sole source available to U.S. farmers, weigh about 0.2 ounces when purchased by the farmer. Stocking these small fingerlings into food fish production units is inefficient, but is practiced by many farmers. Researchers initiated a range-finding experiment to quantify the relationship between fingerling tilapia growth and yield, and stocking rate in the outdoor biofloc technology production system. Fish were stocked in mid-May into 200 square-foot outdoor tanks at 4.6-23.2 fish per square foot of water surface area and will be grown until October.
Accomplishments
