Location: Harry K. Dupree Stuttgart National Aquaculture Research Cntr
2016 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
Studies have begun to evaluate the efficacy of feeding stimulants, i.e., palatability enhancers or “palatants” that are typically used to stimulate intake of manufactured feed in fish. As fish diets become less animal meal based and more plant-based, poor feed intake becomes a major bottleneck in the production of some fish and slows producer acceptance of plant-based feeds that are more sustainable. A series of short, 5-day palatability trials are underway with juvenile hybrid striped bass to assess feed intake of a plant-based diet supplemented with one or more palatants of interest in comparison to unsupplemented plant diets and a well-accepted commercial diet. The compounds of interest include: betaine (trimethylglycine), carboxylic acids, crawfish oil, dimethyl-B-propiothetin (DMPT)/ dimethylsulfonyl propionate (DMSP), garlic, inositol monophosphate (IMP), liver by-products, molasses, feed-grade nucleotides, poultry fat, ProOmega 55™, and shrimp oil. (Objective 1)
In collaborative work with scientists at the University of Arkansas at Pine Bluff and the Arkansas Agricultural Extension Service, we are evaluating alternative feeding strategies and diet formulas for minimizing winter kill in overwintering commercial stocks of bluegill and baitfish in Arkansas. Demand for different varieties of bluegill has moved beyond sport fisheries or natural stock enhancement to food fish markets. The U.S. baitfish industry, which is centered in Arkansas, dwarfs U.S. food fish production in terms of economic impacts of this sector of U.S. agricultural. Winter fish mortality is a phenomenon that has been widely cited by fish farmers in temperate regions of the U.S. as a major factor that decreases profitability and sustainability. When water temperatures become colder during the winter months, lipid stores are often utilized as an energy source during a period when feeding is also reduced. In phase I of this work we are evaluating the effects of once a month, once a week, and twice a week feeding during winter on survival, growth, and fatty acid profiles of the various species of interest. In phase II, we will evaluate the efficacy of ideal protein diets of varying protein to energy ratio when fed pre-winter or during winter for alleviating winter kill in bluegill. (Objective 1)
ARS researchers feel that white bass (WB) may be a valuable domestic food-fish, yet are under-represented in U.S. aquaculture. There is extremely limited data on nutritional requirements of this fish, and on use of different culture methods that might optimize production and improve farm diversity and profitability. Cage culture allows for the growing of fish in ponds that may otherwise be difficult to harvest, either due to irregularly-shaped pond bottoms, shape of the pond, or presence of debris and obstacles on the pond bottom. To investigate whether white bass can be grown in cages with acceptable growth rates and high (>85%) percentage survival, a study was started in May 2016 to determine the effects of different stocking densities on growth, body composition, and fillet proximate composition. The culture trial is being conducted in 12 cages (3.5 m3; 1.2 x 2.4 x 1.2 m). White bass juvenile (60 g) were stocked into nylon-mesh floating cages at four different rates (100, 200, 300, and 400 fish/cage) and are being fed a commercial diet that meets all known nutrient requirements for bass. There are three replicates per stocking rate and the study is ongoing. (Objective 1)
ARS researchers collected wild white bass broodstock from the Nueces River, TX. Tissues have been collected for genotyping at Auburn University. We successfully produced 103 experimental crosses from amongst each of the five wild white bass strains and the domestic white bass strain resulting in over 650,000 fry. The resulting fry are being raised in preparation for inclusion in Fall 2016 production performance trials. Broodfish are currently being conditioned for the next phase of the plan in FY17. (Objective 2)
The outdoor biofloc technology production (BFT) 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. (Objective 3)
Farmers in the U.S. have adopted the direct-stock production method for hybrid striped bass (HSB) that relies on stocking a 0.5-1.5-ounce advanced fingerling for which production practices have not been optimized. ARS researchers completed in October a range-finding experiment to quantify the relationship between fingerling hybrid striped bass growth and yield, and stocking rate in the outdoor BFT production system. Survival was high across stocking rates, averaging 80%. A certain percentage of the HSB fingerling population gains an early growth advantage and becomes cannibalistic towards conspecifics. “Cannibals” were present, but decreased linearly from 33% to 6% of the population as stocking rate increased. Target size fish at all stocking rates averaged 0.5 ounce each. This study was the first to demonstrate that hybrid striped bass can be grown successfully in the biofloc technology production system. Increasing the stocking rate further to eliminate the presence of cannibals is planned. (Objectve 3)
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 BFT production system. Food-size tilapia have been grown successfully in a BFT production systems that were stocked with large (2.5-7.0 ounce) fingerlings, but using this 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 an inefficient use of production inputs, but is practiced by many farmers. ARS researchers completed a range-finding experiment to quantify the relationship between fingerling tilapia growth and yield, and stocking rate in the outdoor BFT production system. Tilapia yields ranged from 1.2-2.3 lb per cubic foot of water and were 3-4 times greater than yields obtained when channel catfish were reared in the BFT system. Tilapia growth at the higher stocking rates (and biomasses) was less than optimal because the aeration system was unable to maintain dissolved oxygen concentration optimal for growth. An improved aeration system was designed and installed during the winter. Data analysis is on-going. We initiated in mid-June a follow-on stocking rate-yield study to repeat and extend the upper range of stocking rates for hybrid tilapia. Fish will be grown until October. Results of these two studies should demonstrate the optimal stocking rate to produce an advanced fingerling. (Objective 3)
Tilapia grown in the BFT production system are able to derive nutrition by consuming the biofloc and because of this some researchers advocate lowering the protein content of formulated rations. However, the optimal protein content has not been determined for tilapia in BFT production. ARS researchers initiated a study in mid-May to quantify the relationship between formulated diet protein content and tilapia growth (to a 1-lb market size) and yield, and water quality in an outdoor BFT production system. We used the ratios and levels of essential amino acids in tilapia muscle, i.e., the ideal protein model we chose, as the targets for optimizing diet formulations. Diets were formulated using the digestible, as opposed to total, nutrient levels found in the feed ingredients and supplemented with limiting essential amino acids to meet the target levels suggested by the muscle profile. Fish will be grown until October. (Objective 3)
Accomplishments
1. Utilization of distiller’s dried grains with solubles (DDGS) as a potential replacement for fish meal in tilapia diets. Tilapia has become the most-produced food-fish in the world for the global marketplace in 2015. There are several important reasons for this dramatic increase in production, one being its acceptance of diets containing plant-protein ingredients. However, as production has increased, prices paid to producers have decreased. As feed costs represent approximately 35-55% of variable costs to tilapia producers, formulating nutritious, but less expensive diets may assist producers in maintaining profitability. Historically, distiller’s dried grains with solubles (DDGS), was by-product of the distillery industry. Ethanol production in the United States has undergone significant expansion within the last 10 years as a result of rising energy costs and mandates for biofuel use in the U.S. Energy Acts of 2005 and 2007. Increased ethanol production has subsequently led to increased production of DDGS, and production in the U.S. has almost quadrupled since 2005. With the abundance of DDGS in the U.S., it has been proposed as a protein source for use in aquaculture diets due its relative low cost per unit protein basis, and absence of anti-nutritional factors found in other plant-based ingredients. We demonstrated that a substantial amount of the fish meal in typical tilapia fry diets can be replaced with DDGS, when combined with poultry by-product meal and supplemental amino acids (methionine and lysine). Growth of tilapia fed the diets containing DDGS was slightly less than fish fed the fish meal diet, but average fish growth was high regardless of which diet was fed. DDGS replacement of fish meal in tilapia diets can be substantial when diets are carefully formulated. This will result in less expensive diets for tilapia, particularly hatchery, the stage of fish which use diets with high percentages of fish meal.
2. Fish meal in hybrid striped bass diets can be replaced with high-protein, low-antigen soy varieties. Nutrient digestibility studies conducted in hybrid striped bass (HSB) in 2015 on three novel varieties of non-GMO soybeans were followed by growth studies in HSB in 2016. These soy varieties contain higher protein and lower anti-nutritional factors than traditional soybean and were used to replace all the fish meal in a typical commercial hybrid striped bass feed. Performance of HSB, e.g., growth, body composition, intestinal health, immunological response to soy antigens, and resistance to disease, were assessed in fish when fed diets with or without fish meal replacement. Results of this collaborative effort (University of Arkansas (UA) at Pine Bluff, UA at Fayetteville, ARS Trout-Grains Project, Hagerman, ID, and US Fish and Wildlife Service Fish Technology Center, Bozeman, MT) were presented to the scientific and trade community at the 2016 Aquaculture America Conference and indicate fish meal can be totally replaced by high-protein, low antigen soybean meals in hybrid striped bass diets when formulated on an available amino acid basis and supplemented with limiting amino acids. Moreover, we found little evidence to suggest that hybrid striped bass are as sensitive as some fish to soy-derived antigens found in traditional soy varieties.
3. Tilapia whole-body amino acid profile is a robust nutrient target for optimizing commercial tilapia diets. ARS researchers evaluated 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 current commercial diets typically containing fish meal. This collaborative work with Kentucky State University was 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. Results showed that the more the diet nutrient profile diverged from the nutrient profile of whole body tilapia, the poorer the diet performance was. 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.
4. Taurine supplementation not needed to support growth of hybrid striped bass fed all-plant-protein diets. ARS researchers determined the effectiveness of supplementing the amino acid taurine (Tau) for supporting growth of hybrid striped bass fed all-plant-protein diets. Tau is often conditionally limiting in some species of fish fed plant protein diets which are low in Tau. The plant-based diets were formulated with graded levels of taurine at 0, 0.5, 1, 2 and 4% of diet. These levels were chosen to bracket those found effective in multiple fish species, and included one excessive level (4%). At the end of the trial we found no evidence that Tau is required by HSB fed all-plant protein diets. At the same time, muscle saturation and liver data suggest there is some benefit to low dietary inclusion levels (< 1%) of Tau to maximize body stores, especially since taurine is a relatively inexpensive feed additive. This collaborative work with the U.S. Fish and Wildlife Service Fish Technology Center and Texas A&M University establishes the relative effectiveness of taurine in HSB and two other carnivorous aquaculture species (trout and red drum) fed plant-based diets and are critical to industry and science for commercial feed formulation and research.
5. Insect meal is a viable protein ingredient for white shrimp diets. Over 90% of farmed shrimp rely on high protein diets containing high percentages of marine fish meal. Future growth and profitability within the shrimp aquaculture sector is dependent upon continued improvements in diet efficiency and formulation; specifically a reduction in fish meal. A potential candidate ingredient for fish meal replacement is the black soldier fly (Hermetia illucens) which has been evaluated as a possible organism to use in bioconversion of manure and food compost to reduce waste residue and has received a great deal of interest for use as a protein source in other animal industries. In collaboration with Kentucky State University, six test diets containing graded levels of black soldier fly larvae meal (7%, 14%, 21%, 28%, and 36% of diet) as replacements for protein from menhaden FM were fed to juvenile shrimp and compared to shrimp fed a control diet formulated similar to a commercial shrimp diet containing 25% menhaden FM and 23% soybean meal. Shrimp fed the control diet with the highest percentage of fish meal had the highest weight gains compared to all other diets. However, reasonable growth, up to 95% to 100% of the maximum final weight, weight gain, specific growth rate, and food conversion, could be obtained if replacement of fish meal by black soldier fly larvae meal was limited to less than 25% of the diet. However, the research also revealed that addition of limiting amino acids to the replacement diets could significantly improve shrimp growth when fed diets with higher percentages of this insect meal. Insect meal also has the potential of being reared on organic substrates thus expanding opportunities for organic aquaculture.
None.
Review Publications
Koch, J.F., Rawles, S.D., Webster, C.D., Cummins, V., Kobayashi, Y., Thompson, K.R., Gannam, A.L., Twibell, R.G., Hyde, N.M. 2015. Optimizing fish meal-free commercial diets for Nile Tilapia, Oreochromis niloticus. Aquaculture. 452:357-366.
Green, B.W., Engle, C., Lochmann, R., Phillips, H. 2016. Low-intensity, stocker-based channel catfish culture. North American Journal of Aquaculture. 78:125-135.
