|Rawles, Steven - Steve|
|Koch, Joao - UNIVERSIDADE ESTADUAL PAULISTA (UNESP)|
|Thompson, Kenneth - KENTUCKY STATE UNIVERSITY|
|Gannam, Ann - U.S. FISH AND WILDLIFE SERVICE|
|Twibell, Ronald - U.S. FISH AND WILDLIFE SERVICE|
Submitted to: Aquaculture Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2015
Publication Date: 5/16/2015
Citation: Webster, C.D., Rawles, S.D., Koch, J., Thompson, K.R., Gannam, A.L., Twibell, R.G. 2015. Bio-ag reutilization of distiller’s dried grains with solubles (DDGS) as a substrate for black soldier fly larvae, Hermetia illucens, along with poultry by-product meal and soybean meal, as total replacement of fish meal in Bio-ag reutilization of distiller’s dried grains with solubles (DDGS) as a substrate for black soldier fly larvae, Hermetia illucens, along with poultry by-product meal and soybean meal, as total replacement of fish meal in diets for Nile tilapia, Oreochromis niloticus. Aquaculture Nutrition. 22:976-988.
Interpretive Summary: Nile tilapia is a tropical fish endemic to freshwaters in Jordan, Israel, and parts of Africa. Because of their rapid growth rates, good quality flesh, disease resistance, adaptability to a wide range of environmental conditions, ability to grow and reproduce in captivity and to feed at low trophic levels, tilapia have become an excellent choice for aquaculture. Since tilapia are primarily produced in intensive production systems, it has become necessary to evaluate practical diets that are economically and environmentally sustainable, as well as nutritionally-complete. Fish meal (FM) has customarily been used as a major animal protein source in aquaculture diets, and the main source of protein in diets for tilapia fry and juveniles. However, FM is the most-expensive macro-ingredient ($US1100-$1400 per ton) and is also highly desired in the diets of other livestock industries. Thus, special attention must be given to tilapia nutrition with emphasis on replacement of FM by less expensive vegetable and animal protein sources. One agricultural by-product that can be used as a protein source for aquaculture diets is distiller’s dried grains with solubles (DDGS). DDGS has been proposed as a protein source for aquaculture diets due its relatively low cost per unit protein, absence of anti-nutritional factors found in other plant-based ingredients, and increasing availability. Ethanol production in the United States, for example, 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 in the U.S, where production has more than tripled since 2005 from 10.4 million metric tons (mmt) to an estimated 39.0 mmt for 2014. While there have been several studies conducted to evaluate the use of DDGS in Nile tilapia diets, all reports used fish meal (FM) in the diets. No studies have been conducted to evaluate the secondary use of DDGS in diets for an aquaculture species after it has served as a source of nutrients for its primary purpose (bio-ag-reutilization), and there are limited published data on the use of DDGS, in combination with an animal source protein, as total replacement of FM in diets for juvenile Nile tilapia. Hence, a feeding trial was conducted to evaluate growth and body composition of Nile tilapia when fed diets without FM, with and without supplemental methionine and lysine, and with and without a commercial enzyme product. A feeding trial was conducted in which juvenile Nile tilapia (3 g) were fed different diets containing a mixture of two protein ingredients (distiller’s dried grains with solubles and poultry by-product meal, PBM) as total replacement of menhaden fish meal. Fish were fed all they could eat on one of seven diets which contained the same amount of protein (35%) and energy for 6 weeks. Diet 1 was formulated to be similar to a commercial, high-quality, tilapia diet containing 20% FM. Diets 2-7 were formulated to contain a high percentage (45%) of DDGS and PBM (25%) with various amino acids added to simulate the control diet. After six weeks, growth of tilapia fed the diets containing DDGS were slightly less than fish fed the control (FM) diet, and fish did not utilize the diets containing DDGS quite as efficiently as tilapia fed the FM diet; however, average weight gains in all dietary treatments were high, ranging from 1533% to over 2000% of initial weight. These data suggest that all diets were well utilized and that refinements in amino acid supplementation levels may yield narrower margins in performance between DDGS-based, as opposed to fishmeal-based, diets for juvenile tilapia. Whole-body proximate composition was not different among treatments and amino acid profiles of fish fed DDGS diets were
Technical Abstract: A feeding trial was conducted in a closed system with Nile tilapia, Oreochromis niloticus, juveniles (mean initial weight, 2.66 g) to examine total replacement of menhaden fish meal (FM) with distiller’s dried grains with solubles (DDGS), which had been used as substrate for the production of black soldier fly larvae, Hermetia illucens, in combination with soybean meal (SBM) and poultry by-product meal (PBM), with or without supplementation of the amino acids (AA) DL-methionine (Met), L-lysine (Lys) and a commercial non-amylaceous polysaccharide enzyme (Enz) product. Fish were fed seven isoenergetic (available energy [AE] = 4.0 kcal/g of diet) and isonitrogenous (35% protein as fed basis) practical diets formulated with equivalent digestible protein levels. Diet 1 was formulated to be similar to a commercial, high-quality, tilapia diet containing 20% FM. Diets 2-5 were formulated as a 2 x 2 factorial to replace FM with similar contributions from DDGS (45%), PBM (25%), and SBM (2.1 – 2.9%), but to differ in supplementation of AA and/or Enz preparation. Diets 6 and 7 were formulated to investigate the effects of a 2/3 and 1/3 reduction, respectively, in DDGS contribution to the replacement protein mix, with concomitant increases in SBM, with respect to diet 3, and were balanced with Lys and Met. After six weeks, growth responses were slightly attenuated (P = 0.05) and average daily intake (ADI) and feed conversion ratio (FCR) were slightly higher in tilapia fed DDGS diets 2-5 compared to those of fish fed the FM control diet 1. Growth responses were not significantly affected by the presence or absence of AA or Enz (diets 2-5), or the level of DDGS (diets 3, 7, and 6). Whole-body proximate composition was not different among treatments. Amino acid profiles of fish fed DDGS diets were not significantly different from those of fish fed the FM control. Evidence of interaction between AA and Enz supplementation was detected in whole-body amino acid concentrations such that AA content was higher with AA or Enz addition alone, but lower when both were added to the diet. Results suggest that DDGS replacement of FM in tilapia diets can be substantial when diets are formulated on a digestible protein basis and DDGS is combined with highly digestible animal (PBM) and plant proteins (SBM).