Abstract
A comparative feeding trial and digestibility determination were conducted to evaluate the nutritional value of a commercial, high-protein distiller’s dried grains with solubles (HP-DDGS) ingredient in the diet of Nile tilapia (Oreochromis niloticus). For the feeding trial, six diets were formulated to contain 360 g total dietary protein kg-1 and were prepared with incremental levels of protein from the HP-DDGS (0, 75, 150, 225, 300, and 375 g of dietary protein kg-1) replacing protein from fishmeal and soybean meal. Juvenile tilapia ( 10.4 g ± 0.37 ; average initial weight ± SD ) were evenly distributed in 24, 38-L aquaria operated as a recirculating system and fed twice daily to apparent satiation throughout the 8-week trial. Nile tilapia exhibited no significant ( P > 0.05 ) differences in weight gain, feed efficiency, condition indices, whole-body proximate composition, or innate immunological responses when fed any DDGS-supplemented diets compared to the control diet. Percent apparent digestibility coefficients (ADCs) of the DDGS product for organic matter, crude protein, and gross energy were 74.8%, 83%, and 82.8%, respectively. Availability values for all amino acids were 89% or greater. Thus, this high-protein DDGS was established as a readily digestible protein feedstuff suitable for replacing soybean meal and fishmeal at up to 375 g of total dietary protein kg-1 in a practical diet for Nile tilapia.
Highlights
Aquaculture has reached an all-time peak, supplying over 100 million of the world’s 180 million tons of fish and aquatic products for human consumption as of 2018, and aquacultural production is likely to continue expanding due to the demand of a growing human population and largely static harvest from capture fisheries [1,2,3]
No significant (P > 0:05) differences were identified for evaluated condition indices (HSI, intraperitoneal fat (IPF) ratio, and muscle yield) as these parameters did not exhibit significance in either linear or quadratic regression models (Table 4)
Prior studies have evaluated the efficacy of dietary supplementation of both types of ingredients in the diets of freshwater omnivorous species such as Nile tilapia [32, 33] and channel catfish (Ictalurus punctatus) [19], as well as strictly carnivorous freshwater species, such as the hybrid striped bass (Morone chrysops X M. saxitilis) [34] and rainbow trout (Oncorhynchus mykiss) [35]
Summary
Aquaculture has reached an all-time peak, supplying over 100 million of the world’s 180 million tons of fish and aquatic products for human consumption as of 2018, and aquacultural production is likely to continue expanding due to the demand of a growing human population and largely static harvest from capture fisheries [1,2,3]. The aquaculture sector is the fastest growing food production industry and has experienced an average growth rate of 5.8% from 2000-2016 [3] furthering the economic strain placed on providing valuable feed resources to support intensive fish production (e.g., fishmeal and fish oil) [4]. To meet this challenge, the aquaculture industry has invested in evaluating fishmeal and fish oil replacements to alleviate unprecedented demand for those resources and allow for continued growth to meet the goal of providing cost-effective seafood for the global population. Researchers are mindful of potential antinutritional factors in some plant feedstuffs that may negatively affect the health of cultured organisms, such as trypsin inhibitors in soybean meal [7] and gossypol concentrations in cottonseed meal [8]
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