Evaluation of a Commercial High-Protein Distiller’s Dried Grain with Solubles (HP-DDGS) Product in the Diet of Juvenile Nile Tilapia (Oreochromis niloticus)

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 ( $10.4\text{g}\pm 0.37$ ; $\text{average}\text{initial}\text{weight}\pm \text{SD}$ ) 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.