As global and domestic aquaculture production continues to increase, identifying and evaluating alternative protein and lipid sources continue to be high priorities for feed manufacturers. Brewery by-products, such as spent grain material, represent a potential source of nutrition. Notably, craft breweries which have increased in popularity and production volumes over the last decade, represent a potentially unique source. While most individual craft breweries may not produce enough by-product material to be of interest to commercial scale utilization, the combination of brewery by-product between breweries or within regions may represent a significant volume of ingredient if their nutritional profiles are similar and acceptable.
This project was undertaken to evaluate the nutritional profile, digestibility, and tolerance of craft brewery spent grains as a potential feed ingredient for red drum. The South Carolina Department of Natural Resources has partnered with Tradesman Brewing Company, Holy City Brewing, and Low Tide Brewing to collect monthly samples from each brewery over the course of a year to evaluate if and how the gross nutritional profile of spent grains changes over time and between breweries. Proximate composition (Figure 1), amino acid profile, fatty acid profile, and Nuclear Magnetic Resonance (NMR) metabolomics (Figure 2) have all been employed in developing the nutritional profiles. Additionally, digestibility diets have been formulated for each individual brewery’s material and a digestibility trial has been conducted.