when amino acid and taurinewere supplemented as fish meal declined.
NuPro™ also has shown promise when fed to tilapia, an omnivorous
fish, by replacing all of the dietary fish meal without affecting growth
(Craig and McLean, 2005).
Grain distillers dried yeast (GDDY) is a single-cell protein source
produced as a by-product of the renewable fuel industry. Grain distillers
dried yeast is a co-product from the wet mill fermentation of ethanol
fromcorn. It is the yeast fraction suspended in the distilled fermentation
media and separated fromcorn glutenmeal. The protein and amino acid
content make it conducive to inclusion in high protein aquafeeds and
potentially as a partial replacement for the protein and amino acids
from fish meals (Table 1). Recently, GDDY was examined for its potential
to replace fish meal in sunshine bass, Morone chrysops × Morone
saxatilis, diets (Gause and Trushenski, 2011a,b). During a 45-day feeding
trial, Gause and Trushenski (2011a) suggested that GDDY could replace
up to 75% of the protein provided by fish meal in the control diet of 30%
menhaden fish meal without having a negative impact on growth rate
and FCR. During a 63-day feeding trial, these authors also found that reducing
fish meal to 7.5% of the diet could be accomplished utilizing
GDDY (Gause and Trushenski, 2011b).
Although GDDY has shown promise as a protein source in feeds for
sunshine bass, no work has been performed with rainbow trout and
several aspects need to be addressed in order to confidently utilize the
product in formulations. Therefore, the objectives of this study were
to determine the digestibility of nutrients in GDDY for rainbow trout
and to evaluate GDDY's ability to support production performance of
rainbow trout as GDDY replaces fish meal protein in the feeds.