Effect
of feeding cottonseed meal-containing diets to broodstock rainbow trout and
their impact on the growth of their progenies
J. Rinchard, K.J. Lee, S. Czesny, A. Ciereszko, K.
Dabrowski
Aquaculture, 227(1-4): 77-87
Abstract:
Rainbow trout Oncorhynchus mykiss broodstocks
were fed five experimental diets in which fish meal protein was gradually
replaced with cottonseed meal (CS) protein (0%, 25%, 50%, 75%, and 100%;
diets 1–5, respectively) during a 22-month period. The effect of
increasing dietary levels of CS on reproductive performance was gender
specific. Sperm fertilizing ability significantly decreased when CS exceeded
50% protein replacement (72.6±2.0%, 73.6±2.0%, 69.0±3.3%, 43.3±5.1%, and
36.8±4.7%, for diets 1–5, respectively). In contrast, in females, the
viability of embryos was only significantly affected at 25% and 50%
replacement levels (56.7±15.6%, 20.5±24.9%, 11.4±18.6%, 48.8±25.9%, and
39.6±31.1%, for diets 1–5, respectively). Progenies from multiple parents
per dietary treatment were combined and reared on a commercial diet over a
2- or 3-month period fed at a rate of 4% of their body weight. The paternal
origin (fresh sperm, experiment 1) had a highly significant effect on growth
performance of progenies, and progenies from males fed with 25%, 50%, and
75% CS grew significantly (P<0.05) faster than progenies from
males fed with 0% and 100% CS. Growth performance of progenies produced
using cryopreserved sperm (experiment 2) was not affected regardless of the
CS levels fed to male rainbow trout. Progenies from females (experiment 3)
fed a diet containing 50% CS grew significantly (P<0.05) slower
than the other groups. Sex ratio was examined histologically after
completion of feeding experiments with progenies. Regardless of maternal or
paternal origin, males dominated among the progenies. Thus, we postulated
that other substances such as flavonoids, present in the CS and possibly
transferred to yolk sac reserves, might affect the sex ratio in favor of
males.
(School of Natural Resources, The Ohio State
University, Columbus, OH 43210, USA, e-mail: dabrowski.1@osu.edu)