Effect of feeding cottonseed meal-containing diets to broodstock rainbow trout and their impact on the growth of their progenies
2003
Rinchard, J. | Lee, K.J. | Czesny, S. | Ciereszko, A. | Dąbrowski, Kazimierz
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 (56.7ł15.6%, 20.5±24.9%, 11.4ł18.6%, 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.
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