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In a preceding study, complete substitution of fish meal protein with cottonseed meal (CM) protein did not affect the survival or growth rate of adult rainbow trout over a 6-mo period. Gossypol, a naturally occurring compound in cottonseeds, has an antifertility effect in terrestrial animals, but information regarding salmonid fish is lacking. Female rainbow trout in this experiment were fed diets with either 0, 25, 50, 75, or 100% (diets 1 to 5) of the fish meal protein replaced with CM protein until first maturation and spawning to study long-term effects on growth and reproduction. Feeding diets containing CM over a total period of 10 mo did not result in differences in growth and mortality compared to the control group (P [is greater than] 0.05). Increased CM incorporation levels resulted in decreased (P [is less than] 0.05) blood hemoglobin (10.6 [+ or -] 1.3, 8.4 [+ or -] 1.8, 7.3 [+ or -] 1.1, 6.9 [+ or -] 0.8, and 5.6 [+ or -] 1.4 g/dL) and hematocrit (49.6 [+ or -] 3.9, 38.5 [+ or -] 9.3, 34.4 [+ or -] 3.7, 34.8 [+ or -] 4.9 and 28.0 [+ or -] 6.8 %) levels in diets 1 to 5, respectively. The CM incorporation level had no effect (P [is greater than] 0.05) on the number of eggs produced per female but led to a reduction (P [is less than] 0.05) in egg weight. Eyed stage survival of embryos was low in all dietary groups and did not show differences (P [is greater than] 0.05). However, an increasing CM incorporation level led to a linear increase (P [is less than] 0.05) in the number of females that produced no viable embryos (23.1, 37.5, 42.9, 60.0, and 71.4%). Gossypol in the diet was absorbed by the female trout and transferred to the eggs (0, 2.2 [+ or -] 0.5, 6.7 [+ or -] 1.6, 10.6 [+ or -] 4.2, and 20.0 [+ or -] 2.6 [micro]g/g in diets 1 to 5, respectively). A high concentration of gossypol remained in the juveniles at the swimup stage (endogenous yolk-absorbed) (0.6 [+ or -] 0.3, 2.4 [+ or -] 0.3, 3.4 [+ or -] 0.0, and 4.7 [+ or -] 1.0 [micro]g/g, diets 2 to 5, respectively). The findings suggest that replacement of the dietary fish meal protein with CM protein has no effect on fish growth and mortality but may lead to a reduction in reproductive performance in female rainbow trout. Key Words: Cottonseed oil meal, Egg Quality, Gossypol, Salmonidae, Steroid Hormones

La situation des populations de corégones a été définie par rapport à l'eutrophisation des lacs qui ne cesse d'augmenter. Le soutien de stocks de ces poissons implique le développement de piscicultures de repeuplement et en conséquence de la maîtrise de l'élevage des stades larvaires et juvéniles. Les aspects physiologiques, comportementaux et nutritionnels des stades précoces des corégones ont été examinés. Cette étude insiste particulièrement sur l'absence de la fonction stomacale chez les corégones au stade précoce. Les aspects comportementaux comprennent : la quantité maximale de nourriture, la fréquence des repas, la dépendance à l'intensité lumineuse et la densité d'élevage. Les aliments secs composés testés sur les corégones différaient de manière significative des aliments distribués jusqu'alors avec succès aux larves de poissons sans estomac. Une liste des conditions optimales d'élevage de larves et de juvéniles de corégones est énumérée en conclusion.