Effect of sexual maturation on growth, fillet composition, and texture of female rainbow trout (Oncorhynchus mykiss) on a high nutritional plane

Nutrient and energy demands of sexual maturation influence fillet composition and texture in many fish cultivars. Effects of sexual maturation on growth and on fillet composition and texture were investigated in rainbow trout on a high nutritional plane. Diploid (2N; fertile) and triploid (3N; sterile) female rainbow trout were reared from July 2008 through spawning in March 2009. Growth rates were greater in the 2N females from August through October; whereas, the reverse response was true in February and March, resulting in similar overall growth rates and body weight (3140 ± 76 g). Raw fillets were softer, regardless of ploidy, between September and January (Allo-Kramer shear) compared to July, but increased again in March (366.79 g/g). By November, 2N females had lower fillet fat content and higher moisture content than 3N females. Fat content negatively correlated with shear force (r = − 0.35, R2 = 0.12). Alkaline-insoluble (a-i) hydroxyproline (HYP) concentration was similar for 2N and 3N muscle through January but increased 2 and 4 folds for 3N and 2N muscles, respectively, by March. A-i HYP positively correlated with energy of shear (r = 0.41, R2 = 0.17). In summary, during the five months prior to spawning and in females on a high nutritional plane, increased accumulation of fat in 3N females resulted in decreased firmness of raw fillets; whereas, increased insoluble collagen content, primarily in 2N females, increased fillet firmness in the month of spawning.