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

Author
item AUSSANASUWANNAKUL, AUNCHALEE - West Virginia University
item KENNEY, P. BRETT - West Virginia University
item Weber, Gregory - Greg
item YAO, JIANBO - West Virginia University
item SLIDER, SUSAN - West Virginia University
item MANOR, MEGHAN - West Virginia University
item SALEM, MOHAMED - West Virginia University

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2011
Publication Date: 4/15/2011
Citation: Aussanasuwannakul, A., Kenney, P., Weber, G.M., Yao, J., Slider, S.D., Manor, M.L., Salem, M. 2011. Effect of sexual maturation on growth, fillet composition, and texture of female rainbow trout (Oncorhynchus mykiss) on a high nutritional plane. Aquaculture. 317:79-88.

Interpretive Summary: In many fish such as trout, fillet quality and growth rate decreases as the fish develop eggs. This is due to nutrients and energy that would normally go to muscle growth, instead going to the gonads. Effects of sexual maturation on growth, fillet composition and texture were investigated in rainbow trout fed to near satiation so that nutrients and energy from the diet were not limited and the fish had extensive stores of fat before egg development. We compared diploid females which are normal fish with 2 sets of chromosomes that are fertile and grow eggs, and triploid females which have 3 sets of chromosomes and are sterile and do not grow eggs. Female rainbow trout were reared from July 2008 through spawning in March 2009. Growth rates were greater in the diploid females early on, August through October; whereas, the reverse response was true in February and March when eggs were largest, resulting in similar overall growth rates and body weight (3140+/-76 g). Seasonal changes in the texture of raw fillets were observed for both the fertile diploids and sterile triploid fish. During the five months prior to spawning in these well-fed fish, increased accumulation of fat in the sterile triploid females resulted in decreased firmness of raw fillets; whereas, increased insoluble collagen content, primarily in the diploid females, increased fillet firmness in the month of spawning. In all, female fish fed to near satiation maintained a positive growth rate and satisfactory fillet quality traits over the course of gonad development. Causes of changes in fillet quality traits over this period were identified.

Technical Abstract: Nutrient and energy demands of sexual maturation influence fillet composition and texture in many fish cultivars. Effects of sexual maturation on growth, and 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 fold for 3N and 2N muscle, 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.