Abstract
Triploid fish are usually sterile. Thus, the energy and nutrients intended for sexual maturation may be available to enhance flesh quality and physical growth. The present study aimed to investigate differences in the metabolic substrates, lipids and proteins, between storage tissues from diploid and triploid female rainbow trout. Monthly, metabolic substrates were quantified in liver, muscle, and ovaries, which were collected during the first reproductive cycle. In general, it was possible to identify a seasonal and similar deposition of metabolites in different tissues of 2n and 3n females, mainly at early stages of gonadal maturation. However, from the stages 5-6, the ovaries showed great differences between ploidies, with higher concentration of lipids and protein in 2n females. This result reflects the incorporation of vitellogenin in oocytes, which is a process that does not occur in 3n females. It was possible to observe seasonal hepato-somatic index changes in 2n females, with higher values observed in the post-ovulatory stage, and the triploid animals showed lower values compared to 2n, with no seasonal difference. Viscero-somatic index can reflect the mobilization of substrates, with higher values found for 2n females in stage 5-6, which is the period of active mobilization of tissue substrates.
Highlights
Triploidy induction in fish has been used to avoid problems associated with sexual maturation, such as decrease in growth rates and carcass yield, as well as deterioration of sensorial properties of the flesh (Manor, Cleveland, Weber, & Kenney, 2015)
Triploid fish are usually sterile, the energy and nutrients intended for sexual maturation may be available to enhance flesh quality and physical growth (Penman, 2004)
The objective of the present study was to investigate the dynamics of metabolic substrates usually involved in vitellogenesis, between storage tissues of diploid and triploid female trout during their first reproductive cycle
Summary
Triploidy induction in fish has been used to avoid problems associated with sexual maturation, such as decrease in growth rates and carcass yield, as well as deterioration of sensorial properties of the flesh (Manor, Cleveland, Weber, & Kenney, 2015). The reproductive cycle of teleost fish is controlled by the brain-pituitary-gonad axis hormone regulation It includes the rearrangement of metabolic reserves and shifts in the composition of the energetic substrates in muscle, adipose tissue, and liver. Some recent data showed that the lack of ovary development in triploid trout altered the hepatic synthesis of some fatty acids, mainly the monounsaturated and polyunsaturated, and the mobilization of these specific fatty acids to the ovaries (Ribeiro et al, 2012). These data suggest a different pattern of energetic substrate mobilization in female triploid trout throughout the year. The objective of the present study was to investigate the dynamics of metabolic substrates usually involved in vitellogenesis, between storage tissues of diploid and triploid female trout during their first reproductive cycle
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