Flesh qualities and muscle fiber characteristics in triploid and diploid rainbow trout

Abstract

Analyzed with regard to their slaughter weights and flesh quality 78-month-old diploid and triploid rainbow trout (full sibs) were reared together in a pond after tagging at an age of 12 months. Triploids had higher body weights and carcass percentages than diploids (6 kg vs 4 kg and 66% vs 52%). Triploid fish also displayed lower electrical conductivity values and darker (L* value) and redder (a* value) flesh color. The fillets of the triploid trout contained more crude fat and less moisture than the diploids (6% vs 3% and 68% vs 74%, respectively). No effect of ploidy was found with regard to the protein contents. Triploid rainbow trout had larger mean white and intermediate muscle fiber areas than diploid fish in the dorsal and pelvic fin regions. In the pelvic fin part, the white muscle fiber areas were larger than in the dorsal fin part. In conclusion, adult triploid rainbow trout grow faster especially by fiber hypertrophy and have better flesh quality parameters than diploid fish.

Selection for muscle fat content and triploidy affect flesh quality in pan-size rainbow trout, Oncorhynchus mykiss

“…In the present study, we observed that triploid fish had larger white muscle fibers than diploid fish (+9% and + 15% of the mean diameter for the L line and F line, respectively). Such an effect of triploidy on muscle fibers size was already reported in salmonids (Bjørnevik et al, 2004;Johnston et al, 1999;Poontawee et al, 2007;Sigurgisladottir et al, 2001;Suresh and Sheehan, 1998). In the present study, higher values of lightness were found for both raw and cooked fillets of triploid fish.…”

“…This suggested a cumulative effect of the higher lipid content and triploidy status on muscle fiber size to induce a softer flesh. In previous studies, the lower firmness of the triploid fish fillet was often related to the higher muscle or body fat content of triploid fish (Bjørnevik et al, 2004;Poontawee et al, 2007). We could presume that in the present study, there was no difference in muscle fat content between 2n and 3n fish because we found no difference in the muscle dry matter content, and these two parameters are strongly and positively correlated (Crossin and Hinch, 2005).…”

“…Brighter fillets for triploid fish were also obtained with pan-size rainbow trout (Werner et al, 2008). However, such an effect of triploidy on fillet lightness was not observed with larger (900 g) rainbow trout (Choubert et al, 1997), and darker fillets in triploid fish were even observed in large (N 2 kg) rainbow trout (Poontawee et al, 2007) and Atlantic salmon (Bjørnevik et al, 2004). Thus, the muscle fiber size may have an impact on the fillet lightness, but this parameter does not seem to be the main determinant.…”

“…These effects of triploidy on fish biology may lead to consequences in flesh quality, as reported in various salmonid species. Differences between diploid and triploid fish were demonstrated in muscle fiber size, fillet gaping, color, texture and some muscle biochemical characteristics, such as protein solubility (Bjørnevik et al, 2004;Gomez-Guillén et al, 2000;Poontawee et al, 2007;Werner et al, 2008).…”

Comparison of growth performance, biochemical and fatty acid compositions between all-female diploid and triploid rainbow trout Oncorhynchus mykiss (Walbaum, 1792)

“…For Nile tilapia (Oreochromis niloticus), Pechsiri and Yakupitiyage (2005) stated that moisture, lipid and ash content showed no significant difference between ploidy groups; however, in contrast to previous studies, protein content of the triploid group was greater than diploids. Poontawee, Werner, Müller-Belecke, Höstgen-Schwark, and Wicke (2007) reported that there was a significant difference between 6.5 year-old diploid and triploid rainbow trout in terms of fat and moisture, but that the ploidy leveldid not affect the protein contents. Segato et al (2006) reported that triploid shi drums (Umbrina cirrosa) deposited more fat in their livers than did the diploids.…”