A 180 day field trial was carried out to study the growth performance, gene expression, fillet quality and fatty acid profile of male and female GIFT tilapia. Four month old male (180 fish with an average body weight of 72.75 ± 0.76 g) and female (180 fish with an average body weight of 72.25 ± 0.76 g) tilapia were segregated manually by seeing their genital papilla and were stocked, separately, in six hapas (60 fish/hapa) with each sex in triplicate conditions. The stocked fish were fed twice a day, with GROWPIA feed (floating pellet – 3 mm dia; crude protein - 28 %), at the rate of 5–8 %. The study found significant difference in growth performance between male and female GIFT tilapia. After 180 days of culture, male GIFT tilapia showed significantly higher specific growth rate (4.31 ± 0.001 % /day), average body weight gain (737.85 ± 0.25 g) and feed utilization indicators in terms of better apparent feed conversion ratio (1.69 ± 0.05), higher feed efficiency ratio (0.59 ± 0.02) and protein efficiency ratio (2.10 ± 0.07) compared to female GIFT. On the other hand, the female GIFT tilapia displayed downregulation in the gene expression of IGF-1/IGF-2, myoD, myogenin and upregulation of myostatin. However, the study did not find any significant difference in survival rate at the end of experiment. Similarly, there was no significant difference in fillet yield (%) and it was in the range of 43.93–45.49 % between male and female GIFT tilapia. Fillet nutritional quality analysis indicated significantly lower moisture (76.43 %) and ash (4.27 %) contents and higher crude lipid content (12.41 %) in female GIFT tilapia. Interestingly, the study found statistically similar fatty acid profile between male and female tilapia, however, the fatty acid contents of PUFA (19.38 ± 0.69 %), DHA/EPA (2.56 ± 0.38), omega-3 fatty acid (5.11 ± 0.32 %) and omega-6 fatty acid (14.27 ± 0.37 %) was found to be slightly better in male GIFT tilapia. Overall, the study found better growth performance in male GIFT tilapia and nutritionally similar fillets quality between male and female GIFT tilapia.
Read full abstract