The Effect of Fish Meal Replacement with Low-gossypol Cottonseed Meal on the Flesh Quality of Golden Pompano(Trachinotus ovatus)

In order to investigate the effect of replacing fish meal with low-phenol cottonseed meal (LCSM) on flesh quality, antioxidant capacity and related gene expression of golden pompano, 4 groups of LCSM-added feeds were prepared to replace 0% (LCSM0), 20% (LCSM20), 40% (LCSM40) and 60% (LCSM60) fish meal protein and golden pompano of 28.42±0.02 g were fed for 6 weeks. The results are as follows. First, there was no statistically significant difference in flesh hardness, elasticity, cohesion, glue viscosity and recovery between LCSM20 group and LCSM0 group (P>0.05), and the adhesion and chewiness of LCSM20 group decreased significantly (P < 0.05); the cohesion of LCSM40 group and LCSM60 group increased significantly (P < 0.05), and the other texture indexes decreased significantly (P < 0.05). Second, there was statistically significant difference in pH and cooking loss rate of LCSM20, LCSM40 and LCSM60 group compared with LCSM0 group (P < 0.05), and there was no statistically significant difference in flesh drip loss rate (P>0.05). Third, there was no statistically significant difference in mass fraction of collagen of LCSM20 and LCSM40 group compared with LCSM0 group(P>0.05). Fourth, the content of malondialdehyde (MDA) and the activity of glutathione peroxidase (GSH-Px) in LCSM20 group showed no change compared with LCSM0 group (P>0.05), but the SOD activity was down-regulated in LCSM20 group (P < 0.05). There was no statistically significant difference in MDA content between LCSM40 and LCSM60 group compared with LCSM0 group (P>0.05). The SOD activity and GSH-Px content were deceased in LCSM40 and LCSM60 group (P < 0.05). Fifth, there was no statistically significant difference in the transcription level of flesh quality-related genes (Decorin, MSTN, MyoG and CatL) in LCSM20 group compared with LCSM0 group (P>0.05). The COL1α1 and CatB gene transcription levels were significantly up-regulated (P < 0.05). The transcription levels of MSTN and COL1α1 genes in the LCSM40 and LCSM60 groups were significantly up-regulated compared with LCSM0 group (P < 0.05). In addition, the transcription levels of Decorin, MyoG, CatB and CatL genes in the LCSM40 group were no statistically significantly different from those in LCSM0 group (P>0.05); the Decorin gene transcription level in the LCSM60 group was significantly down-regulated compared with LCSM0 group (P < 0.05), the MyoG gene transcription level was no statistically significantly different from that in LCSM0 group, and CatB and CatL gene transcription levels were significantly up-regulated compared with LCSM0 group (P < 0.05). In summary, with the effect on flesh quality, antioxidant capacity and related gene expression as evaluation indicators, the optimal amount of LCSM addition in the golden pompano feed is 20%.