The current challenge in aquaculture revolves around the quest for new, economically, and environmentally sustainable species. Species occupying lower trophic levels, such as Liza aurata, may represent promising candidates for aquaculture. Nevertheless, when formulating diets with high or total fishmeal substitution, it can potentially influence their growth and health status (Estruch et al. 2015). Thus, in this study the growth and health status through the transcriptome of posterior intestinal section was assessed in Liza aurata fed with two experimental diets containing 15% and 0% of fishmeal.
Material and Methods: Sixty Liza aurata (9.14 ± 1.52 g) were randomly distributed in 6 tanks of 600 L (0.9kg/m3) under recirculation system. Two different diets, with 15% (HP15) and 0% (HP0) fishmeal inclusion, were tested in triplicate. Monthly sampling was carried out to analyse fish growth and survival and specific growth rate (SGR), daily feeding rate (FIR) and feed conversion ratio (FCR) were calculated. Once was finished the trial, 5 fish from each treatment were slaughtered, beyond 5 initial fish, in order to assess the transcriptome of posterior intestinal section (FISABIO, Spain). We focused on transcripts with a padj value of less than 0.05. Enrichment analysis of GO and KEGG terms was conducted using the Fisher Exact Test.
Results and discussion: Fish weight Gain, SGR and FCR showed significant differences (Table 1), indicating improved growth in the diet with higher fishmeal content. Despite being an omnivorous species, juvenile stages exhibited more carnivorous feeding habits.
Confirming these results, the intestinal transcriptome provided a total of 321 differential expressed transcripts (DETs). From the comparison HP0 vs HP15, 207 and 114 were were down and up-regulated, respectively. After GO enrichment analysis, results showed that 4 biological processes (BP) were significantly affected by the rearing conditions, mainly related to cell proliferation. Besides, KEGG analyses revealed 7 disturbed pathways, related to cellular proliferation and metabolism, particularly, protein digestion and absorption (ko04974). Therefore, a differential intestine expression was reported based on rearing conditions. In conclusion, relative high fishmeal requirements seem to be necessary in Liza aurata at juvenile state.
Acknowledgments
This work was supported by Generalitat Valenciana (GVA AICO/2021/198). J. Brol has a predoctoral grant from Generalitat Valenciana (Programa Santiago Grisolía 2021; CIGRIS/2021/109). R. Olivares-Perona has a technician contract was funded by European Union Next Generation-Plan de Recuperación-Ministerio de Ciencia e Innovación-Gobierno de España (TED2021-129272B-C21).