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Abstract Largemouth bass (Micropterus salmoides, LMB) is an important aquaculture species due to its excellent flesh quality and environmental adaptability. It has been continuously introduced to many countries and cultured for decades. Here, an LMB population was used for selective breeding to improve growth rate and feed adaptability. After five generations of breeding, the growth rate improved by 38%, and feed adaptability improved by 22% compared to the non-breeding population. To study the underlying genetic mechanism, 100 LMB from the breeding population and 100 from the non-breeding population were sampled for whole-genome resequencing. The population genetics analysis shows that the breeding population has a higher inbreeding coefficient and linkage disequilibrium (LD) level, a lower nucleic acid diversity and effective population size (Ne). Using $$F_{ST}$$ (fixation index), we found that the average $$F_{ST}$$ value between the two populations was 0.07, with the highest $$F_{ST}$$ value reaching 0.38, which overlaps with the trypsin gene. Additionally, other genes exhibiting high $$F_{ST}$$ values are associated with functions such as neural development, glucose metabolism, and growth. Using $$F_{ST}$$ and nucleic acid diversity as criteria, we identified 698 genes that are positively selected in the breeding population, and gene functional enrichment analysis shows that 36 genes are related to the olfactory receptor pathway. Overall, our study found that multiple genes were selected in the LMB breeding population. These genes may be associated with adaptation and digestion of artificial feed in fish.

Fishmeal quality is of great importance for production of aquatic animals particularly shrimp; however it varies widely depending on raw materials and processing methods. A seven week feeding trial was conducted using five diets to examine effects of fishmeal quality on growth performance, protein digestibility and expression of gene regulating trypsin in Litopenaeus vannamei. Each test diet was fed four times daily to four groups of shrimp with an average initial weight of 2.2 g shrimp-1. The shrimp fed S1-premium grade fish meal (S1-PGFM) diet attained the highest weight gain, specific growth rate with the best feed conversion ratio (FCR) and protein utilization efficiency. Growth of shrimp fed S2-PGFM, grade 1 FM and grade 2 FM containing diets was inferior to those of S1-PGFM fed group. The imported FM diet fed group showed the slowest growth and feed utilization efficiency. FCR of shrimp fed grade 2 FM and imported FM was significantly the poorest (p

Fishmeal quality is of great importance for production of aquatic animals particularly shrimp; however it varies widely depending on raw materials and processing methods. A seven week feeding trial was conducted using five diets to examine effects of fishmeal quality on growth performance, protein digestibility and expression of gene regulating trypsin in Litopenaeus vannamei. Each test diet was fed four times daily to four groups of shrimp with an average initial weight of 2.2 g shrimp-1. The shrimp fed S1-premium grade fish meal (S1-PGFM) diet attained the highest weight gain, specific growth rate with the best feed conversion ratio (FCR) and protein utilization efficiency. Growth of shrimp fed S2-PGFM, grade 1 FM and grade 2 FM containing diets was inferior to those of S1-PGFM fed group. The imported FM diet fed group showed the slowest growth and feed utilization efficiency. FCR of shrimp fed grade 2 FM and imported FM was significantly the poorest (p<0.05). In-vitro protein digestibility using crude enzyme extract from shrimp fed reciprocal diet was not significantly different among treatments but in-vivo protein digestibility of the S1-PGFM fed group was the highest (92.06+0.42%) in concordance with the highest trypsin gene expression. [ABSTRACT FROM AUTHOR]