Aquaculture America 2020

February 9 - 12, 2020

Honolulu, Hawaii

EVALUATION OF GENETIC VARIATION AND GENE EXPRESSION PATTERNS OF DIFFERENT STRAINS RELATED TO SMD UTILIZATION IN LARGEMOUTH BASS

Han-Ping Wang, Shao-Kui Yi , Hong Yao,  Peng Xie, Xiao-Xia Li,
 Paul O'Bryant, and Dean Rapp
 
Ohio Center for Aquaculture Research and Development
The Ohio State University South Centers
 1864 Shyville Rd, Piketon, OH, 45661
wang.900@osu.edu
 

In order t o evaluate utilization variation of, and growth response to,  soybean  meal  diets in largemouth bass for breeding programs, test diets with 0%, 35%, and 50% fish meal  having been replaced by soybean meal (SBM; S0, S35, and S50) were administered to  three northern strains  of largemouth bass (LMB; Jones, Marlow, and Remlinger ).

In the S35 and S50 groups, the Marlow and Remlinger strains had much better growth res ponse to soybean meal diet (SMD) than  the  Jones strain , indicating  that  these two strains can better utilize diets containing high level  of SMD. The results suggest that sufficient genetic variation exists for growth and feed efficiency in LMB fed diets containing both  SBM and fishmeal , and  genetic improvement may be possible for the trait of  feed efficiency.  In all the three strains, t he growth performance of individuals in  the S35 and S50 groups obviously declined when compared with  the S0 group, and the specific growth rate and weight gain correlated  negatively with dietary levels of SBM .

Genes that were differentially expressed  between dietary SBM levels  were identified . Transcripts of genes related to insulin- signaling pathway and fatty acid metabolism and biosynthesis were significantly downregulated in  the S35 and S50 groups compared with the S0 group. Interestingly, several transcripts of genes (egfr , pla2g4 , and ugt) involved in GnRH-signaling pathway and steroid hormone biosynthesis were also downregulated in  the  S35 and S50 groups, inferring  that feeding with SMD could impair the sexual development of juvenile LMB .  Likewise, t he genes related to insulin signaling and fatty acid metabolism and biosynthesis were downregulated in  the Jones strain compared to  the  Marlow and Remlinger strains  in all three treatments. These results also suggest that insulin-signaling pathway and fatty acid metabolism and biosynthesis play important roles in adaptation to diets with high levels of SBM in LMB.  Overall,  the  Marlow and Remlinger  strains exhibited better adaptation to SBM diets, and could be considered as potential breeding candidates.

This  study provides useful information for LMB breeding programs, and  it contributes to  our  understanding  of genetic mechanisms related to growth performance of LMB fed with high levels of SMB.