Fig. 4

mRNA expression analysis of the nine candidate genes (identified by GWAS) in male broiler testis tissue. a C _t values for the nine candidate genes and four housekeeping genes. b –log P value of the association between the expression levels of the nine genes and TeW and TeP of birds from the G₁₆ population, using two different housekeeping genes as an internal reference. c –log P value of the difference in expression levels across the nine candidate genes between the lean and fat lines of G₁₆, using two different housekeeping genes as an internal reference. d Difference in TCF21 expression level (\( 2^{{ -\Delta C{\text{t}} }} \) + SE) between the lean and fat lines at G₁₉, using two different housekeeping genes as an internal reference. *P < 0.05, TeW testis weight, TeP testis percentage