Changes in muscle gene expression related to metabolism according to growth potential in young bulls.

To analyse the effects of genetic selection in favour of high muscle development on muscle gene expression, oligonucleotide microarrays were used to compare the transcriptome of Longissimusthoracis muscle from 15- and 19-month-old Charolais bull calves divergently selected for high (H) or low (L) muscle growth. Transcriptome data revealed that about two thirds of the genes involved in glycolysis were up-regulated at 15 and at 19months of age in H animals. Lastly, some differentially expressed genes were associated with muscle mass in the carcass (FGF6, PLD2) independently of fat deposition and meat quality. Selection for muscle growth potential is associated with modified expression of some genes involved in growth, and also with increased expression of genes involved in glycolysis. Furthermore, this change in muscle metabolism is likely to be dissociated from fat deposition and beef quality, providing new criteria for genetic selection in favour of muscle growth.