Grass valorisation and muscular characteristics of blonde d'Aquitaine steers

The blonde d'Aquitaine breed, the males of which are traditionally raised a s young steers in intensive systems, is spreading beyond its region of orig in. In pasture regions these males could be introduced into more extensive grazing systems. The purpose of this study is to assess the capability of t hese animals to valorise forage resources and also the characteristics of t he carcasses produced and of the muscles concerned when considering meat te nderness. The study used young weaned bulls reared as beef animals and slau ghtered at 33 months of age (n = 22 and 24). These beef animals use 2 very different types of pasture during the pasturing seasons (April-November). D uring the first winter period of rearing the Blonde d'Aquitaine show a lowe r ingestion of forage (5.8 kg dry matter.100 kg(-1) life weight vs. 7.5 kg dry matter.100 kg(-1) life weight) and lower growth than the Charolais (115 0g.d(-1) vs. 1400g.d(-1)). At pasture, the activity of the animals is simil ar (380 minutes at pasture, 52 bites per minute for speed of ingestion). At slaughter, at the same body weight (695 kg), the Blonde d'Aquitaine have a greater weight of muscle (+ 9%, 335 kg of muscle vs. 308 kg). The Blonde d 'Aquitaine have a more glycolytic muscular metabolism (1497 mu mol. min(-1) .g(-1) vs. 1351 mu mol.min(-1).g(-1)), a higher proportion of fast, IIB fib ers (63.6% vs. 58.8%) and less collagen (3.7 mug d'OH-prol.mg(-1) of DM vs. 5.2 mug d'OH-prol.mg(-1) of DM). These results show that animals of blonde d'Aquitaine breed provide a good valorisation of forage and grass and that under these breeding conditions, they produce muscles with favourable char acteristics for production of tender meat.