Discussion
The growth performance of pigs and their meat quality depend on the interactive effects of genotype, rearing conditions, pre-slaughter handling, and carcass/meat processing [15]–[17]. The present study focused on evaluating the effects of breed and dietary protein/energy ratio on growth performance, carcass composition, and meat quality. We found significant interaction effects of breed and diet on growth performance and carcass composition. Bama mini-pigs grew more slowly than Landrace pigs, and their carcasses were composed of less lean meat and more fat than those of Landrace pigs. These findings indicate that there are obvious differences in carcass composition between breeds, as previously reported [18], [19]. Furthermore, the backfat in the native breed was much thicker than that in the Landrace breed. This was expected, as Landrace pigs are the result of several years of genetic selection through Mendelian genetics and molecular genetics approaches for traits including increased growth rate and reduced fat content [20]. Within each breed, pigs fed the NRC diet had considerably higher dressing percentage than those fed the GB diet. However, in Landrace pigs, GB diet promoted carcass length and lean percentage, especially during the growing phase. The accelerated development of bones and muscle may have resulted from compensatory growth due to low nutrition. Landrace pigs fed the NRC diet deposited less fat than Bama mini-pigs. This may result from the high capacity for muscle growth of fast-growing genotypes, such as Landrace pig, which can utilize high nutrient diets without increased lipid deposition.