During the postnatal life of pig, muscle growth is dependent on SC proliferation, differentiation and fusion to increase the DNA content of existing muscle fibers and their capacity for protein synthesis. In pigs, muscle fiber size and capillary density seem to be important factors that influence the meat quality and metabolic response at time of slaughter. Our findings suggested that differences between Langtang and Landrace pigs in fiber number and CSA may relate to the meat quality. The SCs in these two pig breeds may be the difference in proliferative potential. To test the difference in SC proliferation in the two breeds, an in vitro porcine primary muscle SC culture system was used. In this study, the SCs were Kaempferol isolated from the LD muscle from Lantang and Landrace pigs. In this system, proliferative ability was measured as the number of viable cells over a short period of 6 days. Although not significant for all time points, a tendency towards an overall difference in SC proliferation in Lantang and Landrace pigs was found. Specifically, the number of viable cells was significantly higher in Lantang pigs than in Landrace pigs at 72 h, implying that the SC proliferation rate was slower in Landrace pigs. Similar results were observed for muscle SCs isolated from low-weight, medium-weight and high-weight pig littermates; they each showed the different rate of proliferation. SCs from LW pigs have a significantly lower proliferation rate at day 3 compared with SCs from both MW and HW pigs. In addition, the same results have been found in poultry. A previous study demonstrated that SCs taken out of breast muscle and leg muscle tissues from White Plymouth Rock and WENs Yellow-Feathered chicks showed the different rate of proliferation at 72 h. In vivo, at any given time fewer SCs are available for fusion with existing muscle fibers because of the slower proliferation rate. When SCs are isolated from their natural environment and cultured in vitro under the same culture conditions, differences in the SC proliferation rate, as found in this study, must be due to the SCs themselves. Differences in the proliferation potential of SCs in vivo can be explained by differences in the Nitisinone nutrient supply, quantity of growth factors and fiber type. Thus, when SCs from the two breeds are cultured in vitro, differences in proliferation potential must be due to genetic factors.