This study was conducted at Tamdiep pig nuclear Research and Development station belonging Thuyphuong Pig Research Center - National Institute of Animal Sciences from 2002 to 2013. The aim of study was to evaluate the factors such as generation, parity and year that influence the reproductive performance of VCN03 sows. Data structure included the reproductive performance of 362 VCN03 sow with 1129 litters over 4 generations. There was no relationship between generation factor and the reproductive performance of VCN03. Other factor such as parity affecting Number born alive and the weight of weaned pigs (P0.01). The year factor was not associated with number born alive and piglet weight per litter. However, this factor was demonstrated affecting the piglet weight at birth, the number and weight of weaned pig per litter (P0.001). The VCN03 sows were used in breeding program as a sire line, therefore, they had a lower reproductive performance compared with other breeds. Number born alive and weaned pigs were 8.85 and 8.15 piglets. These reproductive traits of VCN03 decreased over 4 generations (P0.05). Number born alive and weaned pigs were low at parity 1
witnessed an increase in second parity, fluctuation from 3th parity to 6th parity and decline at 7th parity. Number born alive varied each year (P0.05) and number of weaned pigs was fluctuated without the direction over the years.