Abstract: This study aimed to investigate the effects of key first parity production parameters and second parity mating season on the reproductive performance of French sows in their second parity under a multi-story pig building system, providing a scientific basis for optimizing 28-day batch production and gilt management strategies in such systems. Using reproductive records from 9 223 second parity French sows across four production lines in a large-scale multi-story pig farm in Guangdong, general linear model were employed to analyze the fixed effects of production line, breed, mating season, and first parity production parameters on second parity reproductive traits. Variance analysis revealed that production line, breed, second parity mating season, and first parity weaning-to-mating interval group had highly significant effects on second parity reproductive traits (P < 0.01), while first parity gestation length group and first parity litter size group had significant effects (P < 0.05). In 28-day batch production within multi-story pig buildings, optimizing gilt first mating age, precisely managing first parity gestation length, lactation period, litter size, and weaning-to-mating interval can effectively enhance the second parity reproductive performance of French sows.

Key words: French sows, reproductive performance, second parity sow, first parity production parameters, multi-story pig Farms, 28-day batch production