Effect of age at first farrowing and herd management on long-term productivity of sows

Incidence of age at first farrowing and herd management on reproductive lifetime of sows was analysed on 38,349 Large White X Landrace animals and their 171,178 litters. Gilts were born in 1990 and located in 976 French herds. Data included dates of birth and entry in the herd, breeding, farrowing and weaning events, reason for and parity at culling. The herds were classified according to age at first farrowing, as 'early' (337 days), 'usual' (356 days) or 'late' (371 days). The average number of piglets born alive and weaned per litter increased with age at first farrowing (P < 0.001), especially at parity one. The total number of piglets produced per sow and the parity number at culling decreased with the age at first farrowing (P < 0.001). The best reproductive results were obtained in the 'usual' management group, with first farrowing at 356 days of age on average. Within each herd management, the older gilts at first farrowing obtained the lowest performance, and the youngest had the best ones. These results suggest that the effect of age at first farrowing on subsequent performance of gilts is highly dependent on the general sow herd management. (C) 1998 Elsevier Science B.V.