EXPERIMENTAL-STUDY OF THE EFFECTS OF AGE AT FIRST FARROWING AND DAM GENETIC TYPE ON LIFETIME SOW PRODUCTIVITY

This experiment was designed to estimate the effects of age at first f arrowing and dam genetic type on body development, longevity and produ ctivity of sows on the basis of five successive farrowings. Sixty-one Fl French Landrace x Meishan crossbred gilts (LF x MS) had a first mat ing either at 5 (M5) or at 7 months of age (M7) and were compared to 2 9 F1 French Landrace x Large White crossbred gilts (LF x LW) mated at 7 months of age (T7) and considered as controls. The highest longevity as well as the best overall reproductive performances were observed i n LF x MS sows mated at 5 months. The delay in body development observ ed over the first reproductive cycle became nonsignificant after the s econd or the third reproductive cycle. The numerical productivity esti mated from the age of 150 days to weaning of the fifth lifter was 29.4 , 27.0 and 23.3 pigs weaned/sow/year for M5, M7 and T7 sows, respectiv ely. As a consequence, the cost of the weaned pig was reduced by 27 F in M5 and by 19 F in M7 as compared to T7 pigs. However, under intensi ve management systems, this benefit is not large enough to reduce the loss due to lower growth and carcass performance in 1/4 Chinese termin al slaughter pigs.