Analysis of breeding management of gilts in French herds; consequences on their lifetime reproductive performance

The influence of age at first farrowing and of the interval between arrival and fertilisation on the lifetime reproductiveperformance of sows was analysed using results from 35,631 crossbred Large White x French Landrace sows. Animals were born in 1990 and reared in 976 French herds which take part in the database of Technical Management of Sow Herds (GTTT). Herds were allocated to one of three groups according to their estimated breeding policy: early, medium or late first mating. Globally, late first farrowing increased litter size at birth and at weaning, the effect being most pronounced at the first litter. Early breeding did not worsen lifetime reproductive performance. The increase in age at first farrowing and/or in the interval between arrival and fertilisation had a positive effect on the number of weaned piglets per productive sow per year but negatively affected the length of reproductive life and the number of weaned piglets produced during the reproductive life of a sow or per sow per year. Income per sow per year, and production costs per weaned piglet (labour costs excluded) diminished with an increase in age at first farrowing and an increase in the interval arrival-fertilisation. It is not possible from the analysis of the results from herd breeding policies to conclude as to which is the optimum strategy to be used for breeding management of gilts.