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The aim of this review is to discuss selection of maternal lines, to present last results and to draw research prospects. Firstly, we discuss the genetic variability of the maternal quality traits. A divergent selection experiment on uterine capacity was performed in Spain during eight generations; results put forward the hypothesis that there was a major gene affecting uterine capacity. Reproductive performance could be improved by including female fertility in a selection program but response to selection would be probably very low. Even if genetic correlation between prolificacy traits and growth traits are, in general, positive, the litter size effect, introduced in the statistical models of growth traits, is always highly significant and negative, showing the well known phenotypic relationship between litter size and weights. One spreading method for analysing female longevity data is survival analysis which allows inclusion of both censored and uncensored records of animals. Development of computer programs has made it possible to estimate the genetic potential of does for a longer productive life and to the genetic parameters for longevity. Studies have been conducted to settle adequate models of analysis and this criterion could be included in the selection objective. Later we draw up an inventory of the 19 on going selection experiments in six different countries. Significant differences in direct genetic effects for litter size or litter weight were found. An alternative to the selection of maternal lines for crossbreeding could be the development of a multi-purpose line, through simultaneous selection for litter size and growth traits.

Finally we propose some …