Foreword: The increase in sow prolificacy : present knowledge, possible developments and consequences. Communications presented during a meeting of the INRA Commission on Pig Research

Abstract

Prolificacy in sows is currently increasing very rapidly. The use of synthetic lines of pigs, derived from crossbred between Chinese and European breeds, will result in a further elevation of the number of piglets produced per sow and per year. However, the increase in litter size may have a number of consequences on the survival and performance of the piglets and on the longevity of sows. The INRA Commission on Pig Research organised a meeting on the topic. The communications that were given during the meeting are summarised in a number of short papers that are presented here.

The improvement in sow performance during the last ten years in the French pig herds was first assessed (J. Dagorn et al). The main possible ways of increasing sow prolificacy were then presented, considering both those that are currently applied and the ones that can be envisaged for the future. The possible improvements that have resulted or could result from selection (C. Legault, J.-P. Bidanel), from a better knowledge of the physiology of ovulation (M.-A. Driancourt et al) and embryonic development (M.Terqui and F. Botté) were presented, as well as the developments that can be envisaged from the identification of genes involved in follicular growth (F. Hatey).

In a second part, the consequences of increased prolificacy on the sows themselves or on the piglets were examined. Some consequences have already been observed as a result of the currently achieved elevation of prolificacy. Possible further consequences that may be expected if the present tendency to increased litter size is maintained, have also been envisaged. The problems encountered in rabbit production have been presented as an example of what could happen in swine production (G. Bolet).

The possible consequences of increased prolificacy were then considered under different perspectives including genetics (J.-P. Bidanel), nutrition of the sow and of the foetuses (A. Prunier and H. Quesnel, J.-Y. Dourmad et al, N. Quiniou et al, M. Etienne and M.-C. Père), survival and growth of the piglets (P. Herpin and J. Le Dividich).