Qualité des fourrages : de la plante à la ration alimentaire (Session n°2)

The quality of forages : from the plant to the animal's diet (Session n°2)

This is a synthetical and critical presentation of the papers of the session n°2 of the European Grassland Congress (La Rochelle, 27-30 May 2002).
The quality of forages remains a subject attracting much attention : a quarter of the papers were devoted to it. The breeding of forages for an improvement quality through techniques of molecular biology is a recent research subject ; other, more traditional, approaches are being adapted to new production conditions (nutritive value of forages in less intensive production systems and/or in systems where legumes play a greater role).
Three different directions for future research work on the forages were identified : 1) improvement of the prediction of forage intake and protein digestion (to the traditional in vivo and in vitro methods must be added the large development of near infra-red spectrometry for the rapid determination of the chemical composition of the forages, their digestibility and voluntary intake... and also that of new methods for the prediction of intake aptitudes especially through model building), 2) a better knowledge of the composition of what is taken in by herbivorous stock (especially in extensified systems ; description of models simulating the dynamics of a herd/grazed plot system) and of the spatial distribution of the effects of browsing (defoliation and refusals) on the swards, 3) development of more basic research work on the factors that determine forage quality so as to be able to act on them, these factors being those that are responsible for the build-up of the sward structure, and also the molecular and biochemical bases of the plants' composition. Other directions of research ought also to be strengthened : on what determines voluntary intake and diet selection, on more diversified forage species, on the nutritive value of grass-legume associations, etc.