The recent development of genomic selection induces dramatic changes in the way genetic selection schemes are to be conducted. This review describes the new context and corresponding needs for genomic based selection schemes and how reproductive technologies can be used to meet those needs. Information brought by reproductive physiology will provide new markers and new improved phenotypes that will increase the efficiency of selection schemes for reproductive traits. In this context, the value of the reproductive techniques including assisted embryo based reproductive technologies (Multiple Ovaluation Embryo Transfer and Ovum pick up associated to in vitro Fertilization) is also revisited. The interest of embryo typing is discussed. The recent results obtained with this emerging technology which are compatible with the use of the last generation of chips for genotype analysis may lead to very promising applications for the breeding industry. The combined use of several embryo based reproductive technologies will probably be more important in the near future to satisfy the needs of genomic selection for increasing the number of candidates and to preserve at the same time genetic variability.

During pregnancy. Reducing dietary energy supply resulted in a large decrease of lamb birthweight (-0.8 kg) and a diminution of the levels of glucose ( fig. 1), some non-essential (alanine, citrulline) and some essential (tyrosine, phenylalanine, threonine, valine, leucine) free amino acids ( fig. 3) in the blood of ewes ; blood urea increased ( fig. 2). Reducing body reserves caused a small drop in lamb birthweight (―0.3 kg) and an increment of glucose ( fig. 1) and free methionine ( fig. 3) in the blood. During the last 2 weeks of pregnancy, postprandial blood glucose level rose ( fig. 1).During lactation. During the first 2 weeks of lactation, the amino acid requirements for milk protein synthesis were higher than amino acid supply by the digestive tract ( fig. 5). At 1 week postpartum, ewes showed very high blood levels of most ot the essential free amino acids, free proline and free glycine (fig. 4). Some of the essential free amino acids (valine. leucine, phenylalanine, lysine, histidine) then decreased. Reducing body reserves resulted in an increment of most of the essential free amino acids in the blood. Blood levels of some of these amino acids seemed to be related to blood free methionine (table 5). Reducing the energy supply of the diet during late pregnancy increased blood glucose ( fig. 1 ).Introduction.

fig. 1 A). It contrasted with a large diminution in the spring (Grizard et al., 1979a, b). There was a decrease of glucose and of some non-essential free amino acids (alanine, glutamate, proline, citrulline) in the blood of the ewes. Most of the non-essential free amino acids decreased during the first day of life in the blood of lambs ( fig. 2A). Reducing body reserves resulted in an increase of glucose and glutamine but in a decrease of some other free amino acids (glutamate, ornithine, histidine) in the blood of ewes ( fig. 1 B). It increased daily weight gain during the first 3 weeks of life in lambs ( fig. 2B) (Grizard et al., 1977(Grizard et al., , 1979a. Celles-ci n'entraînent de réductions du poids

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for the lean and fat group -P < 0,100 ; 3,01 VS 3,84 kg for the low and high level -P < 0,001). Also, the growth rate of these lambs, after weaning at 6 weeks, was significantly reduced when their mothers were restricted to the maintenance level in late pregnancy (260 VS 288 g/day for the low and high level -P < 0,025).3. These effects were not observed in ewes of the autumn lambing, but lamb birth weights were usually a little lower than in spring.These results are discussed, with particular attention to seasonal effects which require more research, as these two experiments were not designed to test such effects.Introduction.