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Le cahier des charges en agriculture biologique (AB) interdit les traitements à base d’hormones ou substances analogues en vue de maîtriser la reproduction. En AB, la reproduction des petits ruminants est possible à contre-saison grâce à l’effet mâle. Les traitements lumineux sans mélatonine pour désaisonner la reproduction peuvent aussi être appliqués en bâtiments ouverts et sont compatibles avec le pâturage mais peu utilisés sur le terrain. L’insémination animale (IA) est peu répandue pour les ovins et caprins en AB, elle peut être réalisée sur chaleurs naturelles (saison sexuelle) ou induites et synchronisées par effet mâle (contre-saison). Dans les deux cas, les IA s’étalent sur plusieurs jours et nécessitent une détection des chaleurs préalable. En élevages caprins, la conduite en lactation longue est également une alternative pour désaisonner la production laitière. Dans les élevages porcins en AB, l’effet mâle peut faciliter l’induction de la puberté des cochettes, la stimulation d’œstrus de lactation, et la diminution de l’intervalle sevrage-œstrus ; toutefois il est utilisé principalement pour améliorer l’expression des chaleurs. La stimulation par le transport et le changement social et/ou d’environnement est largement utilisée pour induire et synchroniser les œstrus des cochettes de renouvellement. Chez les bovins, l’interdiction des traitements hormonaux n’est pas pénalisante en AB, car la reproduction est possible toute l’année par monte naturelle (majoritaire en élevage allaitant) ou par IA (majoritaire en élevage laitier) sur chaleurs naturelles. Dans toutes les espèces, le « flushing » alimentaire avant la mise à la reproduction est pratiqué dans le but d’améliorer la fertilité. La mise en œuvre de ces pratiques en AB est le résultat d’un équilibre entre enjeux financier, réglementaire et éthique.

Bisphenol A (BPA), an endocrine disruptor, has been replaced by structural analogues including bisphenol S (BPS). BPA and BPS exhibited similar effects regarding reproductive functions. Moreover, metabolic status and lipid metabolism are related to female fertility and could worsen BPS effects. The objective was to determine BPS in vivo effects on folliculogenesis and embryo production after chronic exposure through diet, and the influence of metabolic status in adult ewes. Sixty primiparous 2.5 year-old ewes, undergoing a restricted or well fed diet, were exposed to BPS (0, 4 or 50 µg/kg/day) for at least three months. After hormonal oestrus synchronisation and ovarian stimulation, ewes were subjected to ovum pick-up (OPU) procedures to collect immature oocytes, that underwent in vitro maturation, fertilisation and embryo production. Body weight, body condition score and plasma glucose were higher in well-fed compared to restricted ewes, while plasma NEFA was lower during the 4–5 months after the beginning of the diets. Plasma progesterone levels increased on day 5 before OPU session in well-fed compared to restricted ewes. No effect of BPS dose was observed on follicle population, plasma AMH levels and embryo production numbers and rates. However, a significant diet x BPS dose interaction was reported for cleaved embryos, > 4-cell embryos, blastocyst and early blastocyst numbers, and plasma triiodothyronine levels. Our study showed that a contrasted diet did not affect follicle population nor embryo production in adult ewes but could affect the quality and progesterone secretion of the corpus luteum. Chronic low BPS exposure had no effect on follicular population and oocyte competence. Nevertheless, the significant diet x dose interactions observed on embryo production suggest that BPS effect is modulated by metabolic status. Further studies are required to assess the risk of BPS exposure for public reproductive health.

In temperate regions goat's reproduction is seasonal. To obtain year-round breeding, hormonal treatments are currently applied. These treatments usually combine a progesterone analog with the pregnant mare serum gonadotropin (PMSG). However, their use has significant ethical and environmental drawbacks. Therefore, alternative methods to manage reproduction are needed. The discovery that in mammals the neuropeptide kisspeptin is a major positive regulator of hypothalamo-pituitary gonadal axis offered an attractive alternative strategy to control reproduction. We have previously designed a kisspeptin analog, called C6, which offers pharmacological advantages over endogenous kisspeptin. These include a longer lasting effect and enhanced activity following intramuscular injection. In the present work, we evaluated C6 effect on LH and FSH plasma concentrations in the Alpine goat breed and tested whether C6 could replace PMSG to trigger ovulation. An intramuscular injection of C6 (15 nmol/doe) given 24 hours after the end of progestogen treatment induced a surge-like peak of both LH and FSH. This was followed by an increase of progesterone, a hallmark of ovulation induction and corpus luteus formation. These results were obtained at three different time of the year: during the breeding season, the non-breeding season and at the onset of the breeding season. Furthermore, we compared the efficacy of C6 and PMSG to induce fertile ovulations when these treatments are given at the onset of the breeding season and are followed by artificial insemination. The results of this first attempt were extremely promising with gestation rates of 45% and 64% for C6 and PMSG respectively. Pending optimization of the treatment procedure in order to improve efficacy, kisspeptin analogs could be the long sought-after alternative to PMSG.