Reproductive performance in two organic sheep farming systems differing by the number of mating sessions in and out of the breeding season.

Hormonal treatments to control ovulation and the intensification of reproduction rhythm are usual strategies to increase ewe productivity. However, in organic farming the use of hormones is banned, making any increase of reproduction rhythm an inappropriate practice. This work tested if increasing the number of mating sessions per year could improve ewe annual productivity, while maintaining a non-intensive reproduction rhythm of one lambing per ewe per year.

Chronic low BPS exposure through diet impairs in vitro embryo production parameters according to metabolic status in the ewe.

Bisphenol A (BPA), an endocrine disruptor, has been replaced by structural analogues including bisphenol S (BPS).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.

Discontinuity in the molecular neuroendocrine response to increasing daylengths in Ile-de-France ewes: Is transient Dio2 induction a key feature of circannual timing?

In mammals, melatonin is responsible for the synchronisation of seasonal cycles to the solar year. Melatonin is secreted by the pineal gland with a profile reflecting the duration of the night and acts via the pituitary pars tuberalis (PT), which in turn modulates hypothalamic thyroid hormone status via seasonal changes in the production of locally-acting thyrotrophin. Recently, we demonstrated that, in the Soay sheep, photoperiodic induction of Tshb expression and consequent downstream hypothalamic changes occur over a narrow range of photoperiods between 12 and 14 hours in duration.

The kisspeptin analog C6 is a possible alternative to PMSG (pregnant mare serum gonadotropin) for triggering synchronized and fertile ovulations in the Alpine goat.

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).

Evaluation of hormone-free protocols based on the "male effect" for artificial insemination in lactating goats during seasonal anestrus.

Goat estrous and ovulatory responses to the "male effect" were characterized to determine the time range over which fertile ovulations occur after buck exposure. The results were used to explore the efficacy of different hormone-free artificial insemination (AI) protocols aimed at diminishing the number of inseminations needed to optimize fertility. Adult bucks and does were exposed to artificially long days during winter and then exposed to a natural photoperiod before buck exposure (Day 0).

Progesterone improves the maturation of male-induced preovulatory follicles in anoestrous ewes.

The first ovulation induced by male effect in sheep during seasonal anoestrus usually results in the development of a short cycle that can be avoided by progesterone priming before ram introduction. In elucidating the involvement of the hypothalamic-pituitary-gonadal axis in the occurrence of short cycles, the effects of progesterone and the time of anoestrus on the development of male-induced preovulatory follicles were investigated in anoestrous ewes using morphological, endocrine and molecular approaches. Ewes were primed with progesterone for 2 (CIDR2) or 12 days (CIDR12) and untreated ewes used as controls during early (April) and late (June) anoestrus.

The luteal outcome of anoestrus ewes induced to ovulate by the male effect is not related to the population of ovarian antral follicles before male exposure.

The ovarian status and its relationship with the response to the male effect were studied in Ile-de-France ewes entering anoestrus early (becoming anovulatory on January-February, n=13) or late (becoming anovulatory on March, n=13). The male effect was performed, in each group of ewes, at the beginning of the anoestrus season (March-April), approximately 35 days after ewes became anovulatory. Transrectal ultrasonography of ovaries was done at D-7, D-5, D-3 and D0 (ram introduction day) to examine the number and size of follicles ≥2mm, from D0 to D4 to analyze the ram-induced preovulatory follicles and at D14-D16 to identify luteal structures.

Reproductive cycle of goats.

Goats are spontaneously ovulating, polyoestrous animals. Oestrous cycles in goats are reviewed in this paper with a view to clarifying interactions between cyclical changes in tissues, hormones and behaviour. Reproduction in goats is described as seasonal; the onset and length of the breeding season is dependent on various factors such as latitude, climate, breed, physiological stage, presence of the male, breeding system and specifically photoperiod.

High fertility using artificial insemination during deep anoestrus after induction and synchronisation of ovulatory activity by the "male effect" in lactating goats subjected to treatment with artificial long days and progestagens.

The response to the male effect was studied in two Saânen and two Alpine flocks over 5 consecutive years. Adult male and female goats were exposed to artificial long days (16h light and 8h darkness, 16L:8D) in open barns for approximately 3 months (between December 1 and April 15) followed by a natural photoperiod. Goats were treated for 11 days with fluorogestone acetate (FGA) or progesterone (CIDR) immediately before joining.

Highly synchronous and fertile reproductive activity induced by the male effect during deep anoestrus in lactating goats subjected to treatment with artificially long days followed by a natural photoperiod.

The response to the male effect was studied in two flocks of Saanen and three of Alpine goats during deep anoestrus in three consecutive years. Males and females were subjected to artificially long days for about 3 months (between December 4 and April 1) followed by a natural photoperiod. Bucks joined goats 42-63 days after the end of the long days treatment (between April 20 and June 3) and fertilisation was ensured by natural mating.

Cloning and seasonal secretion of the pancreatic lipase-related protein 2 present in goat seminal plasma.

The storage of frozen semen for artificial insemination is usually performed in the presence of egg yolk or skimmed milk as protective agents. In goats, the use of skimmed milk extenders requires, however, that most of the seminal plasma is removed before dilution of spermatozoa because it is deleterious for their survival. It has been previously demonstrated that a lipase (BUSgp60) secreted by the accessory bulbourethral gland was responsible for the cellular death of goat spermatozoa, through the lipolysis of residual milk lipids and the release of toxic free fatty acids.