Estrogen and Progestogen Correlates of the Structure of Female Copulation Calls in Semi-Free-Ranging Barbary Macaques (Macaca sylvanus)

Females of many Old World primates produce conspicuous vocalizations in combination with copulations. Indirect evidence exists that in Barbary macaques (Macaca sylvanus), the structure of these copulation calls is related to changes in reproductive hormone levels. However, the structure of these calls does not vary significantly around the timing of ovulation when estrogen and progestogen levels show marked changes. We here aimed to clarify this paradox by investigating how the steroid hormones estrogen and progesterone are related to changes in the acoustic structure of copulation calls. We collected data on semi-free-ranging Barbary macaques in Gibraltar and at La Forêt des Singes in Rocamadour, France. We determined estrogen and progestogen concentrations from fecal samples and combined them with a fine-grained structural analysis of female copulation calls (N = 775 calls of 11 females). Our analysis indicates a time lag of 3 d between changes in fecal hormone levels, adjusted for the excretion lag time, and in the acoustic structure of copulation calls. Specifically, we found that estrogen increased the duration and frequency of the calls, whereas progestogen had an antagonistic effect. Importantly, however, variation in acoustic variables did not track short-term changes such as the peak in estrogen occurring around the timing of ovulation. Taken together, our results help to explain why female Barbary macaque copulation calls are related to changes in hormone levels but fail to indicate the fertile phase

Progesterone and pregnancy status of buffaloes treated with a GnRH agonist.

The primary aim of the present study was to establish whether the treatment with a GnRH agonist on Day 5 after AI may result in the formation of an accessory corpus luteum, greater progesterone secretion, and the increased likelihood of pregnancy success in buffaloes. The study was conducted during a period of increasing daylight length when progesterone secretion is suppressed and embryonic mortality is relatively high in buffaloes. In Experiment 1, treatment with a GnRH agonist (buserelin, 12 μg) on Day 5 after AI induced acute increases in circulating concentrations of LH, FSH and oestradiol-17β. Pregnant buffaloes (n=14) at Day 40 following AI showed an increase (Pb0.01) in milk whey progesterone concentration between Day 5 (310±55 pg/ml) and Day 15 (424±50 pg/ml). The non-pregnant buffaloes (n=7) showed a decrease (Pb0.01) in progesterone level from Day 5 (410±87 pg/ml) to Day 15 (188±30 pg/ml) following AI. In Experiment 2, the treatment with buserelin (12 μg) on Day 5 after AI induced ovulation in 62% of the buffaloes (31/50) and these buffaloes showed a progressive increase in milk whey progesterone concentration on Day 10, 15 and 20 of pregnancy. Buffaloes that did not ovulate, recorded a relatively constant milk whey progesterone level from Day 10 to Day 20 following AI. Milk whey progesterone concentrations increased after the administration of the GnRH agonist in 97% of the pregnant buffaloes and 68% of the non-pregnant buffaloes. The diameter of the largest follicle in buffaloes that ovulated (ovulated n=31) (8.9±0.04 mm; range 4.2 – 13.0 mm) did not differ significantly from the diameter of the largest follicle in buffaloes that did not ovulate (not ovulate n=19) (8.7±0.04 mm; range: 4.0 – 12.0 mm). The latter observation suggested that notional ovulatory size follicles in buffaloes are heterogeneous with respect to stage of follicle maturation and capacity to respond to plasma LH. The present study showed that treatment with a GnRH agonist on Day 5 following AI provides a strategy to increase progesterone secretion and the likelihood of pregnancy in buffaloes mated during periods of increasing daylight length

Embryo recovery in buffalo with timed ovulation and insemination subsequent to follicle superstimulation.

The aim of this study was to ascertain ovulation rate and non-surgical embryo recovery in buffalo treated with GnRH agonist-LH protocol, and injected with LH 12 or 24 hours after discontinuation of treatment with FSH. Mixed parity buffaloes (n=18) were randomly assigned to three groups: Groups 1 and 2 were implanted with GnRH agonist on Day -14 and injected with estradiol benzoate (10 mg) + progesterone (100 mg) on Day -6. Group 3 received an intravaginal progesterone device (PRID) with estradiol capsule on Day -6. Follicular growth was stimulated with FSH given as equal doses 2x daily in decreasing amounts from Day 0 to Day 4. On day 3 buffaloes were injected with PGF and PRID was removed from Group 3. Groups 1 and 2 were injected with 25 mg LH 12 h (Day 4, P.M.) and 24 h (Day 5, A.M.), respectively, after FSH. Buffaloes were mated by AI and embryo were recovered on Day 5 after AI. The number of follicles were similar among the groups. Group 1 had fewer ovulations and, consequently, corpora lutea compared to the other groups. Also embryo recovery was higher for Groups 2 and 3 compared to Group 1

Understanding the function of the corpus luteum and the onset of puberty in buffalo

This review aims to clarify some aspects of early buffalo reproduction and ovarian activity with special regard to corpus luteum activity. Puberty has been regarded as a complex event that is signalled by the first cyclic progesterone secretion > 1 ng/ml, in tight relation to other hormones such as LH and GH. Corpus luteum activity has been described in relation to the peculiarities of the oestrus cycle of the species, such as seasonal reproductive aptitude and the bull effect. The importance of CL in pregnancy establishment and maintenance has also been revised in the light of the results of the latest research about embryo mortality in buffalo

Influence of season on corpus luteum structure and function and outcome to artificial insemination (AI) in the Italian Mediterranean buffalo (Bubalus bubalis)

The aim was to ascertain whether relationships between corpus luteum (CL) vascularization, CL function, and pregnancy outcome in AI in buffaloes were consistent across the breeding season and transition period to the nonbreeding season in a Mediterranean environment. Stage of the estrous cycle in Italian Mediterranean buffaloes was synchronized using the Ovsynch with timed AI program and buffaloes were mated by AI in both the breeding season (N 131) and transition period (N 125). Detailed investigation of CL structure and function was undertaken in 39 buffaloes at each of the respective times using realtime B-mode/color-Doppler ultrasonography on Days 10 and 20 after AI. Progesterone (P4) concentrations were determined by RIA in all buffaloes. Pregnancy rate on Day 45 after AI was greater (P <0.05) during the breeding season (58.0%) than the transitional period (45.6%) and this was primarily the result of a lower (P <0.05) late embryonic mortality during the breeding season (7.3%) compared with the transition period (23%). Circulating concentrations of P4 on Days 10 and 20 after AI were greater (P<0.01) during the breeding season (4.6 and 3.4, respectively) than during the transition period (1.6 and 1.8 ,respectively), and this was independent of reproductive status as there was no interaction between pregnancy and season. Corpus luteum time average medium velocity at Day 10 after AI was greater (P< 0.01) during the breeding season (19.3) than in the transitional period (8.3). There were positive correlations in pregnant buffaloes between CL time average medium velocity and P4 concentrations on Day 10 (r= 0.722; P< 0.01) and Day 20 (r =0.446; P<0.01) after AI. The findings were interpreted to indicate that relationships between CL vascularization, CL function, and pregnancy outcome in AI in buffaloes are consistent across the breeding season and transition period to the nonbreeding season. The distinction between the breeding season and the transition period is the relatively low proportion of buffaloes that have CL function and P4 concentrations required to establish a pregnancy during the transition period, which is manifested in a greater incidence of embryonic mortality

Corpus luteum function and pregnancy outcome in buffaloes during the transition period from breeding to non-breeding season

The aim in this study was to investigate corpus luteum function and embryonic loss in buffaloes mated by artificial inseminations (AI) during the transitional period from breeding to non-breeding season. The study was carried out using 288 multiparous Italian Mediterranean Buffalo cows at 110 ± 4 days in milk. The buffaloes were mated by AI after synchronization of ovulation by the Ovsynch-TAI protocol 25 days after AI buffaloes underwent trans-rectal ultrasonography to assess embryonic development. Pregnancy diagnosis was confirmed on Days 45 and 70 after AI by rectal palpation. Buffaloes pregnant on Day 25 but not on Day 45 were considered to have undergone late embryonic mortality (LEM), whilst buffaloes pregnant on Day 45 but not on Day 70 were considered to have undergone foetal mortality (FM). Corpus luteum size and blood flow were determined by real-time B-mode/colour-Doppler on day 10 after AI in 122 buffaloes. The resistive index (RI) and pulsatility index (PI) were recorded at the time. Milk samples were collected on Days 10, 20 and 25 after AI in all inseminated buffaloes for the assay of whey P4 concentrations. Data were analysed by anova. Pregnancy rate on Day 25 after AI was 48.6% (140/288) and declined to 35.4% (102/288) and 30.6% (88/288) by Day 45 and Day 70 respectively. The incidences of LEM and FM were respectively 27.1% (38/140) and 13.7% (14/102). Pregnant buffaloes had greater (p < 0.01) whey concentrations of P4 from Day 20 onwards than buffaloes which showed LEM, whilst P4 in buffaloes that showed FM did not differ from the other two groups on Day 10 and Day 20. Corpus luteum blood flow on Day 10 after AI showed higher RI (p < 0.05) and PI (p = 0.07) values in buffaloes that subsequently were not pregnant on Day 25 compared with pregnant buffaloes. Buffaloes that were not pregnant on Day 45 also had a higher (p = 0.02) RI value on Day 10 than pregnant buffaloes, whilst PI values on Day 10 did not differ for the two groups of buffaloes. It was concluded that blood flow to the corpus luteum on Day 10 after AI influences corpus luteum function as judged by P4 secretion and also embryonic development and attachment in buffaloes

Gonadotrophin and prolactin secretion in castrated male sheep following subcutaneous or intracranial treatment with testicular hormones

Interactions between testosterone, estradiol, and inhibin in the control of gonadotrophin secretion in males are poorly understood. Castrated rams were treated with steroid-free bovine follicular fluid (bFF), testosterone, or estradiol and for 7 d (2 x 2 x 2 factorial design). Given independently, none of the exogenous hormones affected follicle-stimulating hormone (FSH) concentrations, but the combination of one or both steroids with bFF reduced FSH secretion. Testosterone and estradiol reduced luteinizing hormone (LH) pulse frequency (there was no synergism), and bFF had no effect. Plasma prolactin concentrations were not affected by any treatment. To locate the central sites of steroid action, castrated rams were bilaterally implanted in the preoptic area (POA), ventromedial nucleus (VMH), or arcuate nucleus (ARC). These implants did not affect FSH or prolactin concentrations, or LH pulse amplitude. The frequency of the LH pulses was not affected by testosterone in any site. Estradiol located in the ARC, but not the POA or VMH, decreased LH pulse frequency. In summary, FSH secretion is controlled by synergistic interactions between inhibin and estradiol or testosterone, whereas GnRH/LH pulse frequency is controlled by testicular steroids. Estradiol acts partly, at least, in the ARC, but the central site of action, testosterone remains unknown