Ovarian follicular dynamics and hormonal profiles in heifer and mixed-parity Mediterranean Italian buffaloes (Bubalus bubalis) following an estrus synchronization protocol.

The primary objective was to elucidate ovarian follicular dynamics and hormonal profiles in nulliparous heifer (HE; n = 11 ) and mixed-parity (MP; n=10 ) Mediterranean Italian water buffaloes (Bubalus bubalis) following an estrus synchronization protocol. Both groups received a progesterone releasing intravaginal device (PRID) implant for 10 days; a luteolytic dose of synthetic prostaglandin was given 7 days after PRID insertion. Daily ultrasound monitoring and collection of blood to determine plasma concentrations estradiol and progesterone started 1 day after PRID removal and lasted for 55 and 65 days in HE and MP buffaloes, respectively. Data analysis was restricted to the first 5 days after PRID removal and to one estrus cycle following induced ovulation. The HE buffaloes were not inseminated and only one ovulated within 5 days after PRID removal; the remainder ovulated between 8 and 48 days after PRID removal (except one in which ovulation was never detected). All HP buffaloes were inseminated 72, 96 and 120 h after PRID removal; seven buffaloes ovulated within 5 days after PRID removal and two were pregnant. Mean diameter of the largest follicle was significantly smaller in HE than MP buffaloes the first 4 days after PRID removal. There was a parity by time interaction ( P=0.0047 ) for plasma progesterone concentrations; progesterone was higher in HE than MP buffaloes 1 day after PRID removal, but the converse was true 2 days after PRID removal. After induced ovulation, HE buffaloes exhibited a one-wave ( n=5; length of cycle, 8-12 days), two-wave ( n=4; range: 20-26 days) or three-wave cycle ( n=1; 25 days). In contrast, all non-pregnant MP buffaloes ( n=8 ) had a two-wave cycle (range: 19-25 days). For buffaloes with two-wave cycles, the growth rate and diameter of the largest follicle was significantly smaller in HE than MP buffaloes for both the first follicular wave (1.3mm versus 1.7 mm per day and 10.5 mm versus 13.3 mm, respectively) and the second follicular wave (1.0 mm versus 1.3 mm per day and 11.0 mm versus 13.8 mm). In conclusion, there were many significant morphological and endocrine differences between HE and MP buffaloes.

Hormonal dynamics and follicular turnover in prepuberal Mediterranean Italian buffaloes (Bubalus bubalis).

The aim of this study was the investigation of hormonal and ovarian follicular dynamics in prepuberal buffaloes (Bubalus bubalis) bred in Italy. Eleven 5-9-month old buffalo calves ranging in weight from 122 to 270kg, maintained under controlled nutritional and environmental conditions, underwent 50 days of ultrasonographic ovarian follicular monitoring in the months of October-December. Blood sampling for E(2) and FSH determination and ultrasonographic monitoring using a 7.5MHz linear probe and an ALOKA SSD-500 monitor were performed daily. No differences in any of the parameters under study were highlighted when calves were divided into two weight categories (<200 and >200kg) and thus data were pooled. In this study, values are reported as mean+/-S.D. A range of two-six regular follicular waves was reported among calves with an average of 4+/-1.1. Overall interval (days) between wave emergence was 9.9+/-2.8 and largest diameters (mm) of dominant and first subordinate follicles were 8.4+/-1.2 and 4.8+/-0.6, respectively (P<0.05). With the exception of one calf, some minor follicular waves (short waves or SWs; 1.6+/-1), lasting <10 days (6.1+/-1.2) were reported. They were monitored contemporaneously on the ovary contralateral (n=7) or ipsilateral (n=3) to the main follicular wave. Growth rate (mm per day) of dominant follicles (DF) was significantly faster than for corresponding subordinate follicles (SF) and follicles of SWs (1.08+/-0.2 versus 0.79+/-0.1 and 0.83+/-0.1, respectively, P<0.05). The static phase (days) lasted longer in DF compared to SF and SW (5.4+/-1.8 versus 2.4+/-1.2 and 2.6+/-1, respectively, P<0.05). The regressing phase (mm per day) was similar among DF, SF and SW (0.86+/-0.2, 0.94+/-0.2 and 0.84+/-0.1, respectively, P=0.09). Episodic spikes of E(2) and FSH were reported, corresponding to wave development throughout the course of investigation. In conclusion, the majority of buffalo calves displayed a typical pattern of regular follicular development in conjunction with a dynamic trend of ovarian and hypophyseal hormones. Some minor follicle turnover was reported with parallel main follicular waves.

Hormonal stimulation and oocyte maturational competence in prepuberal Mediterranean Italian buffaloes (Bubalus bubalis).

The objective of this study was to determine the best combined hormonal treatment to utilize in order to obtain a high number of good quality in vivo and in vitro matured oocytes from prepuberal Mediterranean Italian buffalo calves (Bubalus bubalis). Transvaginal ultrasound follicular aspiration was employed to recover oocytes from antral follicles. Fifteen barn housed buffalo calves, between 5 and 9 months of age were used in this study and randomly divided into control (Group A) and treated groups. A commercially available preparation of 2000 IU eCG was administered to animals in the treatment groups, followed by 2000 IU of hCG given either 12 h (Group B), or 24 h (Group C) before ovum pick up (OPU). From the time of administration of eCG treatments, the best timing for hCG administration before OPU was determined and integrated with the administration of 500 IU of FSH-LH in a decreasing dosage protocol over 4 days (Group D). Expanded cumulus oocyte complexes (COCs) recovered from all groups were immediately fixed for later aceto-orcein staining. All other COCs were processed for in vitro maturation using standard procedures and then fixed and stained for assessment of nuclear maturation. Collectively, hormonal stimulation did not increase the number of ovarian antral follicles available compared to the control group (P > 0.05), but did result in higher output of medium (Group B: 9.8 +/- 7.1; Group C: 3.4 +/- 6.7; Group D: 15.6 +/- 4.9 versus Group A: 1.6 +/- 2.2) and large follicles (Group B: 44.8 +/- 22.9; Group C: 8.7 +/- 6.1; Group D: 70.2 +/- 10 versus Group A: 6.1 +/- 6.3). Administration of hCG 12 h before follicle aspiration proved to be the best strategy to obtain high numbers of immature and mature oocytes from antral follicles (P < 0.05; Group B: 70.8 +/- 12 and Group D: 82 +/- 12.6 versus Group A: 43.6 +/- 13.9 and Group C: 27.2 +/- 13.9). A significantly higher number of expanded COCs was obtained from hormonally stimulated groups compared to the control group (P < 0.05; Group B: 28.7 +/- 16.8, Group C: 16.3 +/- 5.9 and Group D: 27.1 +/- 16.9 versus Group A: 6.2 +/- 6). A higher oocyte maturational competence (P < 0.05) was found in Groups A, B and D (80.8 +/- 7.9, 87.5 +/- 8.2, and 86.5 +/- 4.3, respectively) compared to Group C (60 +/- 26.2). In conclusion, in prepuberal buffalo calves combined gonadotrophin stimulation protocols yielded higher numbers of medium to large size follicles compared to a control group. A high number of good quality oocytes were recovered by transvaginal ultrasound follicle aspiration, and a high rate of metaphase II progression was reached after in vivo and in vitro maturation.