Ultrasonographic and endocrine aspects of follicle deviation, and acquisition of ovulatory capacity in buffalo (Bubalus bubalis) heifers

Ovarian Follicular Dynamics and Its Functional Significance in Relation with Follicle Deviation, Vaginal Cytology, and Hormone Profiles in Llamas (Lama glama)

The reproductive physiology in camelid species has its particularities. The present study aimed to characterize the ovarian follicular dynamics and its functional significance in relation to follicular deviation, vaginal cytological characteristics, and sexual hormone profiles in llamas as the first report in South American camelids. Non-pregnant, multiparous llamas (Lama glama; n = 10; age: 48−72 mo.; BCS: 2.5−3.0) were enrolled in the study. The ultrasonographic assessment was carried out transvaginally and follicular ablation was performed (day 0) when follicles were larger than 7 mm. The follicle number and diameter were scored daily throughout the process for a proper evaluation of the deviated follicles and to monitor the presence of new follicle pools (1.5 to 2.5 mm diameter). Vaginal cytological evaluation (parabasal, intermediate, and superficial cells) was performed every other day until day 6. Endocrine profiles (17β estradiol, anti-Mullerian hormone, testosterone, and progesterone) during pre- and post-follicular deviation were determined by using the ELISA assay. Differential follicular dynamics both in the presence of a single dominant follicle (DF) and in codominance during the follicular deviation process were detected in llamas (p < 0.05). The percentage of superficial cells was the most related to the follicular wave phase. However, the percentage of parabasal, intermediate, and superficial cells was not related to the phases of follicular growth, dominance, and regression (p > 0.05). Differential patterns among the different hormone concentration levels regarding the 17β estradiol, anti-Mullerian hormone, progesterone, and testosterone during follicular deviation were observed, with the latter being significantly different along the deviation process (p < 0.05). In conclusion, the use of vaginal cytology assessment would not be sufficient to determine the follicular phases in llamas. Therefore, complementary analyses, such as ultrasonography and endocrine assessment, are strongly recommended to determine follicular dynamics during the follicular deviation.

Use of Estradiol Cypionate to induce ovulation in buffalo raised in floodplain areas of Itacoatiara, Amazonas

ABSTRACT This study aimed to determine the efficiency of estradiol cypionate (EC) as an ovulation inducer in a Timed Artificial Insemination protocol. 69 buffalo cows received an intravaginal progesterone device and 2mg of estradiol benzoate (EB) at D0. On D9, the intravaginal device was removed and 0.53mg of prostaglandin (PGF2α) and 400UI of equine chorionic gonadotrophin (eCG) were applied. The cows were distributed into two groups: the first group received 1mg of EC (ECG) in D9, and the second group received 1mg of EB (EBG) in D10. Inseminations occurred on D11. Ovarian activity and pregnancy diagnosis were analyzed by ultrasonography. There was no difference (P>0.05) in follicular diameter (9.6 ± 0.89mm vs. 10.7 ± 1.12mm; P=0.06), in ovulation rate (90.9% vs. 90.9%; P=1) and pregnancy rate (58.8% vs. 62.9%; P=0.79), however, buffalo cows from the ECG treatment have less time between P4 removal and ovulation when compared to EBG buffalos (37.4h vs. 52.8h; P=0.001), respectively. Thus, it was concluded that the implantation of TAI in the floodplain of Amazonas is feasible and the use of EC results in successful rates, similar to EB.

Embryo transfer in buffalo (Bubalus bubalis)

The use of assisted reproductive technologies, such as superovulation and in vivo embryo production and in vitro embryo production (IVEP), has increased rapidly in recent years and is now applied worldwide for genetic improvement in beef and dairy buffaloes. Although in vivo embryo production has been shown to be feasible in buffalo, low efficiency and limited commercial application has been documented. These results could be associated with low antral follicle populations, high levels of follicular atresia and/or failures of the oocyte to enter the oviduct after superovulation. Additionally, IVEP technology has been shown to be an important tool for multiplying genetic material from donors of superior merit, and promising results have been achieved with the use of ovum pick-up (OPU) along with IVEP in buffalo. However, several factors appear to be critical for successful OPU/IVEP, including circulating levels of anti-Müllerian hormone, antral follicle populations, sizes of the follicles available for the OPU, reproductive seasonality, semen (sire) used for IVEP, donor category and farm. Furthermore, technologies applied to control follicular wave emergence and ovulation at predetermined times, without the need for estrus detection in recipients, has facilitated management and improved the efficiency of embryo transfer programs in buffalo herds. Conclusively, with the considerable evidence of poor results with in vivo embryo production in buffaloes, the association of OPU with IVEP represents a new alternative for the exploitation of buffalo genetics.

Effect of season on dairy buffalo reproductive performance when using P4/E2/eCG-based fixed-time artificial insemination management

This study aimed to compare the reproductive efficiency of dairy buffaloes subjected to TAI protocols based on progesterone, estrogen, and equine chorionic gonadotrophin (P4/E2+eCG) during the fall/winter (n = 168) and spring/summer (n = 183). Buffaloes received an intravaginal P4 device (1.0 g) plus estradiol benzoate (EB; 2.0 mg im) at a random stage of the estrous cycle (D-12). Nine days later (D-3), the P4 device was removed and buffaloes were given PGF_2α (0.53 mg im sodium cloprostenol) plus eCG (400 IU im). GnRH (10 μg im buserelin acetate) was administered 48 h after P4 device removal (D-1). All animals were subjected to TAI 16 h after GnRH administration (D0). Frozen-thawed semen from one bull was used for all TAI, which were all performed by the same technician. Ultrasound examinations were performed on D-12 and D-3 to ascertain cyclicity (presence of CL), D-3 and D0 to measure the diameter of the dominant follicle (ØDF), D+10 to verify the ovulation rate and diameter of the corpus luteum (ØCL), and D+30 and D+45 to detect pregnancy rate (P/AI 30d and 45d, respectively) and embryonic mortality (EM). Fetal mortality (FM) was established between 45 days and birth, and pregnancy loss between 30 days and birth. There were significant differences between fall/winter and spring/summer only for cyclicity rate [76.2% (128/168) vs. 42.6% (78/183); P = 0.02]. The others variables did not differ between the seasons: ØDF on D-3 (9.6 ± 0.2 mm vs. 9.8 ± 0.2 mm; P = 0.35); ØDF on D0 (13.1 ± 0.2 mm vs. 13.2 ± 0.2 mm; P = 0.47); ovulation rate [86.9% (146/168) vs. 82.9% (152/182); P = 0.19]; ØCL on D+10 (19.0 ± 0.3 mm vs. 18.4 ± 0.3 mm, P = 0.20); P/AI on D+30 [66.7% (112/168) vs. 62.7% (111/177); P = 0.31]; P/AI on D+45 [64.8%% (107/165) vs. 60.2% (106/176); P = 0.37]; EM [1.8% (2/111) vs. 3.6% (4/110); P = 0.95]; FM [21.9% (18/82) vs. 8.0% (7/87); P = 0.13]; and PL [23.8% (20/84) vs. 12.1% (11/91); P = 0.13]. In conclusion, dairy buffaloes present similar reproductive efficiency in fall/winter and spring/summer when subjected to P4/E2/eCG-based protocol for TAI.

Hormonal profile and follicular dynamics concurrent with CIDR and insulin modified Ovsync TAI programs and their impacts on the fertility response in buffaloes

Fifty one cyclic Egyptian buffaloes were used to study the hormonal profile and follicular dynamics concurrent with CIDR and insulin modified Ovsync TAI programs and their impacts on the consequent fertility responses. The buffaloes were randomly assigned into 3 ovulation synchronization protocols: Ovsync-alone (n = 13, control) CIDR-sync (n = 20) and Insulin-sync (n = 18). Ovsync-alone protocol consisted of two im injections of 20 μg bueserlin (GnRHa) on Day 0 (GnRH 1) and on Day 9 (GnRH 2) with an im injection of 500 μg of cloprostenol sodium (PGF₂ α) on Day 7. The CIDR-sync protocol consisted of the same treatment protocol as in Ovsync in addition to intra-vaginal insertion of CIDR (contains 1.38 gm of progesterone) on Day 0 followed by removal on Day 7. The Insulin-sync protocol consisted of the same treatment protocol as in Ovsync plus 3 sc injections of insulin at a dose of 0.25 i.u/1 kg, on Days 7, 8, and 9. Buffaloes in all groups were inseminated 16 h after GnRH2 by the same inseminator using frozen semen in straws. Blood samples were collected on Days 0, 3, 5 for serum progesterone assay and on Day 9 to measure serum concentrations of estradiol, insulin and IGF-1. Transrectal ultrasonographic scanning of the ovaries was conducted on Days 7, 8 and 9 to record the diameter of the largest follicle. Pregnancy diagnosis was conducted on Day 30 post-TAI by trans-rectal ultrasonographic scanning of the uterus to calculate conception rate. The serum progesterone concentration showed an increase (p < 0.01) in pregnant compared with non-pregnant buffaloes in both Ovsync-alone and Insulin-sync groups, but not in CIDR-sync group (p > 0.05) on Days 3 and 5. The serum estradiol concentration on Day 9 showed an increase (p < 0.01) in pregnant compared with the non-pregnant buffaloes in all of the treated groups. In Insulin-sync and Ovsync-alone groups, the diameter of the largest follicle (LF) was larger (p < 0.01) in pregnant compared with non-pregnant buffaloes, but in CIDR-sync, the diameter of the (LF) was larger (p < 0.01) in non-pregnant compared with pregnant buffaloes. Also, the results showed that the greatest diameter of LF was observed in pregnant buffaloes in Insulin-sync compared with either pregnant or non-pregnant buffaloes in all groups. It is concluded that modified CIDR-sync and Insulin-sync could improve fertility response through modulating hormonal profile and follicular dynamics in buffaloes during low breeding season.

Dominant follicles development and estradiol-17β concentrations in non-ovulating and ovulating post-partum Bulgarian Murrah buffaloes

This study was designed to evaluate the dominant follicles development and the estradiol-17β concentrations in non-ovulating and ovulating post-partum buffaloes. Sixteen Bulgarian Murrah buffaloes were submitted to transrectal ultrasonographic examination from the 1st post-partum day until day 50, 3 days apart. The follicular diameter of the different categories of follicles and the ovulations was recorded. The animals were allocated into two groups: I (n = 6) non-ovulating and II (n = 10) ovulating buffaloes. Serum estradiol-17β concentrations on the days for dominant follicle registration were measured by enzyme-linked immunosorbent assay. The results were statistically processed by analysis of variance, non-parametric and correlation analysis. The mean intervals between calving and first dominant follicle detection differed significantly (p < .05) among the groups (19.5 ± 6.2 vs. 13.8 ± 5.1 days), while the mean intervals between registered dominant follicles from two successive waves were comparable. The mean follicular diameters for the same category follicles in both groups were similar. Different estradiol-17β concentrations (p < .05) for the first dominant follicle between non-ovulating (23.5 ± 7.0 pg/ml) and ovulating (33.3 ± 8.4 pg/ml) buffaloes were determined. The cumulative percentages of buffaloes with firstly detected dominant follicle and ovulating animals correlated positively (r ≥ .84; p < .05) to post-partum days. In conclusion, non-ovulating and ovulating post-partum Bulgarian Murrah buffaloes showed differences in the development of the first dominant follicle and estradiol-17β concentrations during the time of dominant follicles detection.

The interval between the emergence of pharmacologically synchronized ovarian follicular waves and ovum pickup does not significantly affect in vitro embryo production in Bos indicus, Bos taurus, and Bubalus bubalis

The aim of the present study was to determine the optimal phase of the follicular wave to perform ovum pickup (OPU) for in vitro embryo production (IVEP) in various genetic groups. For this purpose, 27 heifers-nine Bos taurus (Holstein), nine Bos indicus (Nelore), and nine Bubalus bubalis (Mediterranean)-were maintained under the same nutritional, management, and environmental conditions. Heifers within each genetic group were submitted to six consecutive OPU trials with 14-day intersession intervals, at three different phases of the pharmacologically synchronized follicular wave (Day 1, 3, or 5 after follicular wave emergence), in a 3 × 3 crossover design. When OPU was performed at different phases of the pharmacologically synchronized follicular wave (Day 1, 3, or 5), no differences were found in the percent of oocytes recovered (70.5 ± 3.1%, 75.0 ± 3.1%, 76.0 ± 3.2%, respectively; P = 0.41) or blastocyst production rates (19.4 ± 2.9%, 16.6 ± 2.9%, 15.9 ± 2.6%, respectively; P = 0.36). Comparing genetic groups, B indicus showed a higher blastocyst rate (28.3(a) ± 2.8%; P < 0.01) than B taurus and B bubalis (14.1(b) ± 2.9% and 10.2(b) ± 2.0%, respectively). However, only B indicus heifers showed a variation in the number of visualized follicles and the total and viable oocytes along consecutive OPU sessions. In conclusion, different phases of the pharmacologically synchronized ovarian follicular wave did not affect OPU-IVEP in B indicus, B taurus, and B bubalis heifers. Additionally, B indicus heifers showed greater OPU-IVEP efficiency than did the other genetic groups, under the same management conditions.

Reference gene selection for gene expression analysis of oocytes collected from dairy cattle and buffaloes during winter and summer

Oocytes from dairy cattle and buffaloes have severely compromised developmental competence during summer. While analysis of gene expression is a powerful technique for understanding the factors affecting developmental hindrance in oocytes, analysis by real-time reverse transcription PCR (RT-PCR) relies on the correct normalization by reference genes showing stable expression. Furthermore, several studies have found that genes commonly used as reference standards do not behave as expected depending on cell type and experimental design. Hence, it is recommended to evaluate expression stability of candidate reference genes for a specific experimental condition before employing them as internal controls. In acknowledgment of the importance of seasonal effects on oocyte gene expression, the aim of this study was to evaluate the stability of expression levels of ten well-known reference genes (ACTB, GAPDH, GUSB, HIST1H2AG, HPRT1, PPIA, RPL15, SDHA, TBP and YWHAZ) using oocytes collected from different categories of dairy cattle and buffaloes during winter and summer. A normalization factor was provided for cattle (RPL15, PPIA and GUSB) and buffaloes (YWHAZ, GUSB and GAPDH) based on the expression of the three most stable reference genes in each species. Normalization of non-reference target genes by these reference genes was shown to be considerably different from normalization by less stable reference genes, further highlighting the need for careful selection of internal controls. Therefore, due to the high variability of reference genes among experimental groups, we conclude that data normalized by internal controls can be misleading and should be compared to not normalized data or to data normalized by an external control in order to better interpret the biological relevance of gene expression analysis.

Characterization of the exonic regions of the JY-1 gene in zebu cattle and buffaloes

Protein JY-1 is an oocyte-specific protein that plays an important regulatory role in the granulosa cell layer and during the early embryo development stages. It is the first specific protein of maternal origin discovered in a single-ovulating species. In this study, the exon regions of the JY-1 gene were characterized by sequencing in 20 unrelated cattle (Bos taurus indicus) and 20 unrelated buffaloes (Bubalus bubalis). Eighteen polymorphisms were detected in cattle and 10 polymorphisms in buffaloes. Some of the polymorphisms were identified in codifying regions and caused amino acid changes. The insertion of a thymine was detected in the codifying region of exon 3 of the buffalo sequence when compared to the cattle one. This insertion causes a change in the codons frameshift from this point onwards, modifying the 19 terminal amino acids of the buffalo protein and creating a premature stop codon. This finding may explain reproductive differences between cattle and buffaloes in terms of follicle recruitment, embryo development and incidence of twin pregnancies.