Efficacy of the Ovsynch protocol for synchronization of ovulation and fixed-time artificial insemination in Murrah buffaloes (Bubalus bubalis)

Upgrading the fixed-time artificial insemination (FTAI) protocol in Romanian buffaloes

The present study describes the challenges of assisted reproduction in Romanian buffaloes while increasing the efficacy of artificial insemination by choosing the most suitable method. The modified fixed-time artificial insemination (FTAI) protocol with sexed semen was used to increase the conception rate. This study included a total of 80 buffalo heifers that received ovarian stimulation using the OvSynch protocol. Two groups (n = 40), namely, a control group, in which the classic FTAI method was performed, and an experimental group, in which deep intrauterine AI was performed in cows that had developed a dominant follicle (US+UcFTAI), were randomly selected. The conception rate (CR) was 63.6% in the experimental group, which was statistically higher (P < 0.05) than the control group (30%). The ultrasound examination indicated that, using the OvSynch protocol, 82.5% (33 out of 40) of buffaloes developed a dominant follicle (DF) while the distribution between the warm and cold seasons was 75 and 90%, respectively. The CR was 60% during the hot season and 66.6% during the cold season. At calving, 92.5% female fetuses were born. The improved FTAI method in this study enhanced the results by reducing the waste of sexed semen and maximizing the response to OvSynch, making it a recommendation for practitioners. This study presents preliminary results and highlights that genetic progress is difficult to achieve. A systematic approach is needed in order to choose the most suitable biotechnological method for each farm.

Study on Various Luteal Characteristics Using Doppler Ultrasonography for Early Pregnancy Diagnosis in Nili-Ravi Buffaloes

The objective of current study was to assess the trend in various luteal characteristics viz luteal size (LS), plasma progesterone (P⁴) concentration, and luteal blood flow (LBF) using color Doppler imaging (CDI) and power Doppler imaging (PDI) modes in pregnant and nonpregnant Nili-Ravi buffaloes. Lactating, cyclic, and healthy Nili-Ravi buffaloes (n = 09) without any reproductive abnormality were selected in present study. Buffaloes were synchronized using Ov-Synch, and fixed-time artificially insemination was performed (day = 0). Pregnancy was diagnosed on 30-day post-AI using B-mode ultrasonography based on presence or absence of embryonic heartbeat. Ovaries of all animals were scanned from day 5 till 21 post-AI using both B-mode and Doppler ultrasonography to measure LS and LBF. After each ovarian ultrasound examination, blood samples were collected via jugular venipuncture to determine plasma P⁴ concentration. According to results, LBF using CDI and PDI was significantly higher (P ≤ 0.05) in pregnant buffaloes on days 13 and 15 post-AI, respectively. The mean LS and plasma P⁴ concentration did not differ (P ≥ 0.05) between pregnant and nonpregnant animals until day 15 post-AI. However, a significant difference (P ≤ 0.05) was noticed for both on day 17 and onwards. It is concluded that LBF is a more sensitive luteal character as compared to LS and P⁴ for earlier pregnancy diagnosis in Nili-Ravi buffaloes when ascertained through CDI.

GPGMH, a New Fixed Timed-AI Synchronization Regimen for Swamp and River Crossbred Buffaloes (Bubalus bubalis)

The crossbreeding of Swamp and River type buffalo breeds is practiced for the improvement of milk yield and reproductive performance in swamp buffalo herds. This study aimed to modify the Ovsynch synchronization protocol (GPG) and improve the fixed-timed artificial insemination (FTAI) for better reproductive performance of crossbred buffaloes. Comparison of four conventional synchronization protocols [pregnant mare gonadotropin-prostaglandin F₂α-gonadotropin-releasing hormone (PmPG), gonadotropin-releasing hormone-prostaglandin F₂α-gonadotropin-releasing hormone (GPG), prostaglandin F₂α-gonadotropin-releasing hormone-prostaglandin F₂α-estradiol benzoate (PGPE), and progesterone-pregnant mare gonadotropin-prostaglandin F₂α-gonadotropin-releasing hormone (P₄PmPG)] in crossbred buffaloes showed that the GPG protocol treated buffaloes displayed higher (P < 0.05) estrus response with an increasing tendency in ovulation (84.6%) and pregnancy rates (30.8%) than PmPG, PGPE, and P₄PmPG treated buffaloes. Buffaloes treated with a dose of 0.4 (mg/kg) mifepristone combined with GPG, exhibited higher (P < 0.05) estrous response (82.4%), ovulation (94.1%), and pregnancy (47.1%) rates compared with other doses (0, 0.3, or 0.5 mg/kg) groups. Injection of mifepristone along second GnRH injection in buffaloes improved (P < 0.05) pregnancy rate (35.3%) when compared to before or after the second GnRH of GPG protocol. Single AI after 24 h of mifepristone or second GnRH injection seems the best time to enhance the pregnancy rates in buffaloes compared to double or other single AI times in the modified GPGMH protocol. In comparison, GPGMH reduced the follicular cyst incidence (P < 0.05) with increasing ovulation (P > 0.05) and pregnancy rates (P > 0.05) than the P₄GPG and GPG protocols in crossbred buffaloes. The current study supported that new synchronization protocol (modified of GPG protocol; GPGMH) by the inclusion of mifepristone (with a dose of 0.4 mg/kg along second GnRH), AI after 24 h of mifepristone or second GnRH, and human chorionic gonadotropin (hCG at day 5 of AI) enhance the ovulation and pregnancy rates in crossbred buffaloes.

Effects of age and season on conception rate of Mediterranean Italian Dairy Buffalo (Bubalus bubalis) following oestrus synchronization and fixed-time artificial insemination

The objective of this project was to report the effects of season and age on conception rate amongst Italian Mediterranean Buffalo subjected to an Ovsynch/Resynch (O/R) reproductive management protocol. The study utilized nulliparous (heifers), primiparous buffalo cows (PBC) and multiparous buffalo cows (MBC). The primiparous and multiparous groups were subjected to the synchronization protocol throughout the entire year, but heifers were synchronized and inseminated only during the spring/summer seasons. The conception rate obtained following the OvSynch oestrus synchronization protocol, applied during spring, was 68.4% for heifers, 83.3% for PBC and 67.7% for MBC. The overall total conception rates following the complete O/R protocol were 84.27%, 94.4% and 79%. Conception rates achieved during summer were heifers 52%, PBC 47.2% and MBC 49%, whilst overall conception rates following the full O/R protocol were 72%, 69.8% and 58.2% respectively. In the autumn seasons, PBC conceived 58.9% and MBC 52.1% following initial Ovsynch, which improved to total overall conception rates of 87.5% and 78.7% following the full O/R protocol. Similarly, in the winter season, PBC experienced a conception rate of 47.5% following Ovsynch and 72.5% after a follow-up Resynch. MBC experienced 60.0% and 74.4% conception following Ovsynch and full O/R, respectively, during winter. Total conception rates during all seasons were quite acceptable following the O/R protocol. There was a significant decrease from spring to summer in conception rate for all parity groups, but heifers were not a severely affected as older buffalo cows. This finding agrees with that of other investigators indicating that heifer fertility is not as negatively impacted by long photoperiod and higher ambient temperature as that of older animals. The O/R protocol as utilized in this study is an effective means of reproductive management for dairy buffalo cows and is effective for improving fertility during out-of-season breeding.

Spirulina platensis extract addition to semen extender enhances cryotolerance and fertilizing potentials of buffalo bull spermatozoa

The objective of this study was to investigate the effect of Spirulina platensis extract (SPE) addition to the freezing extender on freezability, lipid peroxidation, ultrastructure alterations and fertilizing potentials of frozen-thawed buffalo bull spermatozoa. Semen samples were collected with artificial vagina from five adult fertile bulls and diluted with Tris-base extender containing SPE (1, 5, 10 and 20 μg/mL) or without SPE (control). Diluted semen was cooled to 4 °C throughout one hour and frozen in 0.25 mL straws: prior to being stored in liquid nitrogen. Cryopresreved spermatozoa were assessed for post-thawing sperm motility, viability, acrosomal integrity, ultrastructure changes, antioxidant activities, lipid peroxidation and fertility rate. The current results clearly indicated that adding 10μg/mL SPE to the freezing extender significantly improved (P< 0.05) post-thawing motility and decrease the percentage of acrosomal damage (51.67±6.02% and 16.33±1.46%, respectively) compared with the control (28.33±4.41% and 26.33±1.77%, respectively). Moreover, addition of 10 μg/mL SPE to the semen extender significantly diminished (P< 0.05) MDA concentration (10.66±2.40 nmol/10⁹) compared with the control (22.66±4.26 nmol/10⁹). Therefore, the present results revealed that addition of 10μgl/mL SPE to the freezing extender might improve semen quality and reduce cryodamage of the buffalo bull spermatozoa.

Evaluation of Ovsynch versus modified Ovsynch program on pregnancy rate in water buffaloes: a meta-analysis

Ovsynch is a widely accepted estrus synchronization protocol for improving the reproductive performance of water buffaloes who manifest low reproductive efficiency. Recently, some modified protocols based on Ovsynch such as 2 injections of prostaglandin 14 days apart following the Ovsynch are also introduced to enhance the reproductive potential of this species. In the present study, a meta-analytical assessment was performed with the objective to evaluate the reproductive performance of water buffaloes synchronized with Ovsynch or modified Ovsynch programs. Meta-analysis of the fixed or random effects model was determined by the heterogeneity among the studies. Reproductive outcome of interest was pregnancy per artificial insemination (P/AI) measured on day 25 (25-100). A total of 32 articles including 4003 buffaloes using either Ovsynch or modified Ovsynch protocol were reviewed. In the random effects model for buffaloes, the overall proportion of P/AI was 42.55% [95% confidence interval (CI): 37.48-47.70; n = 3,089] and 46.44% (95% CI: 39.63-53.31; n = 914) on day 25 after AI for Ovsynch and modified Ovsynch, respectively. Results for P/AI were then categorized by ovarian activity, where P/AI was available for 3575 cyclic buffaloes and 320 non-cyclic buffaloes. For cyclic buffaloes, the overall proportion of P/AI was 47.54% (95% CI: 42.72-52.38; n = 2911) and 57.97% (95% CI: 54.12-61.77; n = 664) on day 25 after AI for Ovsynch and modified Ovsynch, respectively. In the fixed effects model for non-cyclic buffaloes, the overall proportion of P/AI was 19.68% (95% CI: 13.48-26.58; n = 167) and 33.01% (95% CI: 25.50-40.94; n = 153) on day 25 after AI for Ovsynch and modified Ovsynch, respectively. In conclusion, a benefit for P/AI is detected in buffaloes with the modified Ovsynch protocol. Besides, whichever estrus synchronization protocols (Ovsynch or modified Ovsynch), cyclic buffaloes have higher P/AI compared with non-cyclic buffaloes.

Reproductive management in buffalo by artificial insemination

Artificial insemination (AI) is important for genetic improvement and to control the period of breeding in buffalo and has increased significantly over the past 20 years. AI is more difficult in buffalo compared with cattle due to variable estrous cycles, reduced estrous behavior, and reproductive seasonality. The latter is associated with a higher incidence of anestrus and increased embryonic mortality during the nonbreeding season. Protocols to control the stage of the estrous cycle have undergone recent development in buffalo. These protocols are based on the control of both the luteal phase of the cycle, mainly by prostaglandins and progesterone, and follicle development and ovulation, by prostaglandins, progesterone, GnRH, hCG, eCG and estradiol. Protocols that synchronize the time of ovulation enable fixed timed AI, avoiding estrous detection. Factors to consider when selecting an AI protocol include animal category (heifers, primiparous or pluriparous), reproductive status (cyclic or anestrus), and season. This review looks at the current status of estrus synchronization and AI in buffalo and provides some practical suggestions for application of AI in the field.

Synchronization with controlled internal drug release (CIDR) and prostaglandin F2α (PGF2α) influences oxidant/antioxidant biomarkers and mineral profile in summer-stressed anoestrous buffalo (Bubalus bubalis)

During the summer season, high ambient temperature in tropical and subtropical countries exposes buffaloes to oxidative stress that have antigonadotropic and antisteroidogenic effects. Uses of hormonal therapy can improve the state of ovarian inactivity caused by heat stress and cause anoestrous buffaloes to come into oestrus and successfully achieve pregnancy. Therefore, this study was designed to detect the role of oxidative stress in production of the anoestrous state in summer heat stressed buffaloes and the effects of treatment by Controlled internal drug release (CIDR) in solving of this problem. Also it monitored the changes in Oxidant/antioxidant biomarkers and mineral profile before and after the treatment. Forty buffaloes with no signs of oestrus for more than 120 days after calving were selected. The animals were divided into two groups: the first group (group I, n = 25) was subjected to treatment with CIDR, while the second group (group II) received no treatment and was considered the control group (n = 25). Blood samples were collected before treatment, after treatment and after 45 days of oestrus. The serum level of TAC, MDA, NO, ascorbic acid (vitamin C), P, Cu and Zn were measured. The results showed that 80% of treated buffaloes came into oestrus. The conception rate was 75%. TAC concentrations were significantly higher in group I than in group II. There were significant decreases in the mean values of MDA, NO and ascorbic acid in the buffaloes in oestrus, but these values increased when the buffaloes became pregnant. In contrast there were no significant differences in the mean values of MDA, NO or ascorbic acid in the buffaloes that came into oestrus but failed to conceive. The mean serum P, Cu and Zn values were significantly increased (P < 0.05) in the buffaloes that came into oestrus compared to the control animals. The levels of P and Zn significantly increased when the buffaloes became pregnant and remained unchanged when they failed to conceive. In conclusion, known physiological and pathological variations in the oxidant/antioxidant parameters and mineral profile of summer anoestrous buffaloes may help to understand this problem of infertility.

Ovarian response and conception rate following oestrus synchronization using three protocols in Egyptian buffalo heifers

Objective: The aim of this study was to monitor the ovarian response and conception rate following estrous synchronization using CIDR, Ovsynch and double prostaglandin F2α protocols in Egyptian buffalo heifers. Material and methods: A total of 80 cyclic buffalo heifers were divided into four equal groups: CIDR (intravaginal progesterone releasing device, EAZI-BREEDTM CIDR®), Ovsynch (GnRH, PGF2α, GnRH injections), PGF (double PGF2α doses) and control. Timed artificial insemination (TAI) was performed in all heifers. All animals were exa - mined using ultrasound and blood samples were collected for measurement of progesterone. Results: A new follicular wave occurred earlier in the Ovsynch and PGF groups than in the CIDR group (p < 0.05). The mean diameter of the ovulatory follicle was smaller in the CIDR group than in the Ovsynch and PGF groups (p < 0.05). The ovulation rate was 100% in the CIDR group, 75% in the Ovsynch group and 70% in the PGF group. In the control group a lower pregnancy rate (20%) was determined in than in the CIDR (35%), Ovsynch (40%) and PGF (35%) groups. Progesterone concentrations were numerically higher in pregnant heifers of the CIDR group but the difference was non-significantly compared to the Ovsynch, PGF and control groups (p > 0.05). Conclusion and clinical relevance: EAZIBREEDTM CIDR®, Ovsynch-based TAI and PGF protocols were effective in synchronizing oestrus and resulted in nearly similar pregnancy rates in Egyptian buffalo heifers.

Ovsynch Plus protocol improves ovarian response in anovular Murrah buffaloes in low-breeding season

The objective of the study was to evaluate the efficacy of ovarian response and pregnancy rate in anovular buffaloes following Ovsynch and Ovsynch Plus protocols. Buffaloes (n = 55) were divided into two groups: Ovsynch group (n = 26): GnRH (10 μg, GnRH1) on Day 0, PGF₂ α (25 mg) on Day 7, GnRH (10 μg, GnRH2) on Day 9; Ovsynch Plus group (n = 29): 500 IU equine chorionic gonadotropin (eCG) 72 hr (day -3) prior to Ovsynch protocol, followed by fixed timed artificial insemination (FTAI) 6 and 24 hr after GnRH2 injection in bot groups. Transrectal ultrasonography was performed daily, that is, from day 0 and -3 in Ovsynch and Ovsynch Plus group, respectively for ovarian response and pregnancy diagnosis at day 30 post-insemination. In Ovsynch Plus group, administration of eCG prior to GnRH1 increased (p < .001) the diameter (mm) of dominant follicle (DF) from 10.15 ± 0.26 to 12.23 ± 0.34 within 72 hr of treatment resulting higher ovulatory response to GnRH1. Ovulation after GnRH1 was higher (p < .01) in Ovsynch Plus group (96.6%) than Ovsynch group (61.5%). However, ovulation rate to GnRH2 was similar (p > .05) between groups (Ovsynch group: 76.9% vs. Ovsynch Plus group: 70.0%). Mean DF diameter (mm) that ovulated to both GnRHs was higher (p < .01) than non-ovulated counterparts in both groups (Ovsynch group: 10.80 ± 0.27 vs. 8.47 ± 0.53; Ovsynch Plus group: 11.99 ± 0.24 vs. 9.5 ± 0.63). Pregnancy was established in buffaloes which responded to both GnRHs, irrespective of groups, being higher (p = .52) in Ovsynch Plus group (34.5%) than Ovsynch group (23.1%), though non-significant. In summary, this study showed that eCG inclusion prior to Ovsynch regimen improves ovulatory response in anovular buffaloes during low-breeding season.

Ovulatory and fertility response using modified Heatsynch and Ovsynch protocols in the anovular Murrah buffalo (Bubalus bubalis)

We studied the effect of modified Heatsynch and Ovsynch protocols on the ovulatory response (OR), estrus induction rate (EIR) and conception rate (CR) in the anovular postpartum Murrah buffalo (n = 35). In the modified Heatsynch protocol (Group I; n = 12), buffaloes were given two GnRH at 2 h interval on treatment day 0, PGF (PGF2α) on day 7 and estradiol (E₂) 1 mg on day 8. Two FTAI were done at 20 h intervals after E₂ administration. In the modified Ovsynch protocol (Group II; n = 15), GnRH was given on day 0, 7 and 16 with a PGF on day 14. Two FTAI were done; one at last GnRH and the other 20 h later. Group III served as untreated negative control (n = 8). During the treatment, ovarian changes were monitored by transrectal ultrasonography and plasma progesterone (P₄) and E₂. Administration of two GnRH at 2 h interval neither increased the OR nor strengthened the subsequent P₄ priming. Interestingly, in group I, none of the buffalo ovulated to E₂ though the EIR was 100% indicating the occurrence of behavioral, but not ovulatory estrus. Administration of GnRH 7 day prior to the commencement of Ovsynch protocol (Group II) did not improve the CR (21.4%), though the OR was 71.4%. No significant difference was found in the diameter of largest follicle between the ovulated and non-ovulated buffalo in response to GnRH suggesting that follicle of ≥9.5 mm is necessary but not sufficient to induce ovulation in the anovular buffalo. In both the protocols, the plasma P₄ was higher on day 7 in those buffaloes that ovulated to GnRH. Buffaloes treated with modified Ovsynch regimens were 5.27 times more likely to become pregnant than modified Heatsynch protocol. It is concluded that modified Ovsynch protocol is superior to modified Heatsynch protocol in terms of OR and CR.

Estrus induction and fertility response following different treatment protocols in Murrah buffaloes under field conditions

Aim:

The aim of this study was to evaluate the efficacy of three different treatment protocols for estrus induction and conception rate in postpartum anestrus buffaloes during breeding season under field conditions.

Materials and Methods:

The 47 postpartum anestrus buffaloes of the 2^nd to 6^th parity were divided into three groups. Group 1 (n=16): Buffaloes received cosynch treatment, that is, buserelin acetate 10 µg on day 0 and 9, cloprostenol 500 µg on day 7 followed by fixed-time artificial insemination (FTAI) at the time of second buserelin acetate and 24 h later. Group 2 (n=15): Buffaloes received norgestomet ear implant subcutaneously for 9 days, estradiol benzoate 2 mg on the day of implant insertion (day 0), pregnant mare serum gonadotropin (PMSG) 400 IU and cloprostenol 500 µg on day 9 followed by AI at 48 and 72 h after implant removal. Group 3 (Cosynch-plus, n=16): Buffaloes received Cosynch protocol as per Group 1 except an additional injection of PMSG 400 IU (i.m.) was given 3 days before the start of protocol and FTAI done at the same time of Group 1. Pregnancy diagnosis was performed after 45 days of AI.

Results:

The estrus induction response following the treatment was 81.3%, 100%, and 93.7% in Group 1, 2, and 3, respectively. The buffaloes of Group 1, 2, and 3 expressed intense (38.4%, 60% and 46.6%, respectively) and moderate estrus (46.1%, 26.6%, and 40%, respectively). The conception rates in Group 1, 2, and 3, at FTAI and overall including subsequent estrus were 37.5% and 62.5%, 53.3%, and 66.6%, 56.3%, and 75%, respectively.

Conclusion:

All the three treatment protocols can be effectively used for induction of estrus with acceptable conception rate in postpartum anestrus buffaloes during breeding season under field conditions. However, Cosynch-plus (similar to Cosynch protocol except addition of PMSG, 400 IU 3 days before the start of first buserelin acetate administration) protocol results comparatively better pregnancy rate.

Nasal immunization with inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis for improving ovarian responses and fertility in cross-bred buffaloes

This study was conducted to determine the effect of immunization with inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on ovarian responses and fertility in cross-bred buffaloes. A total of 134 cross-bred buffaloes were divided into four groups: groups T1 (n = 34), T2 (n = 35) and T3 (n = 31) were nasal immunized twice a day with 10 ml of 1 × 10¹⁰  CFU/ml of the C501 (pVAX-asd-IS) vaccine for 5, 3 and 1 day, respectively. Group C (n = 34) was nasal immunized with 10 ml PBS for 5 days. All animals were immunized twice with an interval of 14 days and administered with 200 μg of a GnRH analogue on day 28, 0.5 mg PGF_2α on day 35 and 200 μg of the same GnRH analogue on day 37. TAI was performed at 18 and 24 hr after the second GnRH treatment. Fourteen days after primary immunization, C501 (pVAX-asd-IS) elicited significant immune responses, and anti-inhibin IgG antibody titres in group T1 were significantly higher (p < .01) than groups T3 and C. After the second GnRH treatment, the growth speed of the dominant follicles in group T1 was significantly faster (p < .05) than groups T3 and C. The number and diameter of large follicles (≥10 mm) as well as ovulatory follicles in group T1 were the greatest in all groups, resulting in a greater conception rate in buffaloes with positive anti-inhibin antibodies. These results demonstrate that immunization with the C501 (pVAX-asd-IS) vaccine, coupled with the Ovsynch protocol, could be used as an alternative approach to improve reproductive performance in cross-bred buffaloes.

The efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes

The aim of this study was to evaluate the efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes. A total of 158 crossbred buffaloes divided into four groups and were intramuscularly injected with 1×10(10) (T1, n=41), 1×10(9) (T2, n=37), 1×10(8) (T3, n=37) or 0 (C, n=43) CFU/ml bacteria delivered inhibin vaccine in 10ml PBS on day 0 and 14, respectively. All animals were administered with 1000 IU PMSG on day 28, 0.5mg PGF2α on day 30 and 200μg GnRH on day 32. The results showed buffaloes immunized with the bacteria delivered inhibin vaccine had significantly higher titers of anti-inhibin IgG antibody than control group (P<0.01). The number and diameter of large follicles (≥10mm) as well as ovulatory follicles in group T1 was significantly greater than group C (P<0.05). The growth speed of dominant follicles in group T1 was significantly faster than groups T3 and C (P<0.05), resulting in a greater conception rate in buffaloes with positive antibodies. These results demonstrate that immunization with the bacterial delivered inhibin vaccine, coupled with the estrus synchronization protocol, could be used as an alternative approach to improve fertility in crossbred buffaloes.

LH peak and ovulation after two different estrus synchronization treatments in buffalo cows in the daylight-lengthening period

The aim of this study was to determine the timing of ovulation in relation to the LH peak after synchronization using PRID or Ovsynch protocols, to assess the effects of the period of treatment on these parameters and to provide information concerning how to use the two main protocols for fixed-time artificial insemination in buffalo. Forty-eight lactating Italian Mediterranean buffalo cows were used. The buffaloes were treated in various periods as follows: February to March (n = 12 PRID, n = 12 Ovsynch), end of the breeding season, May to June (n = 12 PRID, n = 12 Ovsynch), beginning of low-breeding season according to Italian environmental conditions. To determine the LH, blood samples were taken at 4-hour intervals, starting 24 hours from PRID removal (PRID group) or 12 hours from (PGF2α) injection (Ovsynch group) up to 108 hours. The ovaries were monitored by transrectal ultrasonography to verify ovulation. The LH-ovulation interval was similar in both groups (30.10 ± 1.05 and 32.77 ± 1.15 hours, respectively, in PRID and Ovsynch group). In the PRID group, the timing of ovulation in relation to device removal was 76.83 ± 3.65 hours with a high level of variability among the animals. In the Ovsynch group, we observed a better synchronization of LH peaks and ovulations, and the timing of ovulation in relation to the last GnRH injection was 35.67 ± 1.15 hours. The percentage of animals reaching the LH peak and ovulation was lower (P ≤ 0.05) in May to June (respectively 75.0% and 54.1%) compared to February to March (respectively 95.8% and 83.3%), indicating a reduction of hypothalamus-pituitary responsiveness to the synchronization treatments in the daylight-lengthening period.

A review of recent developments in buffalo reproduction - a review

The buffalo is an important livestock resource in several countries of South Asia and the Mediterranean regions. However, reproductive efficiency is compromised due to known problems of biological and management origins, such as lack of animal selection and poor nutrition. Under optimal conditions puberty is attained at 15 to 18 months in river buffalo, 21 to 24 months in swamp buffalo and is influenced by genotype, nutrition, management and climate. However, under field conditions these values deteriorate up to a significant extant. To improve reproductive efficiency, several protocols of oestrus and ovulation synchronization have been adopted from their use in commercial cattle production. These protocols yield encouraging pregnancy rates of (30% to 50%), which are comparable to those achieved in buffaloes bred at natural oestrus. The use of sexed semen in buffalo heifers also showed promising pregnancy rates (50%) when compared with conventional non-sexed semen. Assisted reproductive technologies have been transferred and adapted to buffalo but the efficiency of these technologies are low. However, these latest technologies offer the opportunity to accelerate the genetic gain in the buffalo industry after improving the technology and reducing its cost. Most buffaloes are kept under the small holder farming system in developing countries. Hence, future research should focus on simple, adoptable and impact- oriented approaches which identify the factors determining low fertility and oestrus behaviour in this species. Furthermore, role of kisspeptin needs to be explored in buffalo.

Fertility response in postpartum anoestrus buffaloes (Bubalus bubalis) using modified Ovsynch based timed insemination protocols

BACKGROUND AND AIM

Suboestrus constitutes the largest factor responsible for poor reproductive efficiency in buffaloes. Therefore, oestrus synchronization (OS) and fixed-time artificial insemination (AI) is considered an alternative approach to enhance reproductive efficiency in buffaloes. Thus, the present study was carried out to study the efficacy of modified Ovsynch protocol with fixed time insemination in post-partum anoestrus buffaloes.

MATERIALS AND METHODS

Total 50 post-partum anoestrus dairy buffaloes were selected and randomly divided into 5 Groups, each comprising ten animals (n=10). Animals of Group I received buserelin acetate 10 μg(GnRH) at day 0 and 9, and prostaglandin F2α (PGF2α) at day 7; in Group II similar to Group I except double dose of Gn RH (20 μg) at day 0; in Group III, similar to Group I plus additional administration of insulin on day 0, 1 and 2; in Group IV, similar to Group II plus additional administration of insulin on day 0,1 and 2; in Group V similar to Group I except replacement of first Gn RH with insulin on day 0,1 and 2. Animal of all groups were inseminated at fixed time using frozen semen at 60 h and 72 h after PGF2α administration and confirmed for pregnancy at day 60 post-insemination.

RESULTS

The results revealed satisfactory and comparable synchronization of oestrus (60-80%) and conception rate (20-40%) among the various treatment groups in the present study. The better synchronization was observed in modified protocols. However, non-significantly higher conception rate was recorded in modified Ovsynch protocol (40% each in Group II-V) as compared to 20% in Group-I (p>0.05).

CONCLUSION

In this study comparatively higher OS and conception following insulin modified Ovsynch based timed AI protocols in post-partum anoestrus buffaloes was found satisfactory and comparable.

The endocrine changes, the timing of ovulation and the efficacy of the Doublesynch protocol in the Murrah buffalo (Bubalus bubalis)

Experiments were conducted to investigate (a) the timing of ovulation and the associated endocrine changes (progesterone, estrogen and LH) during estrous cycle and (b) the efficacy, with respect to the pregnancy rate, in cycling and anestrus in Murrah buffaloes subjected to the Doublesynch protocol during the low breeding season. In experiment 1, 10 cycling buffaloes were administered PGF(2α) on day 0 (without regard to the estrous cycle stage), GnRH on day 2, a second PGF(2α) injection on day 9, and a second GnRH injection on day 11. Transrectal palpation was performed at 2-h intervals after the first and second GnRH treatments until ovulation was detected or for upto 96 h. The plasma progesterone and total estrogen concentrations were determined in blood samples collected at daily intervals starting 2 days before the onset of the protocol and continued until the day of the second detected ovulation. The plasma LH and total estrogen concentrations were measured in blood samples collected at 30-min intervals for 8h following the first and second GnRH injections and thereafter at 2-h intervals until 2h after the detection of ovulation. Ovulation occurred in 9/10 buffaloes (90%) at 22.2 ± 1.2 h (mean ± S.E.M.; range 18.0-26.0 h) and 10/10 buffaloes (100%) at 23.2 ± 1.0 h (mean ± S.E.M.; range 20.0-28.0 h) after the first and second GnRH treatments, respectively. The peak LH concentrations of 99.8 ± 28.5 ng/ml (range 37.8-320.0 ng/ml) and 62.3 ± 11.9 ng/ml (range 20.9-143.9 ng/ml) occurred 2.1 ± 0.3 h (range 1.0-3.5 h) and 2.3 ± 0.3 h (range 0.5-3.0 h) after the first and second GnRH treatments, respectively. The total estrogen concentration gradually increased from the day of both the first and second PGF(2α) administrations until the LH peak (with great variability) and then gradually declined to the basal level, which was reached at the time ovulation was detected. In experiment 2, 10 cycling and 11 non-lactating anestrus buffaloes were subjected to the Doublesynch protocol with timed artificial insemination (TAI) 16 and 24 h after the second GnRH treatment, and 55 cycling buffaloes were inseminated after spontaneous estrus was detected (control group). The pregnancy rates were 60% using TAI on cycling buffaloes (experiments 1 and 2), 55% for anestrus buffaloes (experiment 2), and 27.3% for cycling buffaloes inseminated following spontaneous estrus. The overall pregnancy success rates after the Doublesynch protocol in both cycling and anestrus buffaloes increased by 30.8% compared to spontaneous estrus (58.1% vs. 27.3%). In conclusion, the Doublesynch protocol effectively synchronized ovulation twice (after the first and second GnRH treatments) irrespective of the stage of estrous cycle in Murrah buffaloes. The study also demonstrated that the Doublesynch protocol followed by TAI significantly (P<0.005) enhanced the pregnancy rate in cycling and anestrus buffaloes in comparison to untreated controls during the low breeding season.

Plasma progesterone, oestradiol-17β and total oestrogen profiles in relation to oestrous behaviour during induced ovulation in Murrah buffalo heifers

The objectives of this study were to establish the characteristics of oestrous behaviour in Ovsynch (induction of ovulation through administration of GnRH-PGF2-GnRH in a systemic manner on 0, seventh and ninth day respectively) and Ovsynch plus Norprolac (Quinagolide hydrochloride – an inhibitor of prolactin secretion) treated Murrah buffalo heifers and to determine the relationships between this behaviour and the plasma concentrations of oestradiol-17β (E2), total oestrogen, and progesterone. Oestrus was detected by visual observations of oestrus signs, per rectal examination of genitalia and bull parading thrice a day during treatment period. Among all the symptoms, it was observed that bull mounting of heifers in oestrus was highest. Examination of genital tracts per rectum revealed that the cervix was relaxed, uterus was turgid and ovaries had palpable follicle in animals with oestrus. The peak concentrations of E2 (10.81 ± 0.62 pg/ml) and total oestrogen (17.11 ± 1.21 pg/ml) occurred at 9.45 ± 0.85 and 9.64 ± 0.93 h after second GnRH administration, respectively, in Ovsynch treated animals. However, the peak levels of E2 (20.02 ± 2.87 pg/ml) and total oestrogen (32.71 ± 3.15 pg/ml) occurred at 10.18 ± 0.50 and 10.36 ± 0.75 h after second GnRH administration, respectively, in Ovsynch plus Norprolac treated animals. Plasma progesterone concentration was basal (0.20 ± 0.001 ng/ml) during the peri-oestrus period. The plasma progesterone concentration was the lowest on the day of oestrus and increased to register a peak on day 13 ± 2 of the cycle. Oestrous behaviour was positively correlated with the peak concentration of E2 (p < 0.001) and total oestrogen (p < 0.001) during the peri-oestrus period. Inhibition of prolactin by Norprolac administration significantly increased the concentration of E2 and total oestrogen during oestrus in buffaloes in comparison to those recorded in animals subjected to Ovsynch protocol alone. In conclusion, our results suggest that the peak concentrations of E2 and total oestrogen and mean level of E2 and total oestrogen during the peri-oestrus period are the important factors contributing the behavioural manifestation of oestrus in buffalo cows.

Reproductive cycles of buffalo

The domestic water buffalo (Bubalus bubalis) has an important role in the agricultural economy of many developing countries in Asia, providing milk, meat and draught power. It is also used in some Mediterranean and Latin American countries as a source of milk and meat for specialized markets. Although the buffalo can adapt to harsh environments and live on poor quality forage, reproductive efficiency is often compromised by such conditions, resulting in late sexual maturity, long postpartum anoestrus, poor expression of oestrus, poor conception rates and long calving intervals. The age at puberty is influenced by genotype, nutrition, management and climate, and under favourable conditions occurs at 15-18 months in river buffalo and 21-24 months in swamp buffalo. The ovaries are smaller than in cattle and contain fewer primordial follicles. Buffalo are capable of breeding throughout the year, but in many countries a seasonal pattern of ovarian activity occurs. This is attributed in tropical regions to changes in rainfall resulting in feed availability or to temperature stress resulting in elevated prolactin secretion, and in temperate regions to changes in photoperiod and melatonin secretion. The mean length of the oestrous cycle is 21 days, with greater variation than observed in cattle. The signs of oestrus in buffalo are less overt than in cattle and homosexual behaviour between females is rare. The duration of oestrus is 5-27 h, with ovulation occurring 24-48 h (mean 34 h) after the onset of oestrus. The hormonal changes occurring in peripheral circulation are similar to those observed in cattle, but the peak concentrations of progesterone and oestradiol-17β are less. The number of follicular waves during an oestrous cycle varies from one to three and influences the length of the luteal phase as well as the inter-ovulatory interval. Under optimal conditions, dairy types managed with limited or no suckling resume oestrus cyclicity by 30-60 days after calving, while swamp types with free suckling do so at 60-90 days. However, in many farming systems prolonged postpartum anoestrus is a major problem, and the causes include poor nutrition and body condition, and stress due to harsh climates and improper management. Synchronization of time or induction of oestrus can be done using the same regimens as applied in cattle, using various combinations of prostaglandins, progesterone releasing devices, GnRH and eCG, but success rate is poor when treatment is done during the periods of marginal breeding activity or seasonal anoestrus.

Reproduction in domestic buffalo

The domestic buffalo is an indispensable livestock resource to millions of smallholder farmers in developing countries, particularly in Asia. Although its reproductive biology is basically similar to that of cattle, there are important differences and unique characteristics that need to be considered in order to apply modern reproductive technologies to improve its productivity. Under most smallholder production systems, the reproductive efficiency of buffalo is compromised by factors related to climate, management, nutrition and diseases. However, when managed and fed properly, buffalo can have good fertility and provide milk, calves and draught power over a long productive life. The basic technical problems associated with artificial insemination in buffalo were largely overcome two decades ago, but the technology has not had the expected impact in some developing countries, because largely of infrastructural and logistic problems. Approaches involving the use of hormones for treating anoestrus and for synchronizing oestrus have had varying rates of success, depending on the protocols used and the incidence of underlying problems that cause infertility. Embryo technologies such as multiple ovulation embryo transfer, in vitro embryo production, cryopreservation and cloning are being intensively studied but have had far lower success rates than in cattle. Improving the productivity of buffalo requires an understanding of their potential and limitations under each farming system, development of simple intervention strategies to ameliorate deficiencies in management, nutrition and healthcare, followed by judicious application of reproductive technologies that are sustainable with the resources available to buffalo farmers.

Effect of oestrus synchronization methods on oestrus behaviour, timing of ovulation and pregnancy rate during the breeding and low breeding seasons in Nili-Ravi buffaloes

The objective of this study was to determine the effect of oestrous synchronization methods on oestrous behaviour, timing of ovulation and pregnancy rate during the breeding and low breeding seasons in Nili-Ravi buffaloes. In Experiment 1, oestrous behaviour and timing of ovulation were determined from (n=34) oestruses. The mean (+/- S.E.M.) time of ovulation after the onset of standing oestrus was greater (P<0.05) in PGF(2alpha)-induced luteolysis (30.6+/-1.5h) compared to Ovsynch buffaloes (15.0+/-0.8h). In Experiment 2, pregnancy rates were compared between two methods of synchronization (detected oestrus and Ovsynch protocol) during the breeding and low breeding seasons. Pregnancy rates of buffaloes bred at detected oestrus (62.5%) or by the Ovsynch protocol (36.3%) during the breeding season did not differ significantly (P>0.05) from those which were inseminated during the low breeding season (55.5%) and (30.4%), respectively. This study demonstrates clearly that (1) timing of ovulation in Nili-Ravi buffalo is about 30h after the onset of standing oestrus and (2) buffaloes can be successfully synchronized with optimum fertility using either PGF(2alpha) alone (detected oestrus) or using (Ovsynch protocol) during low breeding season, to calve during the period when milk availability is short.

Efficacy of Heatsynch protocol for induction of estrus, synchronization of ovulation and timed artificial insemination in yaks (Poephagus grunniens L.)

The objective of this study was to test the efficacy of induction of estrus, synchronization of ovulation and timed artificial insemination in anestrous yaks using the Heatsynch protocol. In Experiment 1, 10 anestrous yaks were administered an analogue of gonadotropin releasing hormone (GnRH) followed by prostaglandin (PG)F2alpha 7 days later and then estradiol cyponate (ECP) 24 h after that. Ovulation was detected by rectal palpation at 2h intervals beginning at the initial signs of estrus. Blood samples were collected at 2h intervals beginning at the time of ECP injection up to 2h after the occurrence of ovulation for the determination of LH and progesterone. All the animals responded to the Heatsynch protocol with expression of estrus and synchronization of ovulation. The mean time interval from the ECP injection to ovulation was 59.4+/-2.62 h (range 50-72 h). The interval from the LH peak to ovulation was 30.2+/-2.3 h. The high degree of synchrony in ovulation could be attributed to the synchrony in the timing of LH peaks. In Experiment 2, 10 anestrous yaks were treated with the Heatsynch protocol (as in Experiment 1) and TAI was performed at 48 and 60 h after the ECP treatment. Concurrently, 16 cycling yaks were inseminated approximately 12 h after detection of spontaneous estrus. Pregnancy rates were similar in both groups, 40% for TAI and 43.75% for yaks inseminated following spontaneous estrus (p>0.05). From this study, two conclusions can be drawn. First, the Heatsynch protocol can be successfully used to induce and synchronize estrus in anestrous yaks and, second, ovulation following the Heatsynch protocol is synchronized adequately to permit the use of fixed time AI in this species.

Pregnancy and calving rates following transfer of in-vitro-produced river and F1 (river x swamp) buffalo (Bubalus bubalis) embryos in recipients on natural oestrus or synchronised for ovulation

The main objective of this study was to compare pregnancy and calving rates following transfer of in-vitro-produced fresh river and F1 (river x swamp) buffalo embryos in recipients synchronised by Ovsynch protocol or following natural oestrus. River embryos were produced from cumulus-oocyte complexes (COCs) derived by ovum pick up (OPU) on 40 Murrah and Nili-Ravi donor buffaloes over a twice-weekly collection schedule for 120 single OPUs. F1 embryos were produced by fertilisation of swamp COCs recovered from abattoir ovaries coincubated with river sperm cells. Both groups of embryos were produced following the same protocol for in vitro production. With regard to the OPU source of COCs, 923 antral follicles were punctured and 647 COCs were recovered (70%). From 462 selected COCs for IVM, 257 (55.6%) cleaved zygotes were recorded leading to 93 blastocysts (20.1%). In total, 590 swamp COCs were aspirated from abattoir ovaries and 476 were selected for IVM leading to 270 (56.7%) cleaved zygotes and resulting in 137 blastocysts (28.8%). River and F1 embryos were transferred between Day 6 to 7 of in vitro development, corresponding to blastocyst-expanding blastocyst, into F1 recipients synchronised by Ovsynch and swamp buffaloes following natural oestrus, respectively, each of them receiving two embryos. According to palpation per rectum of the ovaries at the time of embryo transfer, 26 of the 47 (55.3%) F1 recipients synchronised by Ovsynch were considered suitable for transfer, resulting in seven pregnancies (26.9%) and four calvings (15.3%) owing to three abortions occurring between 2 and 3 months of pregnancy. In total, 29 swamp recipients following natural oestrus were judged suitable as recipients, resulting in 12 pregnancies (41.4%) and 10 calvings (34.5%) owing to two abortions at 2 and 3 months of gestation respectively. Pregnancy and calving rates following transfer of river and F1 embryos were similar. Likewise, weight at birth of calves derived from transfer of river and F1 embryos was not different: 30.5 +/- 1.4 and 32.9 +/- 2.4 respectively. Pregnancy and calving rates following AI in a group of river and swamp buffaloes considered for reference in this study were similar to recipients carrying in-vitro-produced embryos. Collectively, no apparent postnatal complications were recorded in resulting live calves.

Reproduction in the Water Buffalo

In this paper, an account of various aspects related to buffalo reproduction are given. Fundamental concepts of the reproductive physiology as well as manipulation of the reproductive function will be presented. This will include an overview of the most recent developments of the oestrous cycle and the ovulation control, new strategies of reproductive management for the improvement of genetic gain and the application of newly developed reproductive technologies, such as in vitro embryo production, embryo and sperm sexing and cloning.

Seasonal variation and circadian rhythmicity of the prolactin profile during the summer months in repeat-breeding Murrah buffalo heifers

The present study was undertaken to determine a detailed endocrine profile for prolactin and progesterone during the oestrous cycle in repeat-breeding Murrah buffalo heifers during summer and winter. Hormone concentrations were quantified in blood plasma samples collected over the oestrous cycle in both winter and summer, as well as in samples collected during the summer months to observe circadian rhythmicity. The mean plasma prolactin concentration during the winter months ranged from 3.10 +/- 0.48 to 9.17 +/- 1.39 ng mL(-1); during the summer months, plasma prolactin concentrations ranged from 248.50 +/- 16.03 to 369.63 +/- 25.13 ng mL(-1). During the winter months, the mean plasma progesterone concentration ranged from 0.20 +/- 0.00 to 3.04 +/- 0.34 ng mL(-1), which was significantly higher (P < 0.01) than the prolactin concentrations recorded in the summer months (range 0.20 +/- 0.00 to 1.48 +/- 0.13 ng mL(-1)). Plasma prolactin and progesterone concentrations were negatively correlated (r = -0.24) during the summer oestrous cycle, which indicates prolactin-induced suppression of progesterone secretion through poor luteal development. During the summer, a circadian rhythmicity was observed in buffaloes and the results indicate that high prolactin secretion contributes to poor fertility by lowering gonadal hormone (progesterone) secretion. It was concluded from the present study that prolactin and progesterone profiles during the summer and winter months are directly correlated with the reproductive performance of buffaloes. The finding also validates the hypothesis that hyperprolactinaemia may cause acyclicity/infertility in buffaloes during the summer months due to severe heat stress.

Advanced reproductive technology in the water buffalo

Embryo transfer techniques in water buffalo were derived from those in cattle. However, the success rate is much lower in buffaloes, due to their inherent lower fertility and poor superovulatory response. The buffalo ovary has a smaller population of recruitable follicles at any given time than the ovary of the cow (89% fewer at birth). In addition, estrus detection is problematic. Progress in the field of embryo transfer in water buffalo has been slow, and is primarily due to a poor response to superovulation. The average yield of transferable embryos is less than one per superovulated donor. In vitro embryo production could considerably improve the efficacy and logistics of embryo production. The technique of Ovum Pick Up is superior to superovulation; it can yield more transferable embryos per donor on a monthly basis (2.0 versus 0.6). The feasibility of intergeneric embryo transfer between buffalo and cattle has been investigated. No pregnancy resulted after transfer of 13 buffalo embryos to synchronized Holstein heifers. Preliminary successes with nucleus transfer of Bubalus bubalis fetal and adult somatic nuclei into enucleated bovine oocytes and subsequent development to the blastocyst stage have been reported.

Ovarian dynamics and milk progesterone concentrations in cycling and non-cycling buffalo-cows (Bubalus bubalis) during Ovsynch program

The objective was to evaluate ovarian dynamics and progesterone concentrations in cyclic (CYC, n=10) and non-cyclic (NCY, n=8) buffalo-cows during Ovsynch program. All cows received GnRH on day 0, PGF2alpha on day 7, and GnRH on day 9, and AI 14 h later. Ovarian structures were monitored by ultrasound and milk samples were collected for progesterone (P4) analysis. The first GnRH resulted in ovulation in CYC (90%) and NCY (62.5%) cows. By day 7, almost all cows had large follicle and lutein tissue. Luteolytic responses to PGF2alpha were 80 and 87.5% for CYC and NCY cows, respectively. Following second GnRH, ovulation occurred in 80% of CYC and 100% of NCY cows. Ovulation began earlier (12 h following second GnRH) and extended for longer (36 h) in NCY cows, when compared to CYC cows (36 and 12 h, respectively). The mean P4 levels increased from days 0 through 7 in CYC and NCY cows and levels were higher in CYC group. Conception rates were 60 and 37.5% in CYC and NYC cows, respectively. Early and asynchronous ovulation and luteal sub-function seemed to be a problem in NCY cows. Inseminating NCY cows twice, at 0 and 24 h of the second GnRH is recommended.

A sensitive sandwich ELISA for buffalo prolactin

Two murine monoclonal antibodies have been developed against the buffalo prolactin (buPRL). These were designated as 1501 and 1504. Using two MAbs and anti-buPRL rabbit serum, an analysis was performed for the development of a sandwich ELISA (sELISA). The 1504/buPRL/anti-buPRL rabbit serum system was found feasible for sELISA. The sELISA had a sensitivity of 156 pg/mL. The buffalo serum sample showed a parallelism with the standard curve. The intra- and inter-assay coefficients of variance were 8.4% and 9.06%, respectively. These data proved the validity of the assay.

Protocols for synchronizing estrus and ovulation in buffalo (Bubalus bubalis): a review

Poor estrus expression and a prolonged intercalving interval compromise the reproductive efficiency of female buffaloes. These limitations are exacerbated during the hot season, when fertility decreases dramatically. Pregnancy rate decrease further because difficulties in detecting estrus. To improve reproductive efficiency, several protocols of estrus and ovulation synchronization have been developed. These procedures are based on manipulating the CL, either to induce premature luteolysis using prostaglandins or to prolong the luteal phase using progestagens. However, it has recently emerged that a more precise manipulation of follicular development may be needed to achieve better synchrony of ovulation and improve fertility. Researchers have therefore turned their attention to evaluating programs in which hormones such as GnRH, FSH, LH, eCG, hCG, prostaglandins, progesterone and estradiol are administered. This review considers the impacts of estrus and ovulation synchronization protocols on fertility in the buffalo. In general, it may be stated that buffaloes respond well to the exogenous administration of hormones, and artificial insemination is possible at a pre-established time after synchronizing ovulation. Most combined hormone protocols give satisfactory pregnancy rates, comparable to those achieved in animals inseminated at natural estrus.