Effects of using vasectomized bulls in artificial insemination practice on the reproductive efficiency of Italian buffalo cows

Biostimulation and pheromones in livestock: A review

This review examines aspects of the phenomenon of biostimulation in swine, goats, sheep, cattle and deer, to improve the collective knowledge and exploitation of its relevant mechanisms and effects in animal production. The long-term goal is to implement biostimulation strategies that benefit livestock reproduction and production while being both cost-effective and socially acceptable.

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.

Milk yield at first lactation, parity, and season of calving affect the reproductive performance of water buffalo cows

Context Profitability of water buffalo systems depends on a calving interval (CI) <400 days. Several factors affect the achievement of this target. However, milk yield at first lactation has received little attention. Aims Determine the effect of milk yield at first lactation, parity, season of calving and farm, on the length of CI and the probability of a CI ≤ 400 days in water buffaloes. Methods A retrospective analysis of milk yield at first lactation and reproductive records of 1459 water buffaloes was carried out. Milk yield was categorised as Group 1 (≤1090 kg), Group 2 (1090–1377 kg), Group 3 (1377–1684 kg) and Group 4 (>1684 kg); parity was categorised as parity 1, 2 and ≥ 3; and month of calving was grouped into three seasons: December–March, April–July, and August–November. Data were analysed using linear and logistic mixed models. Key results CI increased from 425.3 days (95% CI: 418.8–431.8 days) in group 1 to 463.3 days (95% CI: 456–470.6 days) in group 4 (P < 0.05), while the probability of having a CI ≤ 400 days decreased from 0.5 (95% CI: 0.46–0.54) to 0.26 (95% CI: 0.22–0.29), respectively (P < 0.05). CI decreased from 466 days (95% CI: 460.8–471.3 days) in parity 1 to 410.5 days (95% CI: 405.2–415.8 days) in parity ≥3, whereas the probability of a CI ≤ 400 days increased from 0.26 (95% CI: 0.24–0.29) to 0.51 (95% CI: 0.47–0.54) respectively (P < 0.05). Water buffaloes calving in August–November showed significantly shorter CI and, along with those calving between December–March, showed the highest probability of a CI ≤ 400 days. An interaction between milk yield at first lactation and parity on both outcomes was observed. Conclusions Shorter CI and higher probability of a CI <400 days were associated with lower milk yields at first lactation, higher parity and calving between August–November. Higher milk yield at first lactation affected negatively the reproductive performance of water buffaloes, especially at parity 1 and 2. Implications These results highlight the importance of adequate nutritional management to allow water buffaloes to cope with the challenge of the postpartum negative energy balance and have a calving interval less than 400 days.

Effect of live body weight and method of synchronization on ovulation, pregnancy rate and embryo and fetal loss in buffalo heifers

This study aimed to assess the influence of live body weight (LBW) and age on reproductive performance in buffalo heifers synchronized by different treatments. The study was carried out on 146 Mediterranean buffalo heifers (mean age 25.3±13.4 months, LBW 424±47 kg), divided into 2 homogeneous groups and synchronized by Ovsynch-TAI Program (OVS; n = 72) or double prostaglandin administered 12 days apart (PGF; n = 74). All the buffaloes were inseminated twice and follicle dimensions and ovulation rate (OR) were assessed by ultrasound 24 and 48 h post-insemination. Pregnancy was assessed on day 25, 45 and 90 post-insemination and the incidence of late embryonic (LEM) and fetal (FM) mortality were respectively recorded. Data were analyzed by ANOVA, Chi-square test and multiple logistic regression. The LBW was significantly (P<0.05) higher in inseminated animals, compared to those that did not respond to the treatments (450.0±3.2 vs. 423.2±9.6 kg in inseminated and not inseminated heifers, respectively). Total OR was similar between groups, although OR at 24 h tended to be higher (P = 0.06) in OVS (86.7 vs. 72.9% in OVS and PGF, respectively). A (P<0.01) higher LBW was observed in ovulated heifers of PGF, while no differences were recorded in OVS. LBW affected OR (odds ratio = 1,032; P<0.05) only in PGF, while no effects were recorded in OVS. Total pregnancy rate, LEM and FM were similar between groups. In conclusion, the LBW would be considered before including buffalo heifers in a synchronization program and both synchronization treatments can be useful.

Effects of reproductive season on embryo development in the buffalo

Interest in buffalo farming is increasing worldwide due to the critical role played by buffaloes as sources of animal protein in tropical and subtropical environments. However, reproductive seasonality negatively affects the profitability of buffalo farming. Buffaloes tend to be short-day breeders, with seasonality patterns increasing with greater distances from the Equator. Although ovarian cyclic activity may occur throughout the year, seasonal anoestrus and cycles in calving and milk production are recorded. When buffaloes are forced to mate during the unfavourable season, to meet market demand, they may undergo a higher incidence of embryo mortality. This review addresses the effects of the reproductive season on embryo development in the buffalo, analysing the different factors involved in determining embryo mortality during the unfavourable season, such as impaired luteal function, oocyte competence and sperm quality. The review then focuses on strategies to control the photoperiod-dependent annual fluctuations in conception and embryo mortality in the female buffalo.

Effect of mastitis on luteal function and pregnancy rates in buffaloes

The aim of this study was to investigate the effects of mastitis on CL development and function and pregnancy rate in buffaloes. Sixty-six buffaloes (Bubalus bubalus) reared in a commercial farm at El-Beheira governorate, north of Egypt were used in this study. According to the visual observation of milk, physical examination of the udder and actual somatic cell count in milk, buffalo cows were divided into three groups: without mastitis (W), n = 23; subclinical mastitis (SC), n = 18; and clinical mastitis (C), n = 25. All buffalo cows were synchronized by double dose of PGF2α (11-day interval) and inseminated by frozen-thawed semen of fertile bull. Mean CL diameter was ultrasonically examined on Days 5, 9, 12, 16, 21, and 25 after artificial insemination (AI). Blood samples were taken on the days of ultrasonography for progesterone (P4) assay. Results indicated that pregnancy rates were lower (P < 0.05) in C (28.00%) and SC (55.56%) compared with W (69.57%) on Day 25 after first AI. Pregnancy rates reduced to 60.87%, 44.45%, and 16.00% in W, SC, and C, respectively, at Day 45 after insemination. Thus, the embryonic loss was 8.7%, 11.11%, and 12.00 % in W, SC, and C cows, respectively. Pregnancy rates decreased between 44.32% and 50.51% when mastitis occurred during Day -15 before to Day +30 after AI, compared with 59.22% in the uninfected cows. The diameter of CL was greater (P < 0.05) in W than SC and C cows starting at Day 9 postbreeding onward. Likewise, P4 concentrations on Days 9 through 25 after AI were greater (P < 0.05) in W cows as compared to SC and C cows. Positive correlations (P < 0.01) were found on Days 5, 9, 12, 16, 21, and 25 after AI between CL diameter and P4 concentrations. Similar trend was found among CL diameter, P4 concentrations, and pregnancy rate. Accordingly, incidence of mastitis revealed suppression to both CL diameter and function leading to significant reduction in pregnancy outcome of buffalo cows.

Ovarian responses of dairy buffalo cows to timed artificial insemination protocol, using new or used progesterone devices, during the breeding season (autumn-winter)

This study evaluated the effect of new or used P4 devices on the ovarian responses of dairy buffalo that were administered an estradiol (E2) plus progesterone (P4)-based timed artificial insemination (TAI) protocol during the breeding season. On the first day of the TAI protocol, 142 cows were randomly assigned to receive one of the following: a new device (New; 1.0 g of P4; n = 48); a device that had previously been used for 9 days (Used1x, n = 47); or a device that had previously been used for 18 days (Used2x, n = 47). Ultrasound was used to evaluate the following: the presence of a corpus luteum (CL); the diameter of the dominant follicle (ØDF) during protocol; ovulatory response; and pregnancies per AI (P/AI). Despite similar responses among the treatments, there was a significant positive association of the ØDF during TAI protocol with ovulatory responses and number of pregnancies. In conclusion, satisfactory ovarian responses and a satisfactory pregnancy rate were achieved when grazing dairy buffalo were subjected to the TAI protocol in breeding season, independent of whether a new or used P4 device was used. Furthermore, the presence of the larger follicle was associated with a higher ovulation rate and higher P/AI following TAI.

Use of a domestic Korean black goat (Capra hircus coreanae) with its chest crayon-harnessed in detecting estrus of Himalayan tahrs (Hemitragus jemlahicus)

The reliability of a Korean black goat (Capra hircus coreanae) to detect estrus in Himalayan tahrs (Hemitragus jemlahicus) for an artificial breeding program was investigated. Estrus in six female Himalayan tahrs was synchronized using fluorogestone acetate (FGA) sponges. Thirteen days later, 200 IU of PMSG and 100 IU of hCG were injected before removing the sponges and simultaneously injecting 5 mg of PGF2α the next day. Penetration of the cervical canal and the thickness and location of red crayon marks were examined 40~43 h later. Two females treated with sponges containing 60 or 45 mg of FGA had estrogen levels of 8.7 and 11.1 pg/mL, respectively. No red marks were found on the backs of these two tahrs. The remaining females had higher levels of estradiol, and the red crayon marks were clearly shown. The cervical folds of these tahrs were readily penetrated and the insemination gun was smoothly inserted into the uterine body. In conclusion, a Korean domestic goat with its chest crayon-harnessed was successfully used to detect estrus of Himalayan tahrs. This technique might be utilized as a part of breeding programs for wild goats and avoid the need for a vasectomy of conspecific males.

Influence of season on corpus luteum structure and function and AI outcome 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 ± 0.3 and 3.4 ± 0.2, respectively) than during the transition period (1.6 ± 0.12 and 1.8 ± 0.2, 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 ± 1.5) than in the transitional period (8.3 ± 0.7). 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.

The effect of season on oocyte quality and developmental competence in Italian Mediterranean buffaloes (Bubalus bubalis)

At Italian latitudes, buffalo (Bubalus bubalis) is a seasonally polyestrous species, showing an improved reproductive efficiency when daylight decreases (autumn). The aim of the present study was to evaluate the influence of the season on buffalo oocyte recovery rate, on oocyte quality, assessed on morphological basis, and developmental competence after in vitro fertilization. For this purpose, buffalo ovaries were collected from a local abattoir and the oocytes obtained by aspirating the follicles were evaluated, classified and, if considered of good quality, devolved to the different procedures of IVEP. In general, no differences were found in terms of oocyte recovery per ovary among seasons, but interestingly, the percentage of small oocytes was higher (P<0.05) during spring and summer (0.9±0.1 and 0.9±0.2) compared to autumn and winter (0.3±0.1 and 0.2±0.1). Both cleavage and embryo rate increased during the period from October to December (71.7±3.1 and 26.5±2.1, respectively) compared to the period from April to June (58.0±2.4 and 18.8±1.6, respectively), thus reflecting the in vivo reproductive behavior. Nevertheless, it is worth emphasizing that transferrable embryos were produced in vitro, even during the unfavorable season, but with decreased efficiency. In conclusion, these results suggest to avoid the oocyte collection during spring when planning OPU trials in order to save resources and improve the benefits/costs ratio.

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.

Bubaline versus bovine reproduction

Fertility in water buffalo (Bubalus bubalis) is considerably lower than that in cattle (Bos taurus and Bos indicus). Poor breeding efficiency is attributed to late onset of puberty, seasonality, poor estrus expression, and long calving intervals. Accurate estrus detection is a prerequisite for efficient reproductive management. Established reproductive management techniques in cattle can be successfully applied to water buffalo because of the similarities in the anatomy, physiology, and endocrinology of reproduction between the two genera.

Importation of in vitro-produced Bubalus bubalis embryos from Italy into the United States: a case report

On December 19, 2005, 14 in vitro-fertilized water buffalo (Bubalus bubalis) embryos, which had been cryopreserved by vitrification, were thawed and transferred into B. bubalis recipients in California. The embryos had been produced in Italy, following transvaginal oocyte pickup (TVOPU), with subsequent in vitro maturation, insemination, and culture. This case study relates our experience in meeting the regulatory criteria, established by the Animal Import/Export Office of the USDA-Animal and Plant Health Inspection Service (USDA-APHIS), in order to successfully import these embryos into the USA.

Embryonic mortality in buffaloes synchronized and mated by AI during the seasonal decline in reproductive function

The aim was to determine the factors that contribute to embryonic mortality in buffaloes mated by AI during a period of increasing day length which corresponds to a natural decline in reproductive activity. Italian Mediterranean buffalo cows (n=243) showing regular estrous cycles were synchronized using the Ovsynch-TAI program and mated by AI at 16 and 40 h after the second injection of GnRH. Blood samples were collected on Days 10 and 20 after the first AI and assayed for progesterone (P4). Pregnancy diagnosis was undertaken on Days 26 and 40 after the first AI using rectal ultrasonography. Buffaloes with a conceptus on Day 26 but not on Day 40 were judged to have undergone embryonic mortality and for these animals uterine fluid was recovered by flushing and analysed for common infectious agents. Estrus synchronization was achieved in 86% of buffaloes and the pregnancy rate on Day 40 was 34%. Embryonic mortality between Days 26 and 40 occurred in 45% of buffaloes and was associated with the presence of significant infectious agents in only 10 buffaloes (8%). Concentrations of P4 on Day 10 after AI were higher (P<0.05) in buffaloes that established a pregnancy than in buffaloes that showed embryonic mortality that was not associated with infectious agents. Similarly, on Day 20 after AI P4 concentrations were higher (P<0.01) in pregnant buffaloes compared with non-pregnant buffaloes and buffaloes that had embryonic mortality. It is concluded that a reduced capacity for P4 secretion can explain around 50% of embryonic mortalities in buffaloes synchronised and mated by AI during a period of low reproductive activity and that other as yet unidentified factors also have a significant effect on embryonic survival.

First Established Pregnancies in Mediterranean Italian Buffaloes (Bubalus bubalis) Following Deposition of Sexed Spermatozoa near the Utero Tubal Junction

At the time of AI following Ovsynch protocol, a total of 51 buffaloes were randomly divided in a first group (n = 30) subjected to conventional AI into the uterine body with 20 million non-sex sorted frozen-thawed spermatozoa, while a second group (n = 21) was inseminated near the utero-tubal junction (UTJ) ipsilateral to the ovary carrying the preovulatory follicle with 2.5 million live (4 million total) sex-sorted frozen-thawed spermatozoa. The semen used for flowcytometric sorting was collected and processed on a farm in Italy, and then shipped to a laboratory in Germany. Eleven buffaloes were inseminated with X-chromosome bearing spermatozoa and 10 with Y-chromosome bearing spermatozoa. Conception rates after conventional and UTJ inseminations were 43.3% (n = 13) and 42.8% (n = 9) respectively (p = 0.97). Eight of the nine foetuses obtained after insemination with sexed spermatozoa corresponded to the sex as predicted by the cell sorting procedure (five male and four female foetuses by ultrasound vs six male and three female foetuses by cell sorting). In conclusion, for the first time buffalo semen has been successfully subjected to procedures for flowcytometric sperm sorting and freezing. Low doses of sexed spermatozoa have been deposited near the UTJ giving conception rates similar to those of conventional AI with full dose.

Comparison of pregnancy rates with two estrus synchronization protocols in Italian Mediterranean Buffalo cows

The aim in this study was to compare two estrus synchronization protocols in buffaloes. Animals were divided into two groups: Group A (n=111) received 100 microg GnRH on Day 0, 375 microg PGF(2alpha) on Day 7 and 100 microg GnRH on Day 9 (Ovsynch); Group B (n=117) received an intravaginal drug release device (PRID) containing 1.55 g progesterone and a capsule with 10mg estradiol benzoate for 10 days and were treated with a luteolytic dose of PGF(2alpha) and 1000 IU PMSG at the time of PRID withdrawal. Animals were inseminated twice 18 and 42 h after the second injection of GnRH (Group A) and 60 and 84 h after PGF(2alpha) and PMSG injections (Group B). Progesterone (P(4)) concentrations in milk samples collected 12 and 2 days before treatments were used to determine cyclic and non-cyclic buffaloes, and milk P(4) concentrations 10 days after Artificial insemination (AI) were used as an index of a functional corpus luteum. Cows were palpated per rectum at 40 and 90 days after AI to determine pregnancies. All previously non-cyclic animals in Group B had elevated P(4) (>120 pg/ml milk whey) on Day 10 after AI. Accordingly, a greater (P<0.01) relative percentage of animals with elevated P(4) 10 days after AI were observed in Group B (93.2%) than in Group A (81.1%). However, there was no difference in overall pregnancy rates between the two estrus synchronization protocols (Group A, 36.0%; Group B 28.2%). When only animals with elevated P(4) on Day 10 after AI were considered, pregnancy rate was higher (P<0.05) for animals in Group A (44.4%) than Group B (30.3%). The findings indicated that treatment with PRID can induce ovulation in non-cyclic buffalo cows. However, synchronization of estrus with Ovsynch resulted in a higher pregnancy rate compared with synchronization with PRID, particularly in cyclic buffalo.

Bovine and buffalo in vitro embryo production using oocytes derived from abattoir ovaries or collected by transvaginal follicle aspiration

This study was undertaken in order to evaluate the effect of oocyte source (live animals and abattoir ovaries) on subsequent embryo development in buffalo (Bubalus bubalis). Cow ovaries were also collected as oocyte donors for in vitro embryo production (IVEP). Three hundred thirty-eight oocytes were recovered by ovum pick up (OPU, Group A) from 8 pluriparous buffalo cows, while 1127 and 1457 oocytes were aspirated, respectively, from buffalo (Group B) and bovine (Group C) slaughterhouse ovaries. Cumulus enclosed oocytes (COCs) suitable for IVEP were in vitro matured (IVM), fertilized (IVF) and cultured (IVC) to the tight morula (Tm) and blastocyst (Bl) stage. Within buffalo species Group A had a higher Bl yield (29.7 % versus 19.9%; P<0.05) and a lower proportion of embryos arrested at Tm stage (11.1% versus 22.3%; P<0.05) than Group B. Within slaughterhouse groups cattle oocytes had a higher cleavage rate (83.9% versus 64.8%; P<0.05) and yielded 49.2% more blastocysts than buffalo. However, when data are related to the total number of cleaved oocytes, only 13.7% more blastocysts were produced in cattle than in buffalo.In conclusion, in buffalo species the source of oocytes significantly affected post-fertilization embryo development, as demonstrated by the higher Bl yields derived from OPU-derived oocytes.A higher overall IVEP efficiency, mainly related to the higher cleavage rate, was recorded in cattle compared with buffalo when ovaries from an abattoir were used as oocyte donors.

In vitro embryo production in buffalo species: state of the art

In the last several years, there has been an increasing interest in in vitro embryo production (IVEP) technologies for faster propagation of superior germplasm in buffalo because of the low efficiency of superovulation (SO) and embryo transfer (ET) programs in this species. Although the IVEP efficiency has improved, embryo yield and development to term are still very low. This paper reviews the progress made in optimizing the IVM, IVF, and IVC systems. It also highlights the importance of embryo cryopreservation, which might critically contribute to the diffusion of ET procedures in the field. The acquisition of more information on embryo physiology, metabolism, and culture requirements in this species is critical to optimize the efficiency of advanced reproductive strategies. Further studies are also needed to improve the cryopreservation of IVEP embryos. The second part of the work underlines the potential impact of ovum pick-up (OPU) technique combined with IVEP on genetic improvement of buffalos. The OPU technique is a non-invasive and repeatable procedure for recovering large numbers of meiotically competent oocytes from antral follicles of live animals. Our experience, in buffalo, has demonstrated that OPU is superior to SO because it can yield more transferable embryos (TE) per donor on a monthly basis (2 TE vs 0.6, respectively). Therefore this technology has great potential to improve the genetic progress of buffalo through the maternal lineage.

Storage of buffalo (Bubalus bubalis) semen

Characteristics of buffalo semen, diluents used for liquid storage, aspects involved in freezing and thawing of semen are reviewed, and fertility results after artificial insemination (AI) with frozen-thawed semen are given.