Effect of Maca aqueous extract addition to a freezing extender for canine semen

This study investigated the effect of the addition of Lepidium meyenii (Maca) to the freezing extender on the post-thaw quality of dog semen. Ten canine ejaculates were frozen following a two-step protocol using a tris-glucose-citrate egg yolk extender with or without the addition of 10 µl/mL of aqueous extract of Maca (Maca and ctrl groups, respectively). Prior to (fresh semen) and after freezing (T0) sperm motility, kinetic parameters, viability and mitochondrial membrane potential (MMP), as well as the levels of malondialdehyde (MDA) were evaluated. In addition, sperm motility, kinetic parameters, viability and MMP were examined up to 2 h of incubation of 37 °C after thawing (T1 and T2) to evaluate thermo-resistance. The addition of Maca reduced MDA concentration at T0 (p < 0.05) and increased total motility, the percentage of sperm with medium velocity and WOB at T1. Progressive motility decreased (p < 0.05) at T1 in the ctrl group, whereas it was not affected in Maca group at any time point. In addition, the percentage of hyperactivated spermatozoa remained constant at T1 in the ctrl, while in the Maca group an increase (p < 0.05) of this parameter was recorded. Although no differences were found for MMP between groups at any time points, a decrease of viable sperm with low MMP was observed in ctrl group between T0 and T1 and in Maca group between T1 and T2. The addition of Maca prior freezing reduced the extent of lipid peroxidation and activated canine sperm motility and hyperactivation after thawing.

Dietary supplementation with green tea extract improves the antioxidant status and oocyte developmental competence in Italian Mediterranean buffaloes

The aim of this work was to assess the antioxidant status and the developmental competence of oocytes recovered by ovum pick-up (OPU) in Italian Mediterranean buffaloes supplemented with green tea extracts (GTE) for 90 days. Buffalo cows (n = 16) were randomly assigned to a control group receiving no supplement and a treatment group, receiving GTE starting 90 days before OPU, carried out for five consecutive sessions. Blood samples were collected before the start of supplementation with GTE (T0) and at day 45 (T1) and day 90 (T2) of supplementation, to measure ferric reducing activity (FRAP), total antioxidant capacity (TAC), superoxide dismutase (SOD) and catalase (CAT). The antioxidant status of follicles was measured as TAC on the follicular fluid collected from the dominant follicle just prior OPU, coinciding with T2, and at the end of five repeated OPU sessions (T3). Another objective was to assess in vitro the protective effects of green tea extracts on hepatic cells exposed to methanol insult. Different concentrations of GTE (0.5 μM and 1 μM) were tested on cultured hepatic cells and viability, morphology and SOD activity were assessed at 24, 48 and 72 h. Supplementation with GTE increased (P < 0.05) the number of total follicles (8.7 ± 0.5 vs 6.9 ± 0.5), the number and the percentage of Grade A + B cumulus-oocyte complexes (COCs) compared with the control (3.7 ± 0.4 vs 2.3 ± 0.3 and 57.5 ± 4.2 vs 40.4 ± 4.9 %, respectively). Oocyte developmental competence was improved in the GTE group as indicated by the higher (P < 0.05) percentages of Grade 1,2 blastocysts (44.8 vs 29.1 %). In the GTE group, plasma TAC was higher both at T1 and T2, while FRAP increased only at T2, with no differences in SOD and CAT. The TAC of follicular fluid was higher (P < 0.05) in the GTE compared to the control both at T2 and at T3 The in vitro experiment showed that co-treatment with methanol and 1 μM GTE increased (p < 0.01) cell viability at 24 h (P < 0.01), 48 h (P < 0.05) and 72 h (P < 0.01) compared with the methanol treatment co-treatment with 1 μM GTE prevented the decrease in SOD activity observed with methanol at 24 and 48 h of culture. In conclusion, the results of in vivo and in vitro experiments suggest that supplementation with GTE increases buffalo oocyte developmental competence, by improving oxidative status and liver function.

Effect of crocin supplementation in the extender on the quality of chilled canine semen

The aim of the study was to evaluate the effects of crocin on canine sperm quality parameters during prolonged storage at 4 °C. Ejaculates from 10 dogs were diluted in a TRIS- egg yolk extender supplemented with 0 (control group), 0.5, 1, and 2 mM crocin and stored at 4 °C. Sperm membrane functional integrity, motility, and kinetics were assessed after 3 h, 24 h, 4 days and 7 days of storage. Based on the results, the more efficient concentration of crocin (0.5 mM) was chosen to evaluate sperm intracellular ROS levels, lipid peroxidation, and DNA fragmentation vs. the control. Semen with the addition of 0.5 mM crocin with respect to the control exhibited: i) increased (P < 0.05) sperm membrane functionality at 4 and 7 days of storage; ii) higher (P < 0.05) average path (VAP), straight-line velocities (VSL), and beat cross frequency (BCF) at 4 d of storage at 4 °C; iii) decreased (P < 0.05) intracellular ROS levels after 3 and 24 h storage. No differences in lipid peroxidation and DNA fragmentation were recorded between the control and C0.5 groups at any time point. Lipid peroxidation did not increase over time, while DNA fragmentation increased (P < 0.05) in both groups after 4 days of storage. The results demonstrated that the enrichment of extender with crocin improves to a certain extent canine semen quality, particularly after 4 days of storage at 4 °C.

Review: Development, adoption, and impact of assisted reproduction in domestic buffaloes

The domestic buffalo (Bubalus bubalis), also known as water buffalo, comprises two sub-species the River buffalo (B. bubalis ssp. bubalis; 50 chromosomes) and the Swamp buffalo (ssp. carabanensis; 48 chromosomes). Domestic buffaloes are a globally significant livestock species. In South Asia, the River buffalo is a primary source of milk and meat and has a very important role in food security. The River buffalo also supports high-value, differentiated food production in Europe and the Americas. The Swamp buffalo is an important draft animal and a source of food in Southeast Asia and East Asia. The growing importance of buffaloes requires that they undergo an accelerated rate of genetic gain for efficiency of production, product quality, and sustainability. This will involve the increased use of assisted reproduction. The initial application of reproductive technology in buffaloes had variable success as it relied on the adoption of procedures developed for cattle. This included artificial insemination (AI), sperm cryopreservation, and embryo technologies such as cloning and in vitro embryo production (IVEP). Reproductive technology has been progressively refined in buffaloes, and today, the success of AI and IVEP is comparable to cattle. Ovarian follicular superstimulation (superovulation) combined with in vivo embryo production results in low embryo recovery in buffaloes and has limited practical application. The contribution of elite female buffaloes to future genetic improvement will therefore rely mainly on oocyte pickup and IVEP. This will include IVEP from females before puberty to reduce generation intervals. This review provides for the first time a clear chronology on the development, adoption, and impact, of assisted reproduction in domestic buffaloes.

Seasonal variations in the metabolomic profile of the ovarian follicle components in Italian Mediterranean Buffaloes

The aim of this work was to evaluate the seasonal effect on the metabolomic profile of the ovarian follicle in Italian Mediterranean buffalo to unravel the causes of the reduced competence during the non-breeding season (NBS). Samples of follicular fluid, follicular cells, cumulus cells and oocytes were collected from abattoir-derived ovaries during breeding season (BS) and NBS and analyzed by 1H Nuclear Magnetic Resonance. The Orthogonal Projections to Latent Structures of the Discriminant Analysis showed clear separation into seasonal classes and Variable Importance in Projection method identified differentially abundant metabolites between seasons. Seasonal differences were recorded in metabolite content in all analyzed components suggesting that the decreased oocyte competence during NBS may be linked to alteration of several metabolic pathways. The pathway enrichment analysis revealed that differences in the metabolites between the seasons were linked to glutathione, energy generating and amino acid metabolism and phospholipid biosynthesis. The current work allows the identification of potential positive competence markers in the follicular fluid as glutathione, glutamate, lactate and choline, and negative markers like leucine, isoleucine and β-hydroxybutyrate. These results form a major basis to develop potential strategies to optimize the follicular environment and the IVM medium to improve the competence of oocytes during the NBS.

Extracellular vesicles from seminal plasma to improve fertilizing capacity of bulls

Seminal plasma contains extracellular vesicles (EVs) that vehicle RNA, proteins, and other molecules able to influence the biological function of sperm. The aim of this study was to improve the fertilizing capacity of male gametes of low-fertility bulls using EVs isolated by ultracentrifugation from the seminal plasma of a bull of proven fertility. After dose-response curve, 10×106 sperm of low-fertility bulls were co-incubated for an hour with 400×106 EVs/ml. In addition, it has been verified that the incorporation of EVs, which takes place in the sperm midpiece, is maintained for 5 hours and even after cryopreservation. Subsequently, the spermatozoa of low-fertility bulls, with EVs incorporated, were used for the in vitro production of embryos. The rate of blastocyst at seventh day yield in vitro, with the use of sperm with EVs incorporated, increased by about twice the yield obtained with the same sperm in the absence of EVs: bulls having an average embryonic yield of 6.41±1.48%, 10.32±4.34% and 10.92±0.95% improved their yield to 21.21±1.99%, 22.17±6.09% and 19.99±5.78%, respectively (P<0.05). These encouraging results suggest that it might be possible to keep breeding bulls with poor fertility. Further studies will be needed to evaluate the in vivo fertility of sperm treated with EVs and understand how the content of EVs is involve in the sperm-vesicle interaction and in the improved sperm performance.

Variations of follicular fluid extracellular vesicles miRNAs content in relation to development stage and season in buffalo

In buffalo (Bubalus bubalis) reproductive seasonality, causing cycles of milk production, is one of the major factors affecting farming profitability. Follicular fluid (FF) contains extracellular vesicles (EVs) playing an important role in modulating oocyte developmental competence and carrying microRNAs (miRNAs) essential for in vitro fertilization outcomes. The aim of this work was to characterize the FF-EVs-miRNA cargo of antral (An) and preovulatory (pO) follicles collected in the breeding (BS) and non-breeding (NBS) seasons, to unravel the molecular causes of the reduced oocyte competence recorded in buffalo during the NBS. In total, 1335 miRNAs (538 known Bos taurus miRNAs, 324 homologous to known miRNAs from other species and 473 new candidate miRNAs) were found. We identified 413 differentially expressed miRNAs (DE-miRNAs) (FDR < 0.05) between An and pO groups. A subset of the most significant DE-miRNAs between An and pO groups targets genes which function is related to the lipid and steroid metabolism, response to glucocorticoid and oestradiol stimulus. Comparison between BS and NBS showed 14 and 12 DE-miRNAs in An-FF-EVs and pO-FF-EVs, which regulate IL6 release and cellular adhesion, respectively. In conclusion, these results demonstrated that the miRNA cargo of buffalo FF-EVs varies in relation to both follicular development and season.

An Integrative Genomic Prediction Approach for Predicting Buffalo Milk Traits by Incorporating Related Cattle QTLs

Background: The 90K Axiom Buffalo SNP Array is expected to improve and speed up various genomic analyses for the buffalo (Bubalus bubalis). Genomic prediction is an effective approach in animal breeding to improve selection and reduce costs. As buffalo genome research is lagging behind that of the cow and production records are also limited, genomic prediction performance will be relatively poor. To improve the genomic prediction in buffalo, we introduced a new approach (pGBLUP) for genomic prediction of six buffalo milk traits by incorporating QTL information from the cattle milk traits in order to help improve the prediction performance for buffalo. Results: In simulations, the pGBLUP could outperform BayesR and the GBLUP if the prior biological information (i.e., the known causal loci) was appropriate; otherwise, it performed slightly worse than BayesR and equal to or better than the GBLUP. In real data, the heritability of the buffalo genomic region corresponding to the cattle milk trait QTLs was enriched (fold of enrichment > 1) in four buffalo milk traits (FY270, MY270, PY270, and PM) when the EBV was used as the response variable. The DEBV as the response variable yielded more reliable genomic predictions than the traditional EBV, as has been shown by previous research. The performance of the three approaches (GBLUP, BayesR, and pGBLUP) did not vary greatly in this study, probably due to the limited sample size, incomplete prior biological information, and less artificial selection in buffalo. Conclusions: To our knowledge, this study is the first to apply genomic prediction to buffalo by incorporating prior biological information. The genomic prediction of buffalo traits can be further improved with a larger sample size, higher-density SNP chips, and more precise prior biological information.

The addition of crocin in the freezing medium extender improves post-thaw semen quality

Semen cryopreservation is arguably the most important method or technique contributing to the advancement of modern animal production. However, the quality of sperm after thawing is still highly variable. The addition of antioxidant compounds to the freezing medium has been used customarily to counteract the harmful effects of Reactive Oxygen Species (ROS) that are produced during the freeze/thaw process. Crocin, a potent antioxidant, improves the fertilizing capacity of spermatozoa. In this study, we evaluated the potential of crocin (0, 0.5 and 1 mM) as an extender additive to diminish the damaging effects of cryopreservation on bovine spermatozoa. Post-thaw semen quality was assessed by means of motility, viability and lipid peroxidation (LPO). We further investigated the effect of crocin supplementation upon freezing on sperm quality parameters during their incubation at 37°C for up to 2 hr. Overall, the data assessment indicates that crocin facilitated a general improvement of the quality of freeze/thawed spermatozoa, under the present experimental conditions. Crocin (1 mM) maintained a higher percentage of alive spermatozoa with intact acrosome with rapid and progressive motility, compared to the control extender. Moreover, the spermatozoa cryopreserved in the presence of crocin exhibited higher values in CASA kinematic parameters (VCL, VSL, VAP, ALH) immediately after thawing. Furthermore, the positive effect of crocin on motility parameters was also sustained over a period of 2 hr incubation at 37°C. This effect of crocin may be attributed to the observed inhibition of LPO during the incubation period. Thus, the results indicate that the addition of crocin (especially at a final concentration of 1 mM) in the freezing extender medium may benefit the preservation of the quality parameters of spermatozoa that are compromised by the freeze/thaw heat shock and the stress during handling for IVF or artificial insemination.

Effects of Dietary Supplementation of Conjugated Linoleic Acids and Their Inclusion in Semen Extenders on Bovine Sperm Quality

Simple Summary

Suboptimal fertility in males accounts for about two-thirds of infertility cases, thus being of serious concern for the dairy industry, where optimal fertility is fundamental for farm profitability. Although genetic defects responsible for subfertility have been identified, the role of seminal compounds on fertility remain unclear. Feeding rumen-protected isomers of conjugated linoleic acid (CLA) to dairy cows reportedly enhances circulating insulin-like growth factor I (IGF-I) levels. In breeding bulls, the IGF-I concentration in seminal plasma has been positively correlated with fertility rates. Therefore, the objective of the study was to evaluate the effect of dietary CLA supplementation and of their inclusion to the semen extender on bovine semen quality and freezability.

Abstract

Isomers of conjugated linoleic acid (CLA) enhances circulating insulin-like growth factor I (IGF-I) levels. Furthermore, fertility rate of breeding bulls is positively correlated to seminal plasma IGF-I concentration. Our objective was to evaluate the effect of dietary CLA supplementation and inclusion to the semen extender on bovine semen quality and freezability. Fourteen bulls, randomly assigned to control (CTL) and CLA (50 g/day) groups, were supplemented for 10 weeks. Samples were collected at Weeks −2 (before supplementation), 0, 4, 6 (during supplementation), 10, and 11 (after supplementation). Blood and seminal plasma were analyzed for IGF-I; the ejaculates were frozen in the following subgroups: CTL (no addition to semen extender), CLA c9, t11 (50 µM), CLA c9, t11 (100 µM), CLA t10, c12 (50 µM), CLA t10, c12 (100 µM), and CLA mix (50 µM each of CLA c9, t11 and CLA t10, c12). Sperm motility, morphology, viability, mitochondrial membrane potential, and reactive oxidative species were assessed. CLA supplementation decreased ejaculates’ total volume, increased sperm concentration, beat cross frequency, and decreased oxidative stress; it also increased plasma and seminal plasma IGF-I levels compared to the CTL. The inclusion of CLA c9, t11 100 µM and CLA mixture in the extender increased live spermatozoa percentage post-thawing compared to other groups. Our results show a beneficial effect of CLA supplementation on semen quality; however, further studies evaluating fertilization rates are necessary to corroborate the results.

80 Energetic substrate availability affects the metabolome profile in bovine sperm

Bovine spermatozoa are specialised cells that require high ATP production for flagellar movement and other physiological events necessary for fertilization. Glycolysis and oxidative phosphorylation (OXPHOS) are the most studied energy pathways in sperm cells and involve metabolites such as glucose, pyruvate, and lactate. Although glycolysis has been described as the preferential pathway for ATP generation in bovine spermatozoa, other metabolites may also be used, leading to distinct metabolome profiles. Thus, the objective of this work was to characterise the metabolome profile of culture media derived from sperm cells incubated in the presence of different energy substrates for ATP production. For that, a semen straw from one bull (n=3) previously tested for IVF was thawed and motile sperm were separated by Percoll gradient, washed and resuspended in FertTalp medium (FT) without capacitator agents (Parrish et al. 1989 Biol. Reprod. 41, 683–699) to a final concentration of 30×106cells mL−1. Then, samples were centrifuged and resuspended in 5 different groups: positive control (PC, FT supplemented with 2mM glucose, 0.2mM pyruvate, and 11mM lactate); negative control (NC, FT without energy substrates); Glu (FT and 3.5mM glucose); Pyr (FT and 0.11mM pyruvate), and Lac (FT and 5.5mM lactate). Samples were incubated at 38.5°C, 5% CO2 in high humidity for 15 and 45min. After incubation, samples were centrifuged and supernatant was collected and analysed by Raman spectroscopy as previously described (Santos et al. 2015 Biomed. Opt. Express 6, 2830–2839; https://doi.org/10.1364/BOE.6.002830). Data were preprocessed and submitted to principal component (PCA) and loading plot analysis (LP) by using Minitab software (Minitab Ltd.). The results showed that after 15min of incubation, the metabolic profiles were similar for the PC, Glu, and Lac groups, suggesting that they present similar metabolic activity. NC and Pyr were a separate cluster, indicating that pyruvate is not metabolized through OXPHOS in this phase. LP analysis comparing Glu and Pyr groups indicated phosphatidylserine, phenylalanine, DNA/RNA, and lipids as the most distinct metabolites. After 45min, PC and Pyr had a similar metabolome profile, whereas NC, Glu, and Lac clustered together, suggesting that for long-period incubation OXPHOS takes place as the preferential pathway for energy production in bovine sperm cells. At this time, the comparison of Glu versus Pyr revealed phosphatidylserine, proline, phenylalanine, carboxylic acid, DNA/RNA, proteins, and lipids as the most different metabolites between groups. Based on these results, we hypothesised that the glycolysis to OXPHOS transition may be a consequence of the depletion of glycolytic enzymes, leading the sperm cells to use distinct pathways for long-term maintenance of ATP production. In conclusion, our data showed that the metabolome profile of bovine spermatozoa varies according to the period of incubation and substrates availability for energy production. However, more studies are necessary to characterise the ability of these metabolites to maintain sperm motility and viability. This research was funded by FAPESP 2017/18384-0.

"Which Factors Affect Pregnancy Until Calving and Pregnancy Loss in Buffalo Recipients of in vitro Produced Embryos?"

In vitro embryo production and embryo transfer (ET) in buffaloes has been developed for decades. However, most studies are focused on the donor or laboratory improvements, and there is a lack of reports regarding the recipients. Therefore, our aim was to investigate factors associated to pregnancy (P/ET), pregnancy loss (PL), and calving rates in buffalo recipients. The studied factors were season, recipient parity, the synchronization protocol, the CL diameter, asynchrony between the embryo and the recipient, the day of the recipient estrous cycle, the embryo (fresh vs. vitrified), the day of embryo development, and the embryo stage. These retrospective data, from a program of in vitro produced embryos, were analyzed by logistic regression, and the odds ratio was also estimated. Two factors were related to P/ET and the calving rate: (1) progesterone associated to estradiol plus eCG protocol for fixed time ET tended to affect positively P/ET on day 30 (41.9 vs. 36.1%, respectively; P = 0.07; AOR = 1.28) and P/ET on day 60 (37.8 vs. 36.1%, respectively; P = 0.09; AOR = 1.08) compared to the Ovsynch protocol; and (2) the CL diameter (≥14.5 mm) at transfer increased P/ET on day 30 (47.4 vs. 32.5%; P < 0.01; AOR = 1.87) and on day 60 (45.3 vs. 27.7%; P < 0.01; AOR = 2.16), and also the calving rate (37.9 vs. 21.7%; P < 0.01; AOR = 2.20). PL was greater when ET was done in the nonbreeding season compared to the breeding season (PL 30-60: 12.8 vs. 0.0%, P = 0.01; AOR > 999.99; PL 60-calving: 26.8 vs. 3.6%, P = 0.03; AOR = 9.90; and PL 30-calving: 36.2 vs. 3.6%, P = 0.01; AOR = 15.30). In conclusion, the data of our study indicated that the synchronization protocol, the CL diameter, and ET during the breeding season impacted the reproductive efficiency of buffalo recipients.

FSH Stimulation with Short Withdrawal Improves Oocyte Competence in Italian Mediterranean Buffalo (Bubalus bubalis)

The aim of this work was to evaluate the efficiency of different FSH doses and FSH coasting times before ovum pick-up (OPU) on follicular growth and oocyte competence in buffalo. Experiment 1 involved two different FSH treatments: 40 mg FSH given three (FSH3) or six (FSH6) times, 2 days after dominant follicle removal were tested, with OPU carried out after 40-44 h of coasting. In experiment 2, OPU was carried out after FSH6 protocol followed by 28-32 h (C1), 40-44 h (C2), or 64-68 h (C3) of coasting time. Cumulus oocyte complexes (COCs) were classified, in vitro matured, fertilized, and cultured. The results demonstrated that FSH6 increased the total number of follicles, the number and percentages of medium and large follicles, the number and the proportion of good quality oocytes, and the number of grade 1,2 and fast-developing blastocysts compared to the control. C3 decreased the percentage of good quality oocyte and blastocyst rates compared to C1 and C2. A higher percentage of fast blastocysts and average number of grade 1,2 blastocysts was observed in C1 compared to C3, with intermediate values found in C2. The improved efficiency in terms of blastocyst yields suggests the use of FSH6 + C1 protocol for ovarian superstimulation in buffalo.

Evaluation of bovine sperm telomere length and association with semen quality

The study aimed to evaluate if the sperm telomere length can be considered as a new biomarker for sperm quality in bulls. Sperm Telomere Length was evaluated by Monochrome Multiplex Quantitative PCR in group A (n = 8) and group B (n = 8) bulls, classified according to standard semen analysis. Also, this parameter was measured before and after Percoll gradient separation within bulls that produced semen of satisfactory quality. Sperm telomere length, measured as T/S ratio (average ratio of telomere repeats copy number to a single copy gene), was higher in group A than in group B bulls (0.77 ± 0.03 vs 0.43 ± 0.06; P < 0.01). Sperm telomere length was positively correlated with motility, viability and membrane integrity, and it was negatively correlated with sperm anomalies. Furthermore, Percoll gradient selected sperms with higher T/S ratio than unselected sperms (1.19 ± 0.02 vs 0.67 ± 0.03). These results suggest that sperm telomere length can be used as a new marker of bovine semen quality.

Corpus Luteum Color Doppler Ultrasound and Pregnancy Outcome in Buffalo during the Transitional Period

Simple Summary

The advent of color Doppler ultrasonography promoted tremendous advances in research and clinical practice in animal reproduction, because it allowed noninvasive visualization of the vascularization in reproductive organs. In particular, the corpus luteum blood flow reflects luteal function better than luteal size in ruminants. Since buffaloes are a seasonal species, it is important to evaluate corpus luteum functionality also during the nonbreeding season, through blood flow examination and early pregnancy diagnosis. For this reason, we selected 29 Mediterranean buffaloes that had undergone synchronization and artificial insemination and were examined daily, from 5 to 10 days post-artificial insemination. Then, we retrospectively classified the buffaloes as pregnant or nonpregnant. Statistical analysis showed that pregnant animals had higher mean progesterone concentration and higher mean time average medium velocity values from Day 5 to Day 10 compared to nonpregnant buffaloes. Moreover, these two parameters could be used to predict the likelihood of pregnancy, starting on Day 6, although more reliable results could be obtained at Day 10 post-artificial insemination. In conclusion, a proper CL growth and development from Day 5 to Day 10 post-timed artificial insemination (TAI) is crucial for pregnancy maintenance during the transitional period.

Abstract

This study evaluated corpus luteum (CL) development in buffaloes out of breeding season and assessed an early pregnancy diagnosis. Mediterranean buffaloes (n = 29) were synchronized and artificially inseminated. CL B-mode/color Doppler ultrasonography examinations were performed daily from Days 5 to 10 post-synchronization, recording CL dimensions and blood flow parameters. Blood samples were collected on the same days for the progesterone (P₄) assay. Data were grouped into pregnant or nonpregnant and retrospectively analyzed. The total pregnancy rate was 50.0% (13/26) on Day 45. A significant difference between CL average area in pregnant and nonpregnant buffaloes was recorded only on Day 10. Pregnant buffaloes showed a significantly higher mean P₄ concentration and higher mean time average medium velocity (TAMV) values from Day 5 to Day 10 compared to nonpregnant buffaloes. Linear regression analysis showed a significant relationship between P₄ levels and TAMV. Multiple logistic regression highlighted a significant influence of TAMV on pregnancy outcome, particularly on Day 8. This is probably due to the strong relationship between TAMV and P₄ production. Both TAMV and P₄ could be used to predict pregnancy starting on Day 6, although a more reliable result was obtained at Day 10. Thus, the period between Days 5 and 10 is critical for CL development during the transitional period in buffalo.

Changes in Bull Semen Metabolome in Relation to Cryopreservation and Fertility

Semen cryopreservation determines several sperm damages, including the loss of fertility-associated proteins. The purpose of the study was to compare the metabolite contents in bovine sperm and seminal plasma before and after cryopreservation, and between high- and low-fertility bulls in vitro. Forty-eight ejaculates, collected from eight bulls (six per bull), were analyzed by liquid chromatography-mass spectrometry. Cryopreservation resulted in an over-expression of lysophosphatidylcholine (0:0/18:2(9Z,12Z)) in seminal plasma. In addition, higher levels of glycine betaine and pyro-l-glutaminyl-l-glutamine were observed in cryopreserved compared to fresh spermatozoa. The fresh seminal plasma of high-fertility bulls showed an over-expression of l-acetylcarnitine, glycerol tripropanoate, 2,3-diacetoxypropyl stearate and glycerophosphocholine, and an under-expression of lysophosphatidylcholine and butyrylcarnitine, compared to low-fertility bulls. Higher levels of glycerophosphocholine and lysophosphatidylcholine (16:0/0:0) were recorded in fresh spermatozoa from high-fertility bulls. In high-fertility bulls, a greater content of glycerophosphocholine and lower levels of butyrylcarnitine, glycine betaine and l-carnitine were found in cryopreserved seminal plasma, and lower levels of glycine betaine were detected in cryopreserved spermatozoa. In conclusion, cryopreservation affects bovine semen metabolome at both plasmatic and cellular compartments, and metabolic profile differs between high- and low-fertility bulls.

Effect of caspase inhibitor Z-VAD-FMK on bovine sperm cryotolerance

The aim of this study was to evaluate the treatment of bovine semen with the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK), before or after freezing on semen quality. After the initial assessment, sperm from 4 bulls were pooled (Experiment 1) and cryopreserved in BioXcell containing 0, 20 and 100 μM Z-VAD-FMK. After thawing semen viability, motility, membrane integrity, as well as DNA fragmentation and ΔΨm were evaluated. In Experiment 2, bovine frozen/thawed sperm were incubated for 1 hr with 0, 20 and 100 µM Z-VAD-FMK before assessing the semen quality. The treatment with Z -VAD-FMK before cryopreservation improved post-thawing sperm motility compared to the control group (p < .05), while no differences were recorded in sperm viability and membrane integrity among groups (on average 86.8 ± 1.5 and 69.1 ± 1.4, respectively). Interestingly, at the highest concentration, DNA fragmentation decreased (p < .05), while the percentage of spermatozoa with high ΔΨm increased (p < .05). The results of Experiment 2 showed that 1-hr treatment with Z-VAD-FMK did not affect sperm motility and viability (on average 63.4 ± 5.8 and 83.7.1 ± 1.2, respectively). However, Z-VAD-FMK improved sperm membrane integrity (p < .05) and at the highest concentration tested decreased the proportion of sperm showing DNA fragmentation (p < .05). No differences were recorded in the percentage of spermatozoa with high ΔΨm (on average 57.0 ± 11.4). In conclusion, the treatment with 100 µM of the caspase inhibitor Z-VAD-FMK before freezing increased bovine sperm mass motility and ΔΨm, while decreasing sperm DNA fragmentation. Treatment of semen after thawing with 100 µM Z-VAD-FMK improved sperm membrane integrity and reduced DNA fragmentation.

142 Metabolomic analysis of fresh and frozen bovine seminal plasma: A preliminary study

Sperm cryopreservation is essential for assisted reproduction; however, freezing induces biochemical and physical damage to the sperm membrane structures, negatively affecting sperm fertilising ability (Castro et al. 2006 J. Anim. Sci. Biotechnol. 5, 1-9). Metabolomics is the study of small molecules, commonly known as metabolites, which play essential roles in biological systems. Emerging research in the field of metabolomics showed a potential role in identifying male fertility biomarkers (Bieniek et al. 2016 Asian J. Androl. 18, 426-433). Metabolites present in the seminal plasma play several roles related to sperm motility, sperm membrane protection from oxidative stress, and regulation of metabolic activity (Therien et al. 1995 Biol. Reprod. 52, 1372-1379). However, the extent of metabolite changes in seminal plasma during cryopreservation is still not well known. Therefore, the aim of this study was to evaluate the differences of the seminal plasma metabolites between fresh and frozen bovine sperm. Four ejaculates from eight Holstein (Bos taurus) bulls (4-6 years age) maintained at an authorised national semen collection center (Centro Tori Chiacchierini, Civitella D’Arna, Italy) under uniform management conditions were collected weekly using an artificial vagina (IMV Technologies). Each ejaculate was split into two aliquots (one fresh and one frozen) at −20°C for at least 2h. Seminal plasma from fresh (immediately) and frozen-thawed semen was separated from sperm by centrifugation (1600×g for 10min), and supernatants were then transferred to a 2-mL tube and stored at −80°C until use. After methanol extraction of metabolites, samples were centrifuged at 6400×g for 30min at 4°C, and supernatants were analysed using a liquid chromatography-mass spectrometry (LC-MS; Agilent 1260 HPLC; Agilent Technologies) system with an autosampler and a binary pump coupled to an Agilent Q-TOF 6540 (Agilent Technologies). Univariate analyses of the data were performed using bioinformatics approaches. The differences between fresh and frozen seminal plasma samples were analysed using a paired Student's t-test. Twenty-three metabolites were found in both fresh and frozen seminal plasma samples, out of which eight were significantly different (P&lt;0.05) between the two groups; among these, hypotaurine, ceramide, and isoindoline were identified. In particular, hypotaurine and ceramide were downregulated, whereas isoindoline was upregulated in fresh samples compared with frozen samples. To the best of our knowledge, this is the first study to identify seminal plasma metabolites in fresh and frozen samples by using LC-MS. In order to ensure the reliability and accuracy of results, the validation of the method used in the analysis of biosamples is still in progress, as is the evaluation of the metabolic profile in sperm cells. In conclusion, the results of this study suggest that LC-MS can be a promising screening tool to detect metabolites potentially associated with bull fertility.

148 Bull spermatozoa uptake of extracellular vesicles from bovine seminal plasma

Extracellular vesicles (EV) are important mediators of intercellular communication because they transfer microRNA (miRNA) that are able to repress translation of mRNA. Their presence in seminal plasma suggests a role in sperm fertility. It is known that bull seminal plasma contains fertility-associated proteins that are predictive of high and low fertility (Killian et al. 1993 Biol. Reprod. 49, 1202-1207). In addition, a difference in miRNA content between high and low spermatozoa motility has been observed in bulls, highlighting a potential role of EV on fertility (Capra et al. 2017 BMC Genom. 18, 14). We hypothesised that co-incubation of sperm of low-fertility bulls with EV isolated from the seminal plasma of high-fertility bulls could improve their fertility. Before testing this hypothesis, a preliminary study was carried out to investigate the presence and type of EV in bovine seminal plasma and their interaction with spermatozoa. Ejaculates of eight Holstein bulls collected weekly by artificial vagina were centrifuged at 1600×g for 10min to pellet spermatozoa and then centrifuged again at 2400×g for 30min to eliminate cell debris and large vesicles. After centrifugation, supernatants were collected and filtered twice (0.45 and 0.22µm) and stored at −80°C. A double ultracentrifugation at 100 000×g for 1h was performed, and pellets resuspended in a small volume of Tris buffer were kept at −80°C until used. Three ejaculates of the same bull were pooled to detect the concentration and size of EV by Nanosight Instruments. To trace the interaction with spermatozoa by fluorescence microscopy, EV were labeled with PKH26 dye and a dose-response curve in three replicates was performed. A suspension of 1×106 spermmL−1 was co-incubated with 200 or 400×106 EV labelled with pKH26 for 30, 60, 90, 120, 150, and 180min at 38.5°C. The end point of incubation was at 24h. Internalisation of EV was assessed using confocal microscopy. Our results showed that the size of EV ranged from 145.1 to 187.7nm, with an average of 166±29nm. For all seminal plasma samples, the number of EV ranged from 3.62 to 6.08×1013 particlesmL−1, with an average of 4.37±0.61×1013. Based on size, these EV can be categorised as shedding vesicles. Confocal microscopy was set to take fluorescent images at different planes scanned every 0.12µm from top to bottom of the spermatozoa. Our results showed that no fluorescence signal was detectable after co-incubation with 200×106 EV. At the concentration of 400×106 EV, up to 60min no signal was detectable, whereas at 90min spermatozoa showed a fine granular fluorescent pattern within the intermediate portion. At 120min, the signal was within the acrosome, and at 180min the spermatozoa were stained for the whole length, supposing a distribution of incorporated EV throughout all the cell. At 24h, the fluorescence signal decreased. In conclusion, this is the first study to demonstrate that bull spermatozoa incorporate EV from bull semen. We hypothesise that a transfer of molecules, such as miRNA and other noncoding RNA molecules, from EV to spermatozoa is probably involved in sperm fertility.

Integrative Analysis of Transcriptome and GWAS Data to Identify the Hub Genes Associated With Milk Yield Trait in Buffalo

The mammary gland is the production organ in mammals that is of great importance for milk production and quality. However, characterization of the buffalo mammary gland transcriptome and identification of the valuable candidate genes that affect milk production is limited. Here, we performed the differential expressed genes (DEGs) analysis of mammary gland tissue on day 7, 50, 140, and 280 after calving and conducted gene-based genome-wide association studies (GWAS) of milk yield in 935 Mediterranean buffaloes. We then employed weighted gene co-expression network analysis (WGCNA) to identify specific modules and hub genes related to milk yield based on gene expression profiles and GWAS data. The results of the DEGs analysis showed that a total of 1,420 DEGs were detected across different lactation points. In the gene-based analysis, 976 genes were found to have genome-wide association (P ≤ 0.05) that could be defined as the nominally significant GWAS geneset (NSGG), 9 of which were suggestively associated with milk yield (P < 10⁻⁴). Using the WGCNA analysis, 544 and 225 genes associated with milk yield in the turquoise module were identified from DEGs and NSGG datasets, respectively. Several genes (including BNIPL, TUBA1C, C2CD4B, DCP1B, MAP3K5, PDCD11, SRGAP1, GDPD5, BARX2, SCARA3, CTU2, and RPL27A) were identified and considered as the hub genes because they were involved in multiple pathways related to milk production. Our findings provide an insight into the dynamic characterization of the buffalo mammary gland transcriptome, and these potential candidate genes may be valuable for future functional characterization of the buffalo mammary gland.

Genome-Wide SNP Data Revealed the Extent of Linkage Disequilibrium, Persistence of Phase and Effective Population Size in Purebred and Crossbred Buffalo Populations

Linkage disequilibrium (LD) is a useful parameter for guiding the accuracy and power of both genome-wide association studies (GWAS) and genomic selection (GS) among different livestock species. The present study evaluated the extent of LD, persistence of phase and effective population size (Ne) for the purebred (Mediterranean buffalo; n = 411) and crossbred [Mediterranean × Jianghan × Nili-Ravi buffalo, n = 9; Murrah × Nili-Ravi × local (Xilin or Fuzhong) buffalo, n = 36] buffalo populations using the 90K Buffalo SNP genotyping array. The results showed that the average square of correlation coefficient (r ²) between adjacent SNP was 0.13 ± 0.19 across all autosomes for purebred and 0.09 ± 0.13 for crossbred, and the most rapid decline in LD was observed over the first 200 kb. Estimated r ² ≥ 0.2 extended up to ~50 kb in crossbred and 170 kb in purebred populations, while average r ² values ≥0.3 were respectively observed in the ~10 and 60 kb in the crossbred and purebred populations. The largest phase correlation (R _{P, C} = 0.47) was observed at the distance of 100 kb, suggesting that this phase was not actively preserved between the two populations. Estimated Ne for the purebred and crossbred population at the current generation was 387 and 113 individuals, respectively. These findings may provide useful information to guide the GS and GWAS in buffaloes.

28 Effect of deuterium oxide on bovine oocyte cryotolerance

It is known that cryopreservation triggers spindle disassembly, increased aneuploidy risk, decreased post-thaw survival, fertilization, and embryo development. We hypothesised that a treatment with D2O before vitrification would slow down oocyte metabolism and reduce ice crystal formation by replacing water inside the cells. The aim of the study was to evaluate the effect of a 4-h treatment with different D2O concentrations (0, 3, 15, and 30%) on cryotolerance of bovine in vitro-matured oocytes. Abattoir-derived bovine oocytes were matured in vitro for 20h in TCM-199 medium with 15% of bovine serum (BS), 0.5µg mL−1 of FSH, 5µg mL−1 of LH, 0.8mM l-glutamine, and 50µg mL−1 of gentamicin at 39°C with 5% of CO2 and randomly divided into 5 experimental groups. A group of non-vitrified oocytes was used as the fresh oocyte control group, whereas the remaining oocytes were incubated for 4h in in vitro maturation medium with 0% (vitrified control; n=205), 3% (n=205), 15% (n=205), and 30% D2O (n=205) before vitrification. The experiment was repeated 4 times. Oocytes were denuded in HEPES-buffered TCM-199 (H199)+5% BS and vitrified using a cryotop freezing straw. The oocytes were incubated in 200μL of H199+20% BS with 7.5% ethylene glycol and 7.5% dimethyl sulfoxide for 3min. After that, oocytes were collected in 50μL of H199+20% fetal bovine serum with 15% ethylene glycol+15% dimethyl sulfoxide and 0.5M sucrose for 20s and plunged into LN2. One month later, oocytes were warmed in thawing media with decreasing concentrations of sucrose (1.35M to 0.31M) and then placed into in vitro maturation medium for 2h before IVF. Matured oocytes were IVF and cultured according to standard procedures (Rubessa et al. 2011 Theriogenology 76, 1347-1355). Cleavage and blastocyst rates were evaluated after 7 days of culture. Data were analysed using the GLM procedure of SPSS (SPSS Inc., Chicago, IL, USA). The least statistical difference post-hoc test was used to perform statistical multiple comparison. The α-level was set at 0.05. As expected, both cleavage [60.5±4.6 (fresh control); 36.9±2.6 (0% D2O); 46.3±3.7 (3% D2O); 31.6±2.4 (15% D2O); and 24.4±2.6 (30% D2O)] and blastocyst rates [25.7±0.8 (fresh control); 9.0±0.8 (0% D2O); 9.0±0.7 (3% D2O); 3.6±0.2 (15% D2O); and 4.3±0.8 (30% D2O)] decreased in all vitrified groups compared with the fresh control group. Within vitrified oocytes, cleavage rate increased (P&lt;0.05) with 3% D2O treatment compared with the other groups. However, pretreatment with higher (15-30%) D2O concentrations decreased (P&lt;0.05) blastocyst rates of vitrified-warmed oocytes. In conclusion, a pretreatment with low concentrations (3%) of D2O improved the cleavage rate of bovine vitrified-warmed oocytes, suggesting a potential beneficial effect, whereas deleterious effects were observed using the higher concentrations. Therefore, further studies are required to assess a potential use of D2O to improve oocyte cryotolerance, likely testing different incubation times.

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.

26 Season affects cryotolerance of in vitro-produced buffalo embryos

Buffaloes are tendentially short-day breeders, and seasonality is one of the main factors affecting the feasibility of ovum pickup and in vitro embryo production technology in this species. An improvement of oocyte developmental competence during decreasing daylight months was previously reported in Italian Mediterranean buffalo (Di Francesco et al. 2011 Anim. Reprod. Sci. 123, 48-53). The aim of this work was to evaluate whether season also affects embryo quality and cryotolerance. Abattoir-derived buffalo cumulus-oocyte complexes were collected during the breeding season, characterised by decreasing daylight length (n=349 over 6 replicates), and the non-breeding season, characterised by increasing daylight length (n=770 over 12 replicates). Buffalo cumulus-oocyte complexes were in vitro matured, fertilized, and cultured according to standard procedures (Di Francesco et al. 2011 Anim. Reprod. Sci. 123, 48-53). The embryos obtained by the end of culture (i.e. on Day 7 post-IVF) were scored for quality and developmental stage, and the percentages of total transferable embryos (tight morulae and blastocysts) were recorded. Embryos (n=107 and 110 in the breeding and non-breeding seasons, respectively) were vitrified by cryotop in 16.5% ethylene glycol, 16.5% dimethyl sulfoxide, and 0.5M sucrose (Boccia et al. 2013 Ital. J. Anim. Sci. 12, 492-496). Warming was carried out by plunging the cryotop strip into a 0.25M sucrose solution and transferring the embryos into 0.15M sucrose for 5min. Embryos were then washed and cultured in SOF for 24h to evaluate post-culture viability. The resistance to cryopreservation was evaluated by assessing the survival rate, on the basis of morphological criteria, and development rate (i.e. the percentage of embryos that resumed their development and reached a more advanced developmental stage) after 24h post-warming culture. Data were analysed by Student’s t-test. Both cleavage (82.8±4.3v. 73.1±1.7 in the breeding and non-breeding seasons, respectively; P&lt;0.05) and blastocyst (32.9±3.5v. 18.3±1.7 in the breeding and non-breeding seasons, respectively; P&lt;0.01) rates increased during the breeding season, confirming previous observations. Due to the different efficiency, a higher number of replicates was required during the non-breeding season to obtain an equal number of embryos. In addition, a seasonal effect was recorded on embryo quality, indicated by poorer cryotolerance of in vitro-produced buffalo embryos during the non-breeding season. Indeed, both survival (94.6±2.7% and 74.0±5.5% in the breeding and non-breeding seasons, respectively; P&lt;0.01) and development (67.3±7.6% and 40.0±7.2% in the breeding and non-breeding seasons, respectively; P&lt;0.01) rates of vitrified blastocysts decreased after 24h post-warming culture in the non-breeding season. These findings suggest that the reduced developmental competence of buffalo oocytes during the non-breeding season may also lead to lower blastocyst quality. This is in contrast to the evidence in cattle that embryo quality is mainly determined by culture conditions, whereas blastocyst production depends on oocyte quality.

161 Dichloroacetate influences the mitochondrial activity of bovine oocytes impairing meiotic progression

Pyruvate is a key energy substrate for the oocyte during maturation and acquisition of developmental competence. Mitochondrial activity is also essential for oocyte competence. Dichloroacetate (DCA) is an inhibitor of pyruvate dehydrogenase kinase that indirectly stimulates pyruvate dehydrogenase (PDH), increasing pyruvate oxidation. PDH converts pyruvate into acetyl coenzyme A (acetyl-CoA) and thereby modulates the entry of glucose-derived carbons into the tricarboxylic acid (TCA) cycle, the main ATP production pathway within the oocyte. It was reported that DCA addition to embryo culture media improves embryo development in aged mice, by enhancing mitochondrial membrane potential (MMP) and decreasing oxidative stress (McPherson et al. 2014 Fertil. Steril. 101, 1458-1466). We hypothesised that increased pyruvate metabolism through the oxidative pathway, by stimulating PDH activity with DCA, could influence in vitro oocyte maturation. The aim of this work was to evaluate the effect of different concentrations of DCA during in vitro maturation (IVM) of bovine oocytes on maturation rate and mitochondrial activity, by assessing MMP and levels of flavin adenine dinucleotide (FADH2), nicotinamide adenine dinucleotide hydride (NADH), and reactive oxygen species (ROS). Abattoir-derived bovine cumulus-oocytes complexes (COC; n=360, over 4 replicates) were in vitro-matured with 0 (Control; n=120), 0.5mM (n=120) and 5mM (n=120) of DCA. After maturation, all matured COC were denuded by mechanical pipetting and meiotic progression was assessed by Hoechst 33342 staining and MMP by MitoTracker Red CMXRos test (Thermo Fisher Scientific, Waltham, MA, USA). Moreover, FADH2 and NADH levels were evaluated by autofluorescence (Dumollard et al. Development 134, 455-465) and ROS levels by CellRox® Green test (Thermo Fisher Scientific). Data were analysed by ANOVA, and the Tukey post hoc test was used to evaluate the difference among groups. The α-level was set at 0.05. Treatment with both concentrations of DCA decreased maturation rate (86.1, 67.8, and 67.6% in 0, 0.5, and 5mM groups, respectively; P&lt;0.05). The MMP increased in oocytes matured with the highest concentration of DCA (3.42±0.28, 4.44±0.51, and 6.32±0.89 pixel/mm2, with 0, 0.5, and 5mM DCA, respectively; P&lt;0.05). In line with this, higher levels of FADH2 (3.16±0.15, 3.96±0.24, and 3.83±0.20 pixel/mm2, with 0, 0.5, and 5mM DCA, respectively; P&lt;0.05) and NADH (3.86±0.14, 4.80±0.16, and 4.95±0.17 pixel/mm2, with 0, 0.5, and 5mM DCA, respectively; P&lt;0.05) were found in both DCA-treated groups compared with the control. Unexpectedly, ROS levels increased in the presence of DCA (0.9±0.07, 1.30±0.12, and 1.54±0.16 pixel/mm2, with 0, 0.5, and 5mM DCA, respectively; P&lt;0.05) compared with the control. These results suggest that DCA was effective in stimulating mitochondrial activity of bovine oocytes, but also resulting in increased oxidative stress that likely accounts for the decreased maturation rate. Therefore, alternative strategies should be identified for the manipulation of the oocyte metabolic profile to improve oocyte developmental competence.

27 Effects of the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone on frozen - thawed bovine sperm

Semen cryopreservation is critical for appropriate planning of both AI and IVF trials, improving the benefit:cost ratio. However, cryopreservation induces damage in mammalian spermatozoa, resulting in decreased fertility (Medeiros et al. 2002 Theriogenology 57, 327-344). It is known that cryopreservation and thawing induce apoptosis in a variety of cells, including bovine sperm (Anzar et al. 2002 Biol. Reprod. 66, 354-360). Cryotolerance of in vitro-produced bovine embryos was recently improved by inhibiting apoptosis using a caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (ZVAD-FMK), during vitrification and subsequent culture (Pero et al. 2018 Theriogenology 108, 127-135). The aim of this work was to evaluate whether treatment of bovine frozen-thawed sperm with the caspase inhibitor Z-VAD-FMK may prevent aberrant apoptosis and consequently improve sperm viability. Six ejaculates from 12 bulls were used for the trial. Semen was diluted at 37°C with BioXcell extender (BioXcell, West Lebanon, NH) to a final concentration of 30×106 spermatozoa mL−1, and straws were kept at 4°C for 4h and then frozen in an automated system. After thawing, Percoll-separated spermatozoa were incubated at 37°C for 1h with 0, 20, and 100µM ZVAD-FMK. Sperm viability and membrane integrity were assessed by Trypan Blue/Giemsa and hypo-osmotic swelling test, respectively, as previously described (Longobardi et al. 2017 Theriogenology 88, 1-8). Sperm motility was examined by phase contrast microscopy at 40× magnification on a thermoregulated stage at 37°C. Apoptosis was evaluated by TUNEL technique, which assesses DNA fragmentation (Takeda et al. 201561, 185-190). The mitochondrial membrane potential was then assessed by flow cytometric analysis with the mitochondrial probe JC-1 (Garner and Thomas 1999Mol. Reprod. Dev. 53, 222-229). Data were analysed by ANOVA using least significant difference as post-hoc test. The treatment of bovine frozen-thawed sperm with 100µM ZVAD-FMK decreased the percentage of sperm exhibiting DNA fragmentation (17.8±1.1, 13.3±2.8, and 10.5±2.5 with 0, 20, and 100µM ZVAD, respectively; P&lt;0.05). Moreover, both concentrations of ZVAD-FMK increased the percentage of hypo-osmotic swelling test+ sperm, indicating improved membrane integrity compared with the control (60.5±3.5, 70.9±2.1, and 74.3±2.1 with 0, 20, and 100µM ZVAD-FMK, respectively; P&lt;0.01). However, no differences were found in sperm viability (82.3±0.5, 84.6±1.0, and 84.3±2.1 with 0, 20, and 100µM ZVAD-FMK, respectively) and motility (60.0±2.9, 62.5±3.4, and 67.5±2.1 with 0, 20, and 100µM ZVAD-FMK, respectively). Furthermore, no differences were observed among groups in the percentage of sperm exhibiting normal mitochondrial membrane potential (62.4±12.7, 57.9±12.8, and 50.8±8.8 with 0, 20, and 100µM ZVAD, respectively). In conclusion, caspase inhibition with 100µM ZVAD-FMK after thawing was effective in reducing sperm DNA fragmentation and increasing sperm membrane integrity, suggesting a beneficial effect on fertility. However, as the other fertility-related parameters did not improve, further investigations are required to draw definite conclusions.

Novel insights into the genetic basis of buffalo reproductive performance

Background

Fertility is a complex trait that has a major impact on the development of the buffalo industry. Genome-wide association study (GWAS) has increased the ability to detect genes influencing complex traits, and many important genes related to reproductive traits have been identified in ruminants. However, reproductive traits are influenced by many factors. The development of the follicle is one of the most important internal processes affecting fertility. Genes found by GWAS to be associated with follicular development may directly affect fertility. The present study combined GWAS and RNA-seq of follicular granulosa cells to identify important genes which may affect fertility in the buffalo.

Results

The 90 K Affymetrix Axiom Buffalo SNP Array was used to identify the SNPs, genomic regions, and genes that were associated with reproductive traits. A total of 40 suggestive loci (related to 28 genes) were identified to be associated with six reproductive traits (first, second and third calving age, calving interval, the number of services per conception and open days). Interestingly, the mRNA expressions of 25 of these genes were also observed in buffalo follicular granulosa cells. The IGFBP7 gene showed high level of expression during whole antral follicle growth. The knockdown of IGFBP7 in buffalo granulosa cells promoted cell apoptosis and hindered cell proliferation, and increased the production of progesterone and estradiol. Furthermore, a notable signal was detected at 2.3–2.7 Mb on the equivalent of bovine chromosome 5 associated with age at second calving, calving interval, and open days.

Conclusions

The genes associated with buffalo reproductive traits in this study may have effect on fertility by regulating of follicular growth. These results may have important implications for improving buffalo breeding programs through application of genomic information.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5208-6) contains supplementary material, which is available to authorized users.

160 Exposure to Cadmium Affects Oocyte and Embryo Competence in Cattle

There is a growing worldwide concern regarding the increased release of the heavy metal cadmium (Cd) in the environment, due to several industrial processes, as it is known to affect health. Among other heavy metals, Cd is widely recognised to influence the reproductive system at different levels, interfering with both gametes and embryo functions in several species (Thompson and Bannigan, 2008 Reprod. Toxicol. 25, 304-315). The in vitro model can be used to mimic environmental conditions allowing us to evaluate their effect on oocyte maturation and early embryo development. Therefore, the aim of this study was to evaluate the influence of different Cd concentrations on nuclear maturation, apoptosis in cumulus cells, and cleavage and blastocyst yields in cattle. For this purpose, abattoir-derived bovine oocytes were in vitro matured, fertilized, and cultured according to standard procedures (Rubessa et al. 2011 Theriogenology 76, 1347-1355). In particular, oocytes were matured with 0 (control; n = 126), 0.1 μM (n = 139), 1 μM (n = 134), and 10 μM of Cd (n = 135), at 39°C under humidified air with 5% CO2, 7% O2, and 88% N2. For each replicate, after 22 h of maturation, a representative sample of oocytes (n = 10 per each group) was used to evaluate nuclear maturation by 4′,6-diamidino-2-phenylindole (DAPI) staining and another sample (n = 10 per each group) to assess cumulus-cells complex apoptosis by TUNEL/Hoechst staining (Pocar et al. 2005 Reproduction 130, 857-868). The remaining oocytes were in vitro fertilized and cultured with 0 (n = 106), 0.1 μM (n = 119), 1 μM (n = 114), and 10 μM (n = 115) Cd. The experiment was repeated 3 times. On Day 8 post-IVF, the blastocyst yields were recorded. Differences among groups were analysed by ANOVA, with the least significant difference method used as a post hoc test. Data are presented as means ± SE. Unexpectedly, the exposure of oocytes to Cd during IVM did not affect the percentage of oocytes undergoing nuclear maturation (on average 96.3 ± 2.3). In contrast, concentrations of 1 and 10 μM Cd increased the percentage of apoptotic cumulus-cells in cumulus–oocyte complexes (COC) compared with the control (3.4 ± 0.4, 10.6 ± 1.8, 15.0 ± 0.9, 16.7 ± 4.0, respectively, with 0, 0.1, 1, and 10 μM; P < 0.05). It is worth pointing out that with the highest concentration, cumulus expansion did not occur and cumulus cells appeared detached from the oocyte. Likewise, 1 and 10 μM Cd decreased cleavage rates compared with the control (68.7 ± 1.8, 54.3 ± 5.0, 58.5 ± 4.2 and 2.8 ± 2.6, respectively, with 0, 0.1, 1, and 10 μM Cd; P < 0.01). Finally, blastocyst yields decreased when oocytes were treated with 0.1 μM Cd and no development to blastocyst was observed at the 2 higher concentrations (35.1 ± 1.7, 26.2 ± 3.1, 0, 0, respectively, with 0, 0.1, 1, and 10 μM; P < 0.01). In conclusion, exposure to Cd during maturation negatively affects bovine COC, as indicated by the increased apoptotic index in cumulus cells, without influencing the nuclear maturation process. Furthermore, the presence of Cd during in vitro fertilization and culture severely impairs both the fertilization and post-fertilization embryo development.

123 In Vitro Embryo Production in Lyophilized In Vitro Culture Medium as a Method to Increase the Medium's Shelf-Life

The worldwide production of livestock embryos requires stable medium with long shelf life. In this experiment, we evaluated the impact of the freeze-dried in vitro culture (IVC) medium (Mdry) on in vitro embryo production. We compared the standard IVC and Mdry media for cleavage rate and embryo production. Media solutions (10 mL) were aliquoted into 50-mL conical tubes and lyophilized to form a powder concentrate using a Genesis freeze-dryer (VirTis, Gardener, NY, USA). Lyophilization consisted of a constant cooling from 20°C to –10°C at a constant rate of 1°C/min with a 2-h hold at –10°C before sublimation at 0°C. Mdry medium were held at –80°C for 4 months. When the IVC medium was rehydrated, the pH were adjusted to 7.4. Abattoir-derived Holstein oocytes (n = 618, in 7 replicates) were in vitro matured and fertilized with sexed semen, according to standard procedures (Rubessa et al. 2011 Theriogenology 76, 1347-1355). Twenty hours after IVF, presumptive zygotes were cultured in SOF medium with 5% BS at 39°C with 5% CO2, 7% O2, and 88% N2. On Day 7, embryo yields were assessed. All recorded parameters were subjected to a Chi-Square Test 2 × 2. The parameters compared were percent cleavage, blastocysts, and embryos/cleaved. The α level was set at 0.05. All data were expressed as quadratic means and mean standard errors. The results (Table 1) showed not a statistical difference between control and Mdry. The Mdry had a higher percentage of cleaved zygotes (65.4% v. 53.4%) but not enough for a statistical difference. However, when we compared embryo production, there was no difference between treatments. The ratio between blastocysts and cleaved embryos was higher in the control group but not significant according to our selected α level. These results indicate that it is possible lyophilize IVC medium without interfering with the potential quality of the medium. Further studies will be needed to better understand the positive effect of the lyophilization on the cleavage rate. Table 1.Mean (SD in parentheses) percentage cleavage and blastocysts

Genome-wide association studies to identify quantitative trait loci affecting milk production traits in water buffalo

Water buffalo is the second largest resource of milk supply around the world, and it is well known for its distinctive milk quality in terms of fat, protein, lactose, vitamin, and mineral contents. Understanding the genetic architecture of milk production traits is important for future improvement by the buffalo breeding industry. The advance of genome-wide association studies (GWAS) provides an opportunity to identify potential genetic variants affecting important economical traits. In the present study, GWAS was performed for 489 buffaloes with 1,424 lactation records using the 90K Affymetrix Buffalo SNP Array (Affymetrix/Thermo Fisher Scientific, Santa Clara, CA). Collectively, 4 candidate single nucleotide polymorphisms (SNP) in 2 genomic regions were found to associate with buffalo milk production traits. One region affecting milk fat and protein percentage was located on the equivalent of Bos taurus autosome (BTA)3, spanning 43.3 to 43.8 Mb, which harbored the most likely candidate genes MFSD14A, SLC35A3, and PALMD. The other region on the equivalent of BTA14 at 66.5 to 67.0 Mb contained candidate genes RGS22 and VPS13B and influenced buffalo total milk yield, fat yield, and protein yield. Interestingly, both of the regions were reported to have quantitative trait loci affecting milk performance in dairy cattle. Furthermore, we suggest that buffaloes with the C allele at AX-85148558 and AX-85073877 loci and the G allele at AX-85106096 locus can be selected to improve milk fat yield in this buffalo-breeding program. Meanwhile, the G allele at AX-85063131 locus can be used as the favorable allele for improving milk protein percentage. Genomic prediction showed that the reliability of genomic estimated breeding values (GEBV) of 6 milk production traits ranged from 0.06 to 0.22, and the correlation between estimated breeding values and GEBV ranged from 0.23 to 0.35. These findings provide useful information to understand the genetic basis of buffalo milk properties and may play a role in accelerating buffalo breeding programs using genomic approaches.

Cholesterol-loaded cyclodextrins prevent cryocapacitation damages in buffalo (Bubalus bubalis) cryopreserved sperm

The aim of this study was to investigate the effect of cholesterol-loaded cyclodextrins (CLC) on motility, viability, capacitation status, and in vivo fertility of buffalo frozen-thawed sperm. After the initial semen assessment, buffalo sperm were diluted in BULLXcell extender containing 0- (control), 1.5-, and 3-mg/mL CLC and cryopreserved. At thawing, sperm motility was evaluated by phase contrast microscopy, and viability-capacitation status was assessed by Hoechst 33258-chlortetracycline (CTC) assay. Capacitation status was also evaluated by an indirect immunofluorescence assay to localize phosphotyrosine-containing proteins. Moreover, buffaloes were artificial inseminated to assess the in vivo-fertilizing potential of CLC-treated semen. No differences among control, 1.5-, and 3-mg/mL CLC-treated groups were recorded in both sperm motility (66.5 ± 5.6, 68.8 ± 4.8, and 68.8 ± 4.8, respectively) and viability (86.5 ± 1.9, 87.6 ± 1.5, 88.4 ± 2.3, respectively). However, the extender supplementation with CLC significantly reduced sperm cryocapacitation. Indeed, CLC treatment decreased (P < 0.01) the proportion of sperm showing the CTC pattern B (capacitated sperm) compared with the control (69.6 ± 3.4, 37.8 ± 1.5, and 51.3 ± 4.7, respectively, with 0, 1.5-, and 3-mg/mL CLC; P < 0.01). Furthermore, the percentage of sperm displaying tyrosine-phosphorylated pattern EA (i.e. high capacitation level) was reduced (P < 0.01) in both CLC-treated groups (10.8 ± 3.3 and 5.6 ± 1.6, respectively, with 1.5- and 3-mg/mL CLC) compared with the control (37.3 ± 6.9), reaching values similar to those recorded in fresh semen (11.0 ± 3.5). In addition, treating sperm with 3-mg/mL CLC increased (P < 0.01) the percentage of nonfluorescent (pattern NF), i.e., non-capacitated sperm (41.8 ± 3.6) compared with fresh semen (11.0 ± 6.9). No differences were recorded in pregnancy rates at 60 days post-artificial insemination among control, 1.5- and 3-mg/mL CLC groups (59.7%, 65.6%, and 56.9%, respectively). In conclusion, CLC treatment of buffalo sperm strongly decreases sperm cryocapacitation damages, without affecting the in vivo fertilizing capability.

164 CARNITINE IMPROVES POST-THAWING SPERM MOTILITY BY INCREASING ADENOSINE TRIPHOSPHATE CONTENT IN BUFFALO (Bubalus bubalis)

Semen cryopreservation plays a critical role for a wide application of both AI and in vitro embryo production in buffalo. In this species, spermatozoa are more susceptible to hazards during freezing and thawing than cattle spermatozoa, thus resulting in lower fertilizing potential (Andrabi et al. 2008 Anim. Reprod. Sci. 104, 427–433). Carnitine is a quaternary ammonium compound with antioxidant capacities, able to reduce the availability of lipids for peroxidation by transporting fatty acids into the mitochondria for β-oxidation to generate adenosine triphosphate (ATP) energy (Tanphaichitr and Leelahagul 1993 Nutrition 9, 246–54). It is known that cryopreservation processes decreases the intracellular concentration of carnitine in spermatozoa (Reyes-Moreno et al. 2000 J. Androl. 21, 876–86). In cattle, supplementation of semen extender with carnitine improves sperm motility and DNA integrity (Bucak et al. 2010 Cryobiology 61, 248–53). The aim of this study was to evaluate whether supplementation of semen extender with carnitine would increase ATP content in buffalo sperm and affect post-thawing motility. Eight ejaculates from 4 bulls were used for the trial. Each ejaculate was split into 3 equal aliquots and diluted at 37°C with BioXcell extender containing 0 (control), 2.5, and 7.5 mM carnitine to a final concentration of 30 × 106 spermatozoa/mL. After 4 h at 4°C, the straws were frozen in an automated system. At thawing, sperm motility was evaluated by phase contrast microscopy at 40× magnification (Gillan et al. 2008 Anim. Reprod. Sci. 103, 201–204). Adenosine triphosphate content was measured using a Colourimetric ATP Assay Kit (Biovision, Milpitas, CA, USA). Briefly, Percoll-separated spermatozoa were homogenised and then deproteinized using 10-kDa spin columns. Samples were incubated at RT for 30 min and absorbance was measured at 570 nM in a microplate reader. Differences in sperm motility and ATP content among groups were analysed by ANOVA. Both concentrations of carnitine increased post-thawing sperm motility compared with the control (44.4 ± 3.5, 53.1 ± 3.9, and 52.5 ± 3.6, respectively, with 0, 2.5, and 7.5 mM carnitine; P < 0.05). Interestingly, carnitine increased ATP content of buffalo frozen–thawed sperm in a dose-dependent manner (4.1 ± 0.1, 5.3 ± 0.1, and 8.2 ± 0.4 nM × 108 sperm, respectively, with 0, 2.5, and 7.5 mM carnitine; P < 0.01). In conclusion, the enrichment of semen extender with carnitine improved post-thawing motility of buffalo sperm by boosting mitochondrial ATP production, hence providing energy for use by spermatozoa.

51 CASPASE-3 INHIBITOR Z-VAD-FMK ENHANCES CRYOTOLERANCE OF IN VITRO-PRODUCED BOVINE PRE-IMPLANTATION EMBRYOS

In vitro-produced (IVP) bovine embryos are still less viable and resistant to cryopreservation than their in vivo counterparts. Cryopreservation induces cell degeneration through the apoptotic pathway in bovine oocytes and embryos (Men et al. 2003 Cryobiology 47, 73–81). Apoptosis can be prevented by inhibition of caspase activity, leading to improved cryosurvival in mammalian cells (Stroh et al. 2002 FASEB J. 16, 1651–3). Interestingly, cryotolerance of porcine embryos was improved by inhibiting apoptosis using a caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK) during vitrification and subsequent culture (Men et al. 2006 Theriogenology 66, 2008–16). Aim of this work was to evaluate whether cryotolerance of bovine IVP embryos may be improved by using Z-VAD-FMK during cryopreservation and post-warming in vitro culture. Abattoir-derived bovine oocytes (n = 753, over 4 replicates) were in vitro matured and fertilized according to standard procedures (Rubessa et al. 2011 Theriogenology 76, 1347–55). Twenty hours after IVF, presumptive zygotes were cultured in SOF medium at 39°C with 5% CO2, 7% O2, and 88% N2. On Day 7, embryo yields were assessed and blastocysts (except the hatched blastocysts) were randomly divided in 2 groups: vitrification and post-warming culture in presence (n = 60) or absence (n = 54) of 20 µM Z-VAD-FMK. Vitrification was carried out by Cryotop in 16.5% ethylene glycol, 16.5% DMSO, and 0.5 M sucrose (Rubessa et al. 2011 Theriogenology 76, 1347–55). Blastocysts were warmed in decreasing sucrose solutions (0.25 M for 1 min and 0.15 M for 5 min) and cultured for 2 days. Resistance to cryopreservation was evaluated by assessing the survival rate, based on morphological criteria and hatching rate after 48 h culture. Furthermore, TUNEL staining was used to evaluate the total cell (TC) number and the apoptotic rate of vitrified blastocysts after 48-h post-warming culture. Differences between groups in survival and hatching rates after 48-h post-warming culture were analysed by Chi-squared test, whereas differences in TC number and in number and percentage of apoptotic cells were analysed by Student’s t-test. Inhibition of caspase activity induced by Z-VAD-FMK increased embryo cryotolerance, as indicated by higher survival (92.6 v. 55.0%; P < 0.01) and hatching rates (40.7 v. 23.3%; P < 0.05) after 48 h of post-warming culture. Furthermore, Z-VAD-FMK decreased both the average number (7.1 ± 0.6 v. 4.2 ± 0.3; P < 0.01) and the percentage (6.3 ± 0.6 v. 3.0 ± 0.2; P < 0.01) of apoptotic cells in blastocysts. No differences were recorded in TC number between groups (on average, 128.90 ± 1.6). These results suggest that addition of 20 µM Z-VAD-FMK during vitrification/warming and post-warming culture significantly inhibits apoptosis (DNA fragmentation) and improves the cryotolerance of IVP bovine embryos.

Crocetin improves the quality of in vitro-produced bovine embryos: Implications for blastocyst development, cryotolerance, and apoptosis

The aim of this work was to assess the effect of supplementation of bovine culture medium with the natural antioxidant crocetin on in vitro blastocyst development and quality. This was evaluated as cryotolerance, apoptosis index, and total cells number and allocation. Abattoir-derived oocytes were matured and fertilized in vitro according to standard procedure. Twenty hours after IVF, presumptive zygotes were cultured in synthetic oviduct fluid medium, supplemented with 0, 1, 2.5, and 5 μM crocetin (experiment 1) at 39 °C under humidified air with 5% CO2, 7% O2, and 88% N2. On Day 7, embryo yields were assessed and the blastocysts were vitrified by Cryotop method in 16.5% ethylene glycol, 16.5% DMSO, and 0.5 M sucrose. Finally, blastocysts produced on Day 8 in the absence (control) and presence of 1 μM crocetin were used for terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling and differential staining to evaluate, respectively, the apoptotic rate and the allocation of cells into inner cell mass (ICM) and trophectoderm (TE) lineages (experiment 2). Embryo development was higher in the 1 μM crocetin group compared to the control, both in terms of total embryo output (37.7 ± 4.2%, 52.9 ± 6.3%, 40.9 ± 7.6%, and 42.4 ± 8.7%, respectively, with 0, 1, 2.5, and 5 μM; P < 0.01) and grade 1 and 2 blastocysts (33.6 ± 4.9%, 46.1 ± 7.3%, 37.8 ± 7.9%, and 39.4 ± 7.9%, respectively, with 0, 1, 2.5, and 5 μM; P < 0.05). Moreover, the percentage of fast-developing embryos increased in 1 μM crocetin group compared to the control (23.4 ± 4.7%, 32.7 ± 6.6%, 27.2 ± 6.6%, and 30.1 ± 7.2%, respectively, with 0, 1, 2.5, and 5 μM; P < 0.05). In addition, the enrichment of culture medium with 1 μM crocetin improved embryo cryotolerance compared to the control, as indicated by higher hatching rates recorded after 48 hours postwarming culture (46.5% vs. 60.4%; P < 0.05). Furthermore, 1 μM crocetin decreased both the average number (9.9 ± 0.4 vs. 7.1 ± 0.3) and the percentage of apoptotic cells (7.1 ± 0.4 vs. 4.2 ± 0.2) in blastocysts compared to the control (P < 0.01). However, no differences were recorded in the average number of ICM, TE, and total cells between 1 μM crocetin and control groups. In conclusion, the enrichment of bovine culture medium with 1 μM crocetin increased both blastocyst yield and quality, as indicated by the improved chronology of embryo development, increased resistance to cryopreservation, and reduced incidence of apoptosis.

Effect of Relaxin on Fertility Parameters of Frozen-Thawed Buffalo (Bubalus bubalis) Sperm

The aim of this work was to evaluate the effect of relaxin on fertility parameters of buffalo frozen/thawed sperm. Sperm were incubated in the absence of capacitating agents (negative control), with a known capacitating agent such as heparin (positive control) and with 50 and 100 ng/ml relaxin for 2 and 4 h. Sperm viability, motility, capacitation and the effect of relaxin on the fertilizing ability after heterologous IVF were evaluated. Although viability was not affected, relaxin increased (p < 0.05) sperm motility compared to the negative and positive controls both after 2 h (60.0 ± 2.0, 60.0 ± 3.1, 68.3 ± 1.7 and 69.4 ± 2.7, respectively, in negative control, positive control, 50 and 100 ng/ml relaxin) and 4 h (55.0 ± 2.5, 53.3 ± 3.0, 62.2 ± 3.0 and 65.0 ± 3.2, respectively, in negative control, positive control, 50 and 100 ng/ml relaxin) incubation. When sperm were incubated with both 100 ng/ml relaxin and heparin, a decrease (p < 0.01) of pattern A, that is low capacitation level, was observed compared to the negative control both after 2 h (54.4, 34.3 and 36.4%, respectively, in negative control, positive control and 100 ng/ml relaxin) and 4 h (51.9, 35.0 and 34.3%, respectively, in negative control, positive control and 100 ng/ml relaxin). Moreover, an increase (p < 0.01) of pattern EA, that is high capacitation level, was recorded with 100 ng/ml relaxin and heparin compared to the negative control both after 2 h (44.1, 59.3 and 57.7%, respectively, in negative control, positive control and 100 ng/ml relaxin) and after 4 h (43.0, 54.4 and 56.0%, respectively, in negative control, positive control and 100 ng/ml relaxin). Finally, relaxin increased (p < 0.01) cleavage rate compared to the negative control (57.1 ± 4.4, 72.5 ± 6.0, 71.4 ± 5.5 and 73.6 ± 2.9, respectively, in negative control, positive control, 50 and 100 ng/ml relaxin). In conclusion, relaxin has a beneficial effect on motility, capacitation and fertilizing ability of frozen-thawed buffalo sperm.

Anti-Mullerian hormone (AMH) concentration in follicular fluid and mRNA expression of AMH receptor type II and LH receptor in granulosa cells as predictive markers of good buffalo (Bubalus bubalis) donors

High individual variability in follicular recruitment and hence in the number of embryos produced is a major factor limiting the application of reproductive technologies in buffalo. Therefore, the identification of reliable markers to select embryo donors is critical to enroll buffaloes in embryo production programs. Better understanding of factors involved in follicular growth is also necessary to improve the response to superovulation in this species. The aim of this work was thus to determine the anti-Mullerian hormone (AMH) concentration in follicular fluid (FF) recovered from different size follicles and evaluate the mRNA expression profiles of development-related (AMHR2, CYP19A1, FSHR, and LHR) and apoptosis-related genes (TP53INP1 and CASP3) in the corresponding granulosa cells (GCs) in buffalo. Another objective was to evaluate whether the AMH concentration in FF and gene expression of GCs is associated with the antral follicular count. Ovaries were collected at the slaughterhouse, and all follicles were counted and classified as small (3-5 mm), medium (5-8 mm), and large (>8 mm). Follicular fluid was recovered for AMH determination, and the mRNA expression of AMHR2, FSHR, LHR, CYP19A1, TP53INP1, and CASP3 was analyzed in GCs. The AMH concentration in FF decreased (P < 0.01) at increasing follicular diameter. The mRNA expression of AMHR2 and FSHR was higher (P < 0.05) in small follicles, whereas that of LHR and CYP19A1 was higher (P < 0.05) in large follicles. The intrafollicular AMH concentration was positively correlated with the antral follicular count (r = 0.31; P < 0.05). Interestingly, good donors (≥12 follicles) had a higher (P < 0.05) concentration of AMH and AMHR2 levels in small follicles and higher (P < 0.05) LHR levels in large follicles than bad donors (<12 follicles). These results suggest a potential use of AMH to select buffalo donors to enroll in embryo production programs, laying the basis for further investigations.