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.

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 ß-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.

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.

Effect of Aqueous Extract of Maca Addition to an Extender for Chilled Canine Semen.

Antioxidant supplementation has been proposed as a new strategy to improve the long-term preservation of semen. The aim of this study was to evaluate the effect of Maca supplementation of semen extender on quality-related canine semen parameters during cooling. Ejaculates from nine dogs were cooled for 7 days in the absence (control group) or in the presence of 10, 20 and 50 µL/mL of an aqueous extract of Maca. Sperm were evaluated for sperm viability, motility, DNA fragmentation and lipid peroxidation after 3 h, 24 h, 4 days and 7 days of storage. The addition of 10 µL/mL of Maca preserved sperm DNA and plasma membrane integrity at 3 h and increased sperm curvilinear velocity after 24 h. Treatment with 20 and 50 µL/mL of Maca increased the percentage of hyperactivated sperm after 3 h. Moreover, semen treated with 20 µL/mL of Maca decreased lipid peroxidation at 24 h. A significant reduction of sperm DNA and plasma membrane integrity as well as of kinetics parameters between 3 and 24 h of refrigerated storage with the higher concentration tested was observed. Although Maca was not able to protect canine semen with extended refrigeration storage time, it increased hyperactivation and preserved DNA integrity in short-term storage.

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

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.

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.

Seasonal effects on miRNA and transcriptomic profile of oocytes and follicular cells in buffalo (Bubalus bubalis).

Season clearly influences oocyte competence in buffalo (Bubalus bubalis); however, changes in the oocyte molecular status in relation to season are poorly understood. This study characterizes the microRNA (miRNA) and transcriptomic profiles of oocytes (OOs) and corresponding follicular cells (FCs) from buffalo ovaries collected in the breeding (BS) and non-breeding (NBS) seasons. In the BS, cleavage and blastocyst rates are significantly higher compared to NBS. Thirteen miRNAs and two mRNAs showed differential expression (DE) in FCs between BS and NBS. DE-miRNAs target gene analysis uncovered pathways associated with transforming growth factor ß (TGFß) and circadian clock photoperiod. Oocytes cluster in function of season for their miRNA content, showing 13 DE-miRNAs between BS and NBS. Between the two seasons, 22 differentially expressed genes were also observed. Gene Ontology (GO) analysis of miRNA target genes and differentially expressed genes (DEGs) in OOs highlights pathways related to triglyceride and sterol biosynthesis and storage. Co-expression analysis of miRNAs and mRNAs revealed a positive correlation between miR-296-3p and genes related to metabolism and hormone regulation. In conclusion, season significantly affects female fertility in buffalo and impacts on oocyte transcriptomic of genes related to folliculogenesis and acquisition of oocyte competence.

Crocin Improves the Quality of Cryopreserved Goat Semen in Different Breeds.

The effect of crocin in the semen extender before cryopreservation was evaluated on sperm parameters of 20 bucks of five different breeds: Garganica (GA), Jonica (JO), Maltese (MA), Mediterranean Red (MR) and Saanen (SA). Semen samples were centrifuged, to remove seminal plasma, divided in two aliquots and diluted with Tris-egg-yolk-based extender, containing 0 (control group) and 1 mM crocin. Crocin concentration was established after a preliminary dose trial. On fresh and frozen-thawed sperm, motility, viability, morphology, membrane integrity, DNA fragmentation and ROS levels were evaluated. The freezing process led to a decrease (p < 0.05) in all the sperm parameters recorded, confirming the deleterious effect of cryopreservation on goat semen. The most interesting result regarding the inclusion of crocin in the extender before cryopreservation was as follows: Crocin significantly improved (p < 0.05) sperm motility in all breeds, except for Mediterranean Red, compared to the control group. Furthermore, 1 mM crocin reduced percentage of spermatozoa with DNA fragmentation with a marked decrement (p < 0.05) in Garganica and Saanen, as compared to the control group. Finally, intracellular ROS decreased (p < 0.01) in the crocin-treated sperm of all breeds, as compared to the control. In conclusion, supplementation of 1 mM crocin in the extender decreased oxidative stress, improving sperm motility and the DNA integrity of frozen-thawed sperm in different breeds.

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.

Analysis of meiotic segregation by triple-color fish on both total and motile sperm fractions in a t(1p;18) river buffalo bull.

Chromosomal aberrations are relatively frequent pathologies in both humans and animals. Among them, translocations present a specific meiotic segregation pattern able to give a higher percentage of unbalanced gametes that can induce fertility problems. In this study, the meiotic segregation patterns of 1p, 1q and 18 Bubalus bubalis chromosomes were analyzed in both total sperm fraction and motile sperm fraction of a t(1p;18) carrier and a control bulls by triple-color FISH analysis with a pool of specific BAC probes. The frequencies of each total sperm fraction products in the carrier resulting from alternate, adjacent I, adjacent II and 3:1 segregation were 39%, 20%, 1% and 38%, respectively. On the other hand, the frequencies of each motile sperm fraction products in the carrier resulting from alternate, adjacent I, adjacent II and 3:1 segregation were 93%, 5%, 0% and 2%, respectively. The frequencies of normal sperms in the carrier were 27% and 69% in total sperm fraction and motile sperm fraction, respectively. The frequencies detected in motile sperm fraction were also validated by comparison with bull's progeny. To our knowledge, this is the first report on the meiotic segregation patterns in motile sperm fractions of B. bubalis bull carrying a chromosomal translocation. These data suggest that translocation has a very limited effect on aneuploidy in the gametes, and therefore, on the reproductive abilities of the bull.

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.

Carnitine supplementation decreases capacitation-like changes of frozen-thawed buffalo spermatozoa.

The aim of this study was to evaluate the effect of carnitine supplementation of semen extender on fertility parameters of frozen-thawed buffalo sperm. Buffalo semen was cryopreserved in BioXcell containing 0 (control group), 2.5 and 7.5-mM carnitine. After thawing, viability, motility, membrane integrity and capacitation status (assessed by localization of phosphotyrosine-containing proteins and chlortetracycline, chlortetracycline assay) were evaluated. Furthermore, total antioxidant capacity, reactive oxygen species (ROS) and lipid peroxidation levels, as well as adenosine triphosphate (ATP) content and phospholipids concentration were assessed. Finally, in vitro-fertilizing ability was evaluated after heterologous IVF. An increased post-thawing sperm motility and membrane integrity were recorded in both treated groups compared with the control (44.4 ± 3.5, 53.1 ± 3.9, and 52.5 ± 3.6%; P < 0.05 and 48.44 ± 0.69, 55.19 ± 0.54, 59.63 ± 0.30%; P < 0.01 with 0, 2.5-mM, and 7.5-mM carnitine, respectively). Supplementation of carnitine to the freezing extender decreased (P < 0.01) the percentage of sperm displaying fluorescence at both equatorial and anterior acrosomal regions (pattern EA), corresponding to high capacitation level, compared with the control (30.3 ± 3.8, 18.8 ± 2.8, and 7.2 ± 2.9%, respectively, with 0, 2.5-mM, and 7.5-mM carnitine). In agreement with this, carnitine also decreased (P < 0.01) the percentage of sperm displaying chlortetracycline pattern B (capacitated sperm) (63.8 ± 1.8, 46.8 ± 2.2, and 37.2 ± 1.8%, respectively with 0, 2.5-, and 7.5-mM carnitine). Interestingly, carnitine increased total antioxidant capacity and ATP content of buffalo frozen-thawed sperm (1.32 ± 0.02, 1.34 ± 0.01, 1.37 ± 0.01 mM/L and 4.1 ± 0.1, 5.3 ± 0.1 and 8.2 ± 0.4 nM × 108 sperm; P < 0.01, respectively, with 0, 2.5- and 7.5-mM carnitine). Intracellular ROS decreased in carnitine-treated sperm compared with the control, as indicated by dihydroethidium (DHE) values (0.22 ± 0.01, 0.18 ± 0.01, and 0.14 ± 0.0 µM/100 µL dihydroethidium, respectively, with 0, 2.5-, and 7.5-mM carnitine; P < 0.01), whereas lipid peroxidation levels (on average 30.5 ± 0.3 nmol/mL MDA) and phospholipids concentration (on average 0.14 ± 0.00 µg/120 × 106 sperm) were unaffected. Despite the improved sperm quality, the percentage of normospermic penetration after IVF was not influenced (on average 53.5 ± 1.8). In conclusion, enrichment of extender with carnitine improved buffalo sperm quality by increasing ATP generation and modulating ROS production, without affecting in vitro fertilizing ability.

Resveratrol prevents capacitation-like changes and improves in vitro fertilizing capability of buffalo frozen-thawed sperm.

The aim of this study was to evaluate the effect of resveratrol supplementation of semen extender on fertility parameters of frozen-thawed buffalo sperm. After the initial semen assessment, buffalo semen was cryopreserved in BioXcell containing 0 (control group), 0.5, 1, 10, and 50-µM resveratrol. After thawing, viability, motility, and capacitation status (assessed by localization of phosphotyrosine-containing proteins) were evaluated. Based on the results of the dose-response trial, the concentration of 50 µM was selected for further assessments, such as membrane integrity, total antioxidant capacity, reactive oxygen species, and lipid peroxidation (LPO) levels. Moreover, in vitro fertilizing ability by heterologous IVF and in vivo fertility were assessed. No differences among groups were recorded in sperm motility and viability (on average 52.3 ± 2.1% and 76.6 ± 1.3%, respectively). However, data showed a resveratrol dose-dependent effect on sperm capacitation status, with a significant reduction of the cryopreservation-induced capacitation with the higher concentrations tested. In particular, both 10- and 50-µM resveratrol increased (P < 0.01) the percentage of sperm displaying pattern A (low capacitation level), but treatment with 50-µM resveratrol also decreased (P < 0.01) the proportion of sperm exhibiting pattern EA (high-capacitation level) compared with the control. Interestingly, supplementation of semen extender with resveratrol increased membrane integrity, indicated by the higher percentage of hypo-osmotic swelling positive sperm (55.6 ± 0.6 vs. 48.4 ± 0.7; P < 0.01), and total antioxidant capacity (1.36 ± 0.01 vs. 1.32 ± 0.02 mM/L; P < 0.05) compared with the control. Intracellular reactive oxygen species decreased in resveratrol-treated sperm compared with the control, as indicated by dihydroethidium values (0.17 ± 0.01 and 0.22 ± 0.01 µM/µL dihydroethidium, respectively; P < 0.01). Moreover, when IVF was carried out by using semen treated with 50 µM resveratrol, the normal fertilization rate considerably improved (60.8%, P < 0.05) compared with the control (51.3%). However, no differences were recorded in pregnancy rates at 60 days post-AI with resveratrol-treated semen (50 µM) compared with the control (48.7 vs. 46.5%, respectively). In conclusion, the inclusion of 50-µM resveratrol in the extender decreases capacitation-like changes and oxidative stress, improving membrane stability and in vitro fertilizing ability of buffalo semen.

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.

Osteopontin improves sperm capacitation and in vitro fertilization efficiency in buffalo (Bubalus bubalis).

The aim of this study was to evaluate the effect of osteopontin (OPN), an ubiquitous acid glycoprotein, on in vitro sperm capacitation and on in vitro embryo production (IVEP) efficiency in buffalo. In experiment 1, after swim-up separation the sperm were incubated in Tyrode albumin lactate pyruvate medium in the absence of capacitating agents (control), with the standard concentration of heparin (0.01 mM) and three different concentrations of OPN (0.1, 1, and 10 mcg/mL), both in the presence and absence of heparin, for 2 and 4 hours. Capacitation was assessed indirectly by estimating the percentage of acrosome-reacted sperm after incubation with lysophosphatidylcholine. In order to determine the effect of OPN, in the presence of heparin, on fertilization (Experiment 2) and in vitro embryo development (experiment 3), in vitro-matured buffalo oocytes were fertilized in the presence of 0, 0.1, 1, and 10 mcg/mL of OPN. After IVF, the presumptive zygotes were dezonated, fixed, stained, and then evaluated microscopically. At Days 5 and 7 of culture, the cleavage and blastocyst rates were evaluated, respectively. Two hours of treatment with OPN at the two higher concentrations (1 and 10 mcg/mL) promoted in vitro capacitation of buffalo sperm (experiment 1). A synergic action of OPN with heparin was also done for all OPN concentrations tested. At 4 hours incubation, all treatments, including heparin (20.4%), improved (P < 0.01) capacitation compared with the control (16.2%). Interestingly, the best results were reported in all groups treated with OPN + heparin (40.8%, 38.6%, and 33.8%, respectively; P < 0.01). The addition of OPN to the IVF medium had a positive influence on total penetration, synchronous pronuclei formation (experiment 2), and IVEP efficiency (experiment 3). In particular, the two lower concentrations of OPN (0.1 and 1 mcg/mL), compared with the control, gave higher synchronous pronuclei formation (73.5%, 75.0%, and 46.5%, respectively; P < 0.01) and cleavage rates (70.3%, 71.6%, and 59.3%, respectively; P < 0.01). Interestingly, the treatments also improved blastocyst yields (29.3%, 30.3%, and 19.4%, respectively; P < 0.01). In conclusion, these results indicate that adding OPN to the IVF system improves IVEP efficiency by enhancing in vitro sperm capacitation and blastocyst yields in buffalo.

Effect of energy source during culture on in vitro embryo development, resistance to cryopreservation and sex ratio.

The aim of this work was to evaluate whether minimizing the glucose concentration during culture or replacing the hexose with other energy substrates and/or embryotrophic compounds would affect the in vitro development, the resistance to cryopreservation and the sex ratio of bovine embryos. In vitro matured and fertilized oocytes were randomly assigned to 4 groups for in vitro culture, that differed in the energy substrates included: group A) 1.5 mM glucose, as in standard SOF; group B) 0.15 mM glucose; group C) 0.125 mM G3P, in the presence of 0.15 mM glucose and group D) 0.34 mM citrate, in combination with 2.77 mM myo-inositol. Blastocysts were evaluated on day 7, then vitrified by cryotop in 16.5% DMSO, 16.5% EG and 0.5 M sucrose and warmed in decreasing concentration of sucrose (0.25 to 0.15 M sucrose). The survival rates were assessed after 24 h in vitro culture. Finally, the blastocysts produced were sexed by PCR. An increased blastocyst rate was recorded in groups B, C and D, i.e., when glucose concentration was reduced, compared to group A (28.2, 41.0, 35.7 and 35.8, respectively in groups A, B, C and D; P < 0.01). However, the embryos cultured in group D showed the slowest developmental speed, indicated by the lowest percentage of advanced stage-embryos (expanded and hatched blastocysts) out of the total blastocysts (56.1, 45.8, 56.9 and 31.8 %, respectively in groups A, B, C and D; P < 0.01). Furthermore, survival rates after 24 h culture of vitrified-warmed blastocysts also decreased in group D (73.3, 73.1, 71.4 and 58.4%, respectively in groups A, B, C and D; P < 0.01). Interestingly, in group D a higher percentage of female embryos was obtained compared to group A, with intermediate values in groups B and C (45.6, 53.4, 50.0 and 61.5%, respectively in groups A, B, C and D; P < 0.05). In conclusion, it was demonstrated that the energy substrate during in vitro culture affects both the production and the viability of blastocysts. Furthermore, manipulating the metabolic profile of embryos during in vitro culture may have an impact on sex ratio.