IGF-1 stabilizes goat sperm mitochondrial transmembrane potential and reduces dna fragmentation.

BACKGROUND: Antioxidant present in sperm cells protects them from oxidative damage. However, sperm are more susceptible to peroxidative damages due to the loss of these enzymes during cryopreservation and their survival and fertility may be compromised. Insulin like growth factor-1 (IGF-1) has an antioxidant effect and could maintain sperm motility. OBJECTIVE: To improve seminal parameters, mitochondrial membrane potential (MMP), oxidative status and DNA integrity of buck semen after freeze-thawing by fortification of goat semen diluent with various concentrations of IGF-1. MATERIALS AND METHODS: Fifty ejaculates were collected and were extended with tris- citric acid- fructose diluent with 10% egg yolk and 6% glycerol with sperm concentrations of 1×108 mL-1. Post-cryopreserved sperm were assessed for motility and a range of other functional parameters. RESULTS: In post-thaw semen sperm motility, live sperm count, acrosome integrity, hypo-osmotic swelling positive spermatozoa, malondialdehyde (MDA), protein carbonyl content (PCC), TUNEL positive sperm differed significantly (P<0.05) with the various concentrations of IGF-1 used. Sperm functional parameters post-thawing were significantly (P<0.05) better in 250 ng/mL IGF-1. IGF-1 protects against lipid peroxidation by lowering MDA and PCC production, thus reducing the harmful effect of reactive oxygen species. The kidding percentage using the artificial insemination technique was significantly higher ( i.e., 40%) in the group supplemented with 250 ng/mL of IGF-1 than in the non-supplemented group (i.e., 30%). CONCLUSION: IGF-1 may be used to improve post-thaw semen quality and fertility as measured by actual kidding rate. Doi.org/10.54680/fr23610110312.

Establishment of effective and safe recipient preparation for germ-cell transplantation with intra-testicular busulfan treatment in pre-pubertal Barbari goats.

The busulfan, an alkylating agent, suppresses endogenous spermatogenesis in recipient testes. However, considering a wide variation in the effects of busulfan among animal species, its dosage and route of infusion need optimization to prepare effective and safe recipients. Thus, the current study aimed to create a suitable recipient goat model for germ cell (Gc) transplantation through a single intra-testicular (i.t.) busulfan infusion under ultrasonographic (USG) guidance. As observed through the infusion of trypan blue under USG guidance into mediastinum testis (MT) of pre-pubertal Barbari bucks, 3-5 mL of trypan blue solution could fill almost 80% of seminiferous tubules. Thereafter, in Experiment-1, the effect of different busulfan doses (mg/kg) i.e. 0 [negative control, Group (Gr) 1; 0 mg/kg-MT], 1 (Gr 2; 1 mg/kg-MT), 2 (Gr 3; 2 mg/kg-MT), and 3 (Gr 4; 3 mg/kg-MT) were studied. Further, in Experiment-2, sterilizing effects of busulfan infusion through two different routes [MT or cavum vaginale (CV)] were compared. Following i.t. busulfan treatment, no adverse physiological effects or body weight loss were detected. The histological analyses demonstrate a dose-dependent depletion of Gc with almost complete loss of Gc and spermatogenic activities in Gr 3 and 4, and extensive fibrosis in Gr 4. A considerable suppression of spermatogenesis marked with devoid of endogenous spermatogonial population and absence of significant (P > 0.05) effect on key hematological variables were observed in 2 mg/kg-MT Gr. These findings coupled with the results of significant (P < 0.05) down-regulation of marker genes of undifferentiated spermatogonia (THY-1 and PLZF), Gc pluripotency (UCHL-1, OCT-4, and DDX-4), and adhesion (E-cadherin and ß-integrin); up-regulation of apoptotic genes (ID - 4 and BCL-6), and unchanged expression of Sertoli cell marker (vimentin), confirmed the safe and efficient depletion of endogenous Gc in 2 mg/kg-MT Gr. Furthermore, the effect of busulfan infusion on scrotal-testicular biometry, endocrine variables (plasma cortisol and testosterone), and Gc removal was more evident when busulfan was infused into MT than into CV. Overall, the results demonstrated that 2.0 mg/kg is an optimal single dose of busulfan when infused into the MT under USG guidance for the preparation of pre-pubertal recipient bucks. Overall, this study provides a basis to prepare suitable recipients through providing an available niche for efficient Gc transplantation in goats.

Status of Beta Defensin-1 and its Effect on Post-thaw Semen Fertility Gene Expression in Indian Goat Breed.

BACKGROUND: Defensins are antimicrobial peptides and uniformly spans the entire sperm surface and is not exclusive to a specific domain. Goat ß-defensin-1 helps in initiation of motility and capacitation of sperm. OBJECTIVE: To know the status of ß-defensin-1 in blood, semen and its effect on post thaw fertility gene expression in Indian goat breeds. MATERIALS AND METHODS: Semen was extended and divided for estimation of ß-defensin-1 and cryopreserved having different concentrations of ß-defensin-1. RESULTS: Bet defensin-1 concentration (pg/mL) in neat semen, sperm pellet and seminal plasma was significantly higher (P< 0.05) in goat breed Barbari followed by Jamunapari and Jakhrana. ß-defensing-1 was also high in Jakhrana blood followed by Barbari and Jamunapari. The post thaw motility, live sperm, acrosome intactness and hypo osmotic swelled sperms were significantly higher (P< 0.05) with 10 ng/mL ß-defensin in the semen dilutor. CONCLUSION: Beta defensin (10 ng/mL) in semen dilutor may be used as immuno-modulator to get better post thaw quality suitable for artificial insemination.

Steady-State Tissue Oxygen Distributions Calculated by a Green's Function Method and a Finite Difference Method: A Comparison.

Simulations that are meant to determine the steady-state distribution of a diffusible solute such as oxygen in tissues have typically used finite difference methods to solve the diffusion equation. Finite difference methods require a tissue mesh with enough points to resolve oxygen gradients near and between discrete blood vessels. The large number of points that are typically required can make these calculations very slow. In this paper, we investigate a numerical method known as the Green's function method which is not bound by the same constraint. The Green's function method is expected to yield an accurate oxygen distribution more quickly by requiring fewer mesh points. Both methods were applied to calculate the steady state oxygen distribution in a model simulation region. When the Green's function calculation used meshes with 1/2, 1/4 and, 1/8 of the resolution required for the finite-difference mesh, there was good agreement with the finite difference calculation in all cases. When the volume of the domain was increased 8-fold the Green's function method was able to calculate the O2 field in 22 minutes, whereas the finite difference calculation is expected to take approximately 1 week. The number of steps required for the Green's function calculation increases quadratically with the number of points in the tissue mesh. As a result, small meshes are calculated very quickly using Green's functions, while for larger mesh sizes this method experiences a significant decrease in efficiency.

Molecular expression and identification of caprine estrogen receptor gene 1 for fertility status in bucks.

Estrogen and its receptors are essential for sexual development and reproduction. Oestrogen receptor alpha (ERα) is a nuclear receptor activated by the hormone oestrogen. In male, ERα is encoded by the gene ESR1 (oestrogen receptor1) responsible for better fertility. ESR1 is involved in the reabsorption of luminal fluid during the transit of spermatozoa from the testis to the head of the epididymis which is important for their survival and maturation during epididymal storage. The absence of ESR1 leads to reduced epididymal sperm content, reduced sperm motility and fertilizing ability. The present study was undertaken to investigate the expression and presence of ESR1 gene in fertile and low-fertile male goat breeds. We identified ESR1 gene through various molecular tools. Genotyping was carried out by high resonance melting analysis using Roche Light Cycler 480(LC-480) system and found three different genotypes. Genotypic frequency-AA (blue-0.67), BB(Red-0.2), AB(Green-0.08) with allele frequency A(0.71 and B (0.29). The predominance of this gene in head of epididymis in fertile bucks was confirmed by SDS-PAGE, Western blotting and immunohistochemistry. From the results, we corroborated that the present study provides a useful and effective way to predict male fertility in goat breeds, which in turn increases the percentage of fertility in flock leading to more number of offspring in a kidding season.

Relationship of foetal number and parity in Barbari goats to plasma profile of caprine pregnancy-associated glycoprotein (caPAG) during gestation and the early postpartum period.

This study was conducted to characterise pregnancy-associated glycoprotein (caPAG) in peripheral plasma during gestation and postpartum periods of nulliparous and multiparous does with one or two foetuses using a caPAG specific two-step sandwich ELISA system. Earliest time-points for detection of pregnancy and foetal number with appropriate cut-off values were identified. Plasma samples from 15 pregnant (multiparous: n = 8; nulliparous: n = 7; during pregnancy and postpartum period) and six non-pregnant (during oestrous cycle) goats were collected and analysed. Mean caPAG concentration was greater than the threshold for pregnancy detection (S-N = 0.40) on d22, peaked on d45 and remained unchanged until parturition. From d45 until parturition, caPAG concentration in multiparous does with two foetuses was 1.4 to 1.8 fold greater (P < 0.001) than those with one foetus. For the ELISA, 0.83 (S-N) was the most appropriate cut-off to differentiate does with two from those with a single foetus with an overall sensitivity and accuracy of 88.9% and 84.7%, respectively. Circulating caPAG concentration in multiparous goats was greater (P < 0.05) compared with nulliparous goats during the early pregnancy and postpartum periods. After parturition, caPAG concentrations markedly decreased and were basal within 14 days postpartum. In conclusion, using the caPAG specific ELISA, results indicated there were unique gestational and postpartum profiles for caPAG concentrations that are affected by number of foetuses and parity of the doe. The marked decrease in concentration of caPAG following parturition indicates there would not be compromising of the detection of subsequent pregnancies in goats using this technique.

Effects of different activation protocols on cleavage rate and blastocyst production of caprine oocytes.

The present study was undertaken to assess the effect of different chemical activators along with 6-DMAP on in vitro matured caprine oocytes. From 4332 ovaries, 14235 cumulus oocyte complexes (COCs) were collected which were matured in TCM-199 medium containing follicle stimulating hormone (FSH) (5 µg/ml), Leutinizing hormone (LH) (10 µg/ml), oestradiol-17ß (1 µg/ml) supplemented with 10% fetal bovine serum, 10% follicular fluid and 3 mg/ml bovine serum albumin (BSA) at 38.5°C and 5% CO2 in an incubator under humidified air for 27 h. In group 1 (control), 3117 in vitro matured oocytes were co incubated with sperms for 18 h in ferttalp medium. In group 2, 3563 in vitro matured oocytes were activated with 7% ethanol for 5-7 min followed by treatment with 2.0 mM DMAP for 4 h in mCR2aa medium. In group 3, 3109 in vitro matured oocytes were activated with 5 µM ionomycin for 5-7 min followed by treatment with 2.0 mM DMAP for 4 h in mCR2aa medium. In group 4, 3455 in vitro matured oocytes were activated with 5 µM calcium ionophore for 5-7 min followed by treatment with 2.0 mM DMAP for 4 h in mCR2aa medium. Oocytes were cultured in 50 µL drops of research vitro cleave (RVCL) medium for embryo development. The cleavage rate, morula and blastocyst production in group 1, 2, 3 and 4 were 26.07 ± 2.37%, 14.91 ± 2.91 & 1.45 ± 0.71%, 49.57 ± 3.79%, 20.07 ± 2.38% & 5.29 ± 1.42%, 50.18 ± 3.59%, 15.26 ± 2.87% & 1.85 ± 0.72% and 80.26 ± 2.30%, 35.33 ± 2.67 & 7.10 ± 0.89%, respectively. These results indicated that the activation of in vitro matured oocytes by 5 µM calcium ionophore for 5-7 min followed by treatment with 2.0 mM DMAP for 4 h is most favorable for parthenogenetic caprine embryos production.

Study of TALP and TRIS citrate medium on caprine sperm capacitation and subsequent in vitro embryo production.

The aim of the present investigation was to compare Tyrode's albumin lactate pyruvate (TALP) medium and TRIS citrate medium for capacitation of caprine sperm. In experiment 1 capacitation was assessed by chlortetracycline assay and in experiment 2 with in vitro fertilization and embryo development. In experiment 2, cumulus oocyte complexes (COCs) recovered by slicing the caprine ovaries were matured in maturation medium for 27 h in humidified atmosphere at 38.5°C with 5% CO2. After 27 h of culture a total of 2480 in vitro matured oocytes were selected and randomly divided into two groups. Group 1 (n=1124) matured oocytes were fertilized by the spermatozoa capacitated in TALP medium and in group 2 (n=1356) matured oocytes were fertilized by the spermatozoa capacitated in TRIS citrate medium. The results of experiment 1 indicated a comparatively more number of sperms with Chlortetracycline (CTC) Pattern B in TRIS citrate than TALP medium (55.32 ± 0.91% vs 47.96 ± 0.20%). In experiment 2, the cleavage rate and blastocyst production were higher following capacitation of spermatozoa in TRIS citrate than TALP medium. In conclusion, TRIS citrate can be used as an alternative and effective media for sperm capacitation to get higher cleavage rate and blastocyst production in goat.

Estrogen receptor gene 1 expression in caprine and its effect on fertility.

The present study was undertaken to analyze the expression pattern of estrogen receptor 1 gene (ESR1) in Barbari bucks (fertile and non-fertile) identified on the basis of seminal quality traits and fertility trials. RNA was extracted from the spleen by Trizol method. The expression pattern of ESR1 gene was analyzed using real time polymerase chain reaction (RT-PCR). The expression pattern of ESR1 gene was analyzed by RT-PCR (Roche LC-480). Relative quantification by RT-PCR indicated that the ESR1 gene expression showed more fold in fertile bucks as compared to non-fertile.

Molecular expression of caprine estrogen receptor gene 1 in reproductive and non-reproductive tissues.

During the last decades, physiological effects of oestrogens have been increasingly explored by scientists and biotechnologists. Estrogens exert a wide range of effects on a large variety of cell types. Oestrogen and its receptors are essential for sexual development and reproduction. Estrogen receptor alpha is a nuclear receptor activated by the hormone oestrogen. In male, ERα is encoded by the gene estrogen receptor gene 1 (ESR1), responsible for better fertility. The ESR1 is involved in the reabsorption of luminal fluid during the transit of spermatozoa from the testis to the head of the epididymis which is important for their survival and maturation during epididymal storage. The absence of ESR1 leads to reduced epididymal sperm content, reduced sperm motility and fertilizing ability. Therefore, this is a good startby to study the expression pattern of estrogen receptor 1 gene in high-fertile (G1) and low-fertile (G2) bucks of Jamunapari and Barbari breeds identified on the basis of seminal quality traits and fertility trials. RNA was extracted from the tissues by TRIzol method. The identification and expression pattern of caprine ESR1 gene was analysed by real-time PCR (Roche LC-480). Our work shows that the relative quantification by RT-PCR indicates more fold in head of epididymis as compared to spleen of caprine ESR1 gene. Furthermore, the RT-PCR indicated that fertile bucks of Jamunapari breed have more fold value as compared to Barbari breed in respect of reproductive organ.

Effect of Ca Ionophore On Blastocyst Production Following Intracytoplasmic Sperm Injection in Caprine Oocytes.

The aim of the present investigation was to study the effect of calcium ionophore activation on blastocyst production following intracytoplasmic sperm injection (ICSI) in in vitro-matured Caprine oocytes. A total of 470 in vitro-matured oocytes were selected and randomly divided in to three groups. Cumulus oocyte complexes (COCs) recovered by slicing the Caprine ovaries were matured in TCM199 supplemented with 10% foetal bovine serum (FBS) + 10% follicular fluid + FSH (5 µg/ml) + LH (10 µg/ml) + estradiol (1 µg/ml) + EGF (10 ng/ml) + BSA (3 mg/ml) for 27 h in humidified atmosphere at 38.5°C with 5% CO2 in CO2 incubator. After 27 h of culture, selected COCs (n = 470) were separated from cumulus cells by treating with 0.1% hyaluronidase enzyme and passing repeatedly through a fine pipette and randomly divided into three groups. In group 1, (n = 168) matured oocytes were injected with injection micropipette without sperm as control. In group 2, (n = 152) capacitated spermatozoa were injected into cytoplasm of in vitro-matured oocytes through injection micropipette. In group 3, (n = 150) capacitated spermatozoa were injected into cytoplasm of in vitro-matured oocytes through injection micropipette and then activated with 5 µm Ca ionophore for 5 min. The oocytes of all groups were then culture in RVCL media for embryo development. The cleavage rate was observed after 48-72 h of injection. The cleavage rate and blastocyst production in group 1, 2 and 3 were 0.00 and 0.00, 18.42 and 3.57 and 61.33% and 16.30%, respectively. The result indicated that mechanical activation failed to induce cleavage in in vitro-matured Caprine oocytes, whereas chemical activation of intracytoplasmic sperm-injected in vitro-matured Caprine oocytes showed significantly higher cleavage rate and blastocyst production as compare to non-activated oocytes.

Effect of management system and season on semen freezability in Jakhrana bucks.

AIM: The objective of the study was to determine the effect of the management system (intensive and semi-intensive) and season (autumn and winter) on semen freezability in Jakhrana bucks. MATERIALS AND METHODS: A total of 24 Jakhrana bucks of same body weight and age (BW=30 kg, age=1 year) were randomly allotted into two groups, viz., Group I (intensive system, 12 bucks) and Group II (semi-intensive system, 12 bucks). These two groups were statistically tested for their homogeneity with respect to age and BW. Semen was collected twice weekly using an artificial vagina during two seasons: autumn (September-November) and winter (December-February). A total of 240 semen samples (120 from each group and season) were evaluated for post-thaw motility (PTM), viability, abnormality, functional membrane integrity (hypo-osmotic swelling [HOS]) response and acrosomal integrity. RESULTS: The mean values of PTM and acrosomal integrity of spermatozoa were significantly (p<0.01) higher in Group II as compared to Group I. The mean values of viability and abnormality were also differed significant (p<0.05) between groups. However, the mean values of HOS response were found non-significant (p>0.05) between groups. The season showed a significant effect on all parameters except viability and HOS response. The PTM and acrosomal integrity of spermatozoa were significantly (p<0.01) higher in winter as compared to autumn season. Abnormality of spermatozoa was significantly (p<0.05) lower in winter season. CONCLUSIONS: This study indicates that both management system and season influence semen freezability. The semen collected from bucks reared under the semi-intensive system and winter season showed better semen freezability characteristics.

A comparative study of parthenogenetic activation and in vitro fertilization of in vitro matured caprine oocytes.

The aim of the study was to compare the parthenogenetic activation and in vitro fertilization (IVF) of in vitro matured caprine oocytes. A total of 881 cumulus-oocyte complexes (COC's) were collected from 243 ovaries. Oocytes were matured in TCM-199 medium containing eCG (20 IU/ml), hCG (20 IUµg/ml), oestradiol-17ß (1 µg/ml), BSA embryo tested (3 mg/ml) supplemented with 10% fetal bovine serum at 38.5°C and 5% CO2 in an incubator under humidified air for 27 h. Based on cumulus expansion, the maturation rate was 86.86%. Morphological matured oocytes (n=749) were selected, denuded and randomly divided into two groups. Group 1 (n=223) in vitro matured oocytes activated with 5 µm calcium ionophore for 5 min and cultured in mCR2aa medium containing 5 mM DMAP for 4 h. After 4 h of DMAP treatment, the presumptive zygotes were washed and cultured in the embryo culture medium. Group 2 (n=526) in vitro matured oocytes processed for IVF in mTALP using fresh semen of a fertile pure bred adult Sirohi buck and in vitro culture in mCR2aa medium. Development of putative zygotes was observed every 24 h till day 9 post activation or fertilization under inverted phase contrast microscope. The cleavage rate, morula and blastocyst percentage in groups 1 and 2 were 67.36%, 23.07% and 9.23%, and 30.99%, 19.63% and 9.82%, respectively. The results indicated that the cleavage rate was comparatively higher following parthenogenetic activation with ionomycin/6-DMAP than IVF.

Effect of different activators on development of activated in vitro matured caprine oocytes.

This study was designed to compare the effectiveness of different activation treatments for activation of in vitro matured oocytes and their developmental potency in mCR2aa medium so as to obtain maximum number of embryos. A total of 1090 cumulus oocyte complexes (COC's) were collected from 480 ovaries. In vitro matured oocytes were randomly divided into four groups. Group 1 in vitro matured oocytes (n=226) were exposed to 7% ethanol for 5 min followed by treatment with 2.0 mM DMAP for 4 h in mCR2aa medium. Group 2 in vitro matured oocytes (n=294) were exposed to 7% ethanol for 5 min followed by treatment with 10 µg/ml CHX for 4 h in mCR2aa medium. Group 3 in vitro matured oocytes (n=325) were exposed to 7% ethanol for 5 min followed by treatment with 2.0 mM DMAP and 10 µg/ml CHX for 4 h in mCR2aa medium. Group 4 in vitro matured oocytes (n=108) were cultured for 4 h without any chemical treatment in mCR2aa medium (control). The cleavage rate in groups 1, 2, 3 and 4 was 54.42%, 44.55%, 51.69% and 0.00%, respectively. The percentage of morula and blastocyst production in group 1, group 2 and group 3 was 26.01%, 29.77% and 29.76% and 2.43%, 1.52% and 1.78%, respectively. These results suggest that the activation of in vitro matured oocytes by 7% ethanol for 5 min followed by treatment with 2.0 mM DMAP for 4 h in mCR2aa is most favorable for parthenogenetic caprine embryos production.

In silico investigation of a KCNQ1 mutation associated with familial atrial fibrillation.

Mutations in transmembrane domains of the KCNQ1 subunit of the I(Ks) potassium channel have been associated with familial atrial fibrillation. We have investigated mechanisms by which the S1 domain S140G KCNQ1 mutation influences atrial arrhythmia risk and, additionally, whether it can affect ventricular electrophysiology. In perforated-patch recordings, S140G-KCNQ1+KCNE1 exhibited leftward-shifted activation, slowed deactivation and marked residual current. In human atrial action potential (AP) simulations, AP duration and refractoriness were shortened and rate-dependence flattened. Simulated I(Ks) but not I(Kr) block offset AP shortening produced by the mutation. In atrial tissue simulations, temporal vulnerability to re-entry was little affected by the S140G mutation. Spatial vulnerability was markedly increased, leading to more stable and stationary spiral wave re-entry in 2D stimulations, which was offset by I(Ks) block, and to scroll waves in 3D simulations. These changes account for vulnerability to AF with this mutation. Ventricular AP clamp experiments indicate a propensity for increased ventricular I(Ks) with the S140G KCNQ1 mutation and ventricular AP simulations showed model-dependent ventricular AP abbreviation.

Effects of streptozotocin-induced diabetes on connexin43 mRNA and protein expression in ventricular muscle.

Abnormal QT prolongation with the associated arrhythmias is a significant predictor of mortality in diabetic patients. Gap junctional intercellular communication allows electrical coupling between heart muscle cells. The effects of streptozotocin (STZ)-induced diabetes mellitus on the expression and distribution of connexin 43 (Cx43) in ventricular muscle have been investigated. Cx43 mRNA expression was measured in ventricular muscle by quantitative PCR. The distribution of total Cx43, phosphorylated Cx43 (at serine 368) and non-phosphorylated Cx43 was measured in ventricular myocytes and ventricular muscle by immunocytochemistry and confocal microscopy. There was no significant difference in Cx43 mRNA between diabetic rat ventricle and controls. Total and phosphorylated Cx43 were significantly increased in ventricular myocytes and ventricular muscle and dephosphorylated Cx43 was not significantly altered in ventricular muscle from diabetic rat hearts compared to controls. Disturbances in gap junctional intercellular communication, which in turn may be attributed to alterations in balance between total, phosphorylated and dephosporylated Cx43, might partly underlie prolongation of QRS and QT intervals in diabetic heart.

Dose dependent effect of GnRH analogue on pregnancy rate of repeat breeder crossbred cows.

The aim of this study was to investigate the effect of treating repeat breeder dairy crossbred cows with different doses of GnRH analogue through i.m. at the time of artificial insemination, on pregnancy rates from their first service after treatment and overall pregnancy rates. One hundred and thirty seven crossbred dairy cows with a history of repeat breeding and eligible after 6-8 infertile services but clinically free of diseases were selected for the study. The animals were randomly divided into three groups. Group 1 (n = 55) cows were treated intramuscularly with each 20 microg Buserelin-acetate (Receptal, Hoechst Roussel Vet GmbH) at the time of artificial insemination. Group 2 (n = 40) cows were treated intramuscularly with each 10 microg Buserelin-acetate at the time of artificial insemination. Group 3 (n = 42) cows were treated intramuscularly with saline as control at the time of artificial insemination. The first service pregnancy rates in Groups 1-3 were 45, 25 and 17%, respectively. Similarly, the overall conception rates in Groups 1-3 were 87, 58 and 48%, respectively. The results indicated that the pregnancy rate in crossbred cows could be improved by the GnRH treatment. The higher dose of GnRH significantly increased (P < 0.05) the first service as well as overall pregnancy rate in a dose dependent manner in repeat breeder crossbred cow bred previously 6-8 times unsuccessfully.