جستجوی مقالات مرتبط با کلیدواژه "gnrh" در نشریات گروه "علوم دام"

Gonadotropin-releasing hormone (GnRH) is a key regulatory molecule of the hypothalamus–pituitary gonadal axis which induces transcription of luteinizing hormone (LH) from the anterior pituitary. Research has shown that estrogen plays an important role in regulating GnRH. Also, recent experiments indicated that Vitex agnus-castus (VAC) has high levels of phytoestrogen. Hence, this research was performed to investigate the effect of Vitex Agnuse Castus (VAC) fruit powder on GnRH and LH genes expression in laying hens using Real time qPCR technique. For this purpose, 90 Hy-line W-36 leghorn (at 72 to 80 weeks old) were used in a completely randomized design with 3 treatments, 5 replicates and 6 hens per replicate for 56 days as an experimental period. The three experimental treatments were: 1- control diet (basal diet without any additives), 2- basal diet plus 1% VAC fruit powder, 3- Basal diet plus 2% VAC fruit powder. At the end of the experiment one hens were slaughtered and their hypothalamus was rapidly separated and transferred to the laboratory with liquid nitrogen. Then, RNA was extracted and used for cDNA synthesis. Finally, GnRH gene expression was evaluated by Real-Time qPCR. The ANOVA results showed that GnRH gene expression was significantly increased in treatment 3 (diet containing 2% VAC) compared to the control and 1% VAC groups (P <0.01). While, addition of 1% VAC fruit powder to diet had no significant effect on GnRH gene expression (P> 0.05). Furthermore, addition of 1 or 2 % VOC fruit powder had no significant effect on LH gene expression (P> 0.05). The results of this study showed that the addition of VOC fruit powder fruit powder up to 2% level could not affect the pituitary-hypothalamic axis of laying hens at 72 to 80 weeks old.

Estrus synchronization is an important technique in management of reproductive function in ewes. The objective of this study was to evaluate the effect of using combination of PMSG and GnRH hormones on estrus synchronization during the breeding season in Farahani ewes. Forty mature Farahani ewes, weighting 48.97±0.55 kg, BCS 3.04±0.3, were used in this study. The experimental ewes were synchronized using CIDR for a period of 10 days and injected 2 ml PGF2α at day 0 and these ewes randomly assigned to four groups. The control group (group 1; n=10) did not receive any treatment. Ewes in group 2 were injected with 150 IU PMSG and 1 ml Buserellin acetate after CIDR removal. The group 3 ewes injected with 100 IU PMSG and 2 ml Buserellin acetate after CIDR removal. The group 4 of ewes were injected with 300 IU PMSG and 0.5 ml Buserellin acetate after CIDR removal. Estrus detected after CIDR removal, then, the ewes were mated with Farahani rams. After parturition, the reproductive parameters of ewes were recorded. The estrus rate was constant in all groups. The lamb weight in group 4 was significantly different (P>0.05) compared with other groups. Pregnancy rate was not significantly meaningful among treatments. The lowest glucose and progesteron concentration was achieved in group 4 that was significantly different (P > 0.05) compared to other groups. The data of birth weight also didn’t show significant differences (P>0.05) between the treatment groups. There was no significant difference in abortion and stillbirths between treatments (P˃0.05). The results showed that the combination of two PMSG and GnRH hormones in the estrus synchronization program could increase the lambing rate up to 0.7.

Estrus synchronization is a valuable management tool that has been employed in enhancing reproductive efficiency in ewes. This study was conducted to investigate the reproductive performance of ewes with short and long-term estrous synchronization programs accompanied by eCG or GnRH during the non-breeding season. A total of 48 Afshari ewes were randomly selected and divided into two groups. In the first group, ewes received intravaginal sponges for 7 days (n=24) and in the second group ewes received intravaginal sponges for 14 days (n=24). At the time of sponge removal, each group was divided into two subgroups of 12 ewes; intramuscularly received 500 IU eCG and 100 IU GnRH, respectively. Blood samples were collected at the time of sponge removal. Considering plasma progesterone concentrations, there were no significant differences between 7 and 14 days groups (P>0.05). In 14 days group, estrus and lambing rates of eCG subgroup were significantly higher than those in GnRH subgroup (P <0.05). Conception and lambing rates of eCG subgroup in 7 days group were significantly higher than those in GnRH subgroup in 14 days group (P<0.05). In 7 days group, twinning rate of eCG subgroup was significantly higher than that of GnRH subgroup (P<0.05). Therefore, in this study, short-term estrus synchronization programs (7 days) and injection of 500 IU eCG simultaneous with sponge removal exhibited the best reproductive performance in Afshari ewes during non-breeding season.

Increment of ovulation rate in farm animals improves reproductive performance through increasing in litter size and fecundity rate. Estrus synchronization or the induction of estrus is a valuable management tool for increasing the pregnancy rate in goats. Stimulation of ovulation using different methods can improves reproduction performance by increasing the proportion of goats having twin ovulations and thereby increase kidding percentage (Khaldari 2008; Rahman et al. 2008). It has been suggested to use new reproductive approaches such as controlling and synchronizing of estrus and using hormones by applied Artificial Insemination (AI) to increase prolificacy leading to gain practical and economical advantages. Recently, Progesterone or its analogues is generally used to synchronize estrous during the breeding and non-breeding season. Administration of gonadotropins such as equine Chorionic Gonadotropin (eCG) after stopping progesterone treatment, causes an increase in rate of ovulation (Lopez-Sebastian et al. 2007). Also using Gonadotropin Releasing Hormone (GnRH) with eCG leads to a raise in ovulation rate and litter size in different goats breed (Akifcam and Kuran 2003). The objective of this study was to improve the reproductive performance using GnRH and eCG administration in breeding season.
Material and The experiment was carried out on 150 mature (2–5 years of age), non-lactating does with a body weight varying between 37 and 39 kg. The current study was performed in the natural breeding season under natural photoperiod environment. Synchronization of estrus was done by inserting intravaginal sponges containing 40 mg flugestone acetate (FGA, Chrono-Gest, Intervet International B.V., Holland) for 16 days. Goats were randomly assigned to three groups. The control group (T1) exposed to Khalkhali bucks without any treatments for mating after sponge removal. Goats in second (T2) and Third (T3) groups were injected intramuscularly 400 IU eCG (Serogonadotropin®, Biowet S.A., Poland) and 400 IU eCG with 50 mg GnRH (Vetocept®, Aboureyhan Co., Karaj, Iran) respectively in sponge removal time. Then the does were mated naturally with Khalkhali bucks. Five fertile Khalkhali bucks were introduced to each group twice a day, starting about 24 h after CIDR withdrawal, and left with them for estrus detection and natural mating. Does were observed continuously for 3 h when bucks were introduced to them and their mating were recorded. The date of birth, numbers of kids born per does and weight of each kid were recorded at kidding time. Reproductive parameters, including pregnancy rate, kidding rate, fecundity rate, twinning rate was determined as well. Blood was sampled from the external jugular vein into heparinized test tubes. The first blood samples were collected before inserting intravaginal sponges, the second, 7 days after inserting sponges and the third, one day after intravaginal sponge withdrawal. Samples were immediately transferred to the lab and centrifuged in the tubes for 15 min at 1000 ×g to separate the plasma. Plasma samples were stored at −20 ◦C for less than 2 months until analyzed for estrogen and progesterone concentrations. All assays were carried out in duplicate. The reproductive parameters were analyzed by ProcGenmod using SAS 9.2 in completelyrandomized design. The means of all reproductive traits were compared by using Chi-Square test. Born weight of kids and hormone concentration data were analyzed using the General Linear Models procedure of SAS and P 0.05) in breeding season. Control group had lower fecundity rate (106%) than the treatment groups (158% and 188 % in second and third groups respectively). Lambing rate in 1 to 3 treatments were calculated 113, 175 and 177% respectively that the treatment groups had higher (P 0.05). There was no significant difference in plasma estrogen and progesterone concentrations between treatments as well (P>0.05). eCG has biological activity of FSH and LH hormones and luteinizing effect of eCG promotes the maturation of follicle that lead to increase the production of estrogen hormone. Estrogen is effective in causing the estrous cycle (Godfery et al. 1997). Results of the current study showed that the injection of 400 IU eCG after sponge removal had no effect on kidding rate and pregnancy rate. But Zaiem et al (1996) observed that the goats treated with eCG had a higher pregnancy rate compared to the control group. Although some studies have reported that administration of eCG can improve the kidding rate and pregnancy rate in breeding season (Kermani Moakhar et al. 2012) as well as non-breeding season (Husein and Ababneh 2008). On the other hand, some studies reported that eCG has negative effects on pregnancy rate (Zeleke et al. 2005; Menchaca and Rubianes 2004). In the current study, treatment with eCG and eCGᩴ increased twinning rate. This result agrees with those reported by Ali et al (2007). Zarkawi et al (1999) reported that using eCG at CIDR withdrawal increased twinning rate from 7% in control group to 30% in treatment group. Also they observed no significant difference in twinning rates for high eCG doses. In another study using eCG in breeding season led to significant increase in twinning rate (61.9% vs 29.2%), lambing rate (86.2% vs 68.6%) and fecundity rate (127.6% vs 71.4%) compared with the control group (Koyuncu and Ozis Altıcekic 2010). These results were similar to the findings in the present study. There was no significant difference in weight of kids at kidding between treatments groups and control and this result shows that weight of kids was not affected by hormones treatments.
In conclusion, using of synthetic hormone caused improvement of reproductive efficiency of Khalkhali goat in breeding season.

The objective of this study was to investigate effect of different time of GnRH administration and CIDR insert after artificial insemination (AI) on fetus Loss, AI interval and conception rate in Holstein dairy cows. Multiparous high-yield dairy cows (> 30 Kg/d, n= 550) were randomly assigned into five groups. Groups were: 1- GnRH injection on day 5 after AI, 2- GnRH injection on day 11 after AI, 3- GnRH injection on day 13 after AI, 4- GnRH injection on day 5 and 11 after AI and 4- Controlled internal drug release (CIDR) devices were inserted on day 5 after AI and removed on day 14 after AI. Ultrasonography were used for consider ovary status and pregnancy diagnosis at d 32 after AI. Pregnancy was characterized by the presence of an embryo, corpus luteum and fluid in uterus horn. Cows diagnosed pregnant at 32 d were re-examined at 70 d after AI to confirm pregnancy. Pregnancy loss was considered to have occurred when a cow was diagnosed pregnant at 32 d after TAI and not pregnant at 70 d. Results showed percentage of cows that showed estrus at 19-24 d after AI was lowest in G5,11 (20.0 %) cows compared to GnRH injection on day 5 after AI (31.5 %), GnRH injection on day 11 after AI (25.7 %), GnRH injection on day 13 after AI (26.5 %) and CIDR group (32.7 %, P = 0.04). Percentage of cows that did not show estrus until day 34 after AI was lowest in CIDR group (20.6 %, P= 0.01) but there was no difference between other groups (average 42.6 %, P = 0.65). A greater (P = 0.01) percentage of cows that received GnRH injection on day 5 and 11 after AI were pregnant at 32 d (50.0) and 70 d (46.2 %) after AI compared to other groups. Pregnancy loss was lowest in CIDR group (P = 0.04). In conclusion GnRH injection on day 5 and 11 after AI compared to other methods improved pregnancy rates.

The objective of this study was to consider effect of three different time of starting Ovsynch after Artificial Insemination, on synchrony parameters, pregnancy loss and fertility in Holstein cows. Multiparous cows (> 30 Kg/d, n = 450) randomly assigned to one of three groups. Groups according to time of starting Ovysnch were as follows: 1- Starting Ovsynch on day 25 after AI, 2- Starting Ovsynch on day 28 after AI and 3- Starting Ovsynch on day 32 after AI. All cows received an injection of GnRH at time of starting Ovsynch regardless of their pregnancy status, and cow’s diagnosed not pregnant using transrectal palpation received an injection of PGF2alpha seven days later and continued the protocol to receive an injection of GnRH 56 h after PGF and TAI 16 h later. Ultrasonography used to determine response to three injection of Ovsynch, pregnancy diagnosis at first check (32±3 after AI) and second check (65±4 after AI). Results showed response to first GnRH of Ovsynch and ovulatory response to second GnRH of Ovsynch affected by time of starting Ovsynch (P = 0.03). Proportion of cows responded to first GnRH of Ovsynch in group started Ovysnch on day 32 after AI (74.0%) was higher compared to groups started Ovsynch on day 25 (46.0%) or 28 (50.0%) after AI (P = 0.03). Ovulatory response to second GnRH of Ovsynch was greater in groups 32 compared to other groups (P = 0.02). Conception rate at day 32 (P = 0.02) and 65 (P = 0.01) after AI was greater in cows started Ovysnch on day 32 after AI (28.0 and 25.3%) compared to groups started Ovsynch on day 25 (20.6 and 19.3%) or 28 (22.0 and 20.0%) after AI. Cows starting the Ovsynch protocol 32 d after previous AI increased fertility by improving synchrony to the protocol.

Injection of some hormones and antioxidant supplements may improve the reproductive performance of dairy cows during summer season. This study was conducted to evaluate strategies for improving dairy cows’ fertility following artificial insemination in summer season using hormonal and antioxidant compounds. One hundred high producing, multiparous dairy cows were randomly assigned to four groups: 1- Control (without injection of hormone and vitamin), 2- AD3E injection at the time of AI (AD3E), 3- GnRH injection at the time of AI and hCG injection 11 days after AI (GnRH+hCG), and 4- AD3E and GnRH injections at the time of AI and hCG injection 11 days after AI (AD3E+GnRH+hCG). AD3E (25 ml, each ml contain 50000 IU A, 10000 IU D3 and 20 mg E), GnRH (5 ml, each ml contain 5 μg alarin acetate) and hCG (1500 IU) were injected intramuscular. The blood sampling was on days 11, 15 and 19 after AI. The data showed that cows which received vitamin AD3E had more open days and need more insemination services for pregnancy (P<0.05). Cumulative pregnancy rates in the second service and pregnancy rate in day 120 postpartum was affected by the treatments and cows received AD3E had no good condition. Pregnant cows which received GnRH+hCG, had higher (P<0.05) serum progesterone concentration than the other groups on day 19 after AI. The injection of GnRH+hCG reduced (P<0.05) concentration of serum cholesterol and VLDL. However, these cow had higher (P<0.05) glucose, total protein and albumin than that the AD3E group. AD3E injection had adverse effect on reproductive performance of high producing dairy cows in summer season. Although, the injection of GnRH+hCG had no beneficial effect on reproductive performance, but it had some positive effects on blood biochemical parameters.

When dairy cattle are subjected to heat stress, reproductive efficiency declines.To override the suppressive effects of heat stress various environmental and hormonal manipulations have been utilized. The aim of the present study was to evaluate whether the administration of GnRH and hCG on day 5 post-insemination would improve pregnancy rate in mild heat stressed dairy cattle (summer months). All cows were inseminated at estrus and then on days 5 after AI, they were alternately assigned into three groups: GnRH group(n=44)received an IM injection (5ml) of GnRH (GONAbreed®,PARNEL, Australia,) hCG group (n=44) received an IM injection (1ml) of hCG (Pregnyl®, Daru Pakhsh, Iran) and control group (n=36) which did not received any treatment.Pregnancy was diagnosed on day 32-39 after AI by ultrasonography.. The difference in CR among three groups were analyzed by using chi-square and fisher test. CR in GnRH, hCG and control groups were 54/5%, 61% and 58/3% respectively, that weren’t significant difference among three groups (P>0.05). CR within GnRH groups in ≤150 and>150 days open subgroups were 72%, 40% that is statistically significant (P<0.05) and also CR between GnRH and hCG groups based on Open days>15o was 40%, 76% that is statistically significant (P<0.05). CR within control and hCG groups among <3 and≥3number of AI were 80%, 31%, 77% and 39%respectively, that is statistically different(P<0.05). According to the results of this study, the use of hCG after AI in repeat breeder dairy cows in summer months is recommended.