The objective of this study was to compare first service conception rate before and after milking and changes in metabolite and hormones during four times realted to milking in lactating dairy cow. 300 High producing Holstein cows (> 30 Kg/d and BCS) were randomlly selected and assigned into two groups: 1-insemination before morning milking (0700 a. m, n = 150) and 2-insemination after morning milking (0900 a. m, n=150). Milking was performed at 8 a. m. All cows were synchronized with G7G-Ovsynch protocol started at d 30 postpartum. Blood samples collected from subsample of cows (n = 45 per group) and at four times (before milking, with milking, 1 h after milking and 2 h after milking) for measauring glucose, triglyceride, free fatty acids, albumin andcortisol concentrations. Results showed that Glucose, trigyceride, free fatty acids, abumin and cortiso concentrastions were affected by miking time (P<0. 05) and significanty increased with milking compared to before milking (P<0. 05) but significanty decreased 1 h after milking compared to milking and before milking. Conception rate at d 32 and 60 after AI were greater in cows inseminated after milking in comparsin with before milking. In conclusion results of the present study showed insemination of cows after milking compared to before miking resulted in increased fertility.

The objectives of this study were to summarize the effect of sexed semen on conception rate of Esfahan province Holsteins dairy herds based on breeding year, Season, service number and age group of heifers in the time of conception. For conducting this research, the data from 59 herds which was collected by Vahdat cooperation of Esfahan province was used. The data consists of 73115 of heifers inseminated with 3529 sexed semen and 69431 with conventional semen from spring 1991 to spring 2014. Binary distribiution of conception rate was analysed by logistic regression. The results indicated that for all sub-levels of the studied factors, except for the third and fourth service number, and for the unknown used sperms, the conception rate was higher, or, in other words, the ratio of pregnant heifers were significantly higher (P<0.05) than non-pregnants. Only in the fifth and higher service numbers, this ratio was reverse and non-pregnant rate of heifers significantly (P<0.05) were higher than pregnants. The average likelihood of conception rate of spring and summer season (53%) was significantly less (P<0.05) than autumn and winter season with a probability of 55%. The probability of conception rate of service numbers from first to fifth and higher had a descending trend, so that the probability of first service number was 63% significantly higher than others (P<0.05). The average likelihood conception rate of heifers for conventional sperm and sexed sperms was significantly different (P<0.05) and was 58% and 41%, respectively. The highest proportion of pregnant/ non-pregnant animals (75%) was obtained for naturally inseminated service. In conclusion, it seems that when using sexed sperm, different factors affecting conception rate should be take into consideration. So, the results of this research can be useful in the reproduction management of heifers during the use of sexed sperm and also taking into consideration of proper breeding and environmental factors.

The aim of this study was to determine the effect of eCG and oxytocin (OT) on heat and pregnancy rate of Lori-bakhtiari ewes during breeding season. Eighty four ewes, 3 to 4 years old, 65±2.5 kg weight, were received CIDR for 12 days, and at the time of CIDR removal assigned into 3 groups in which received 0, 400 and 500 IU eCG, respectively. Before artificial insemination, the groups divided into 2 subgroups and one of each 2 subgroups received OT (100 IU) intramuscularly. Fifty four hours after CIDR removal the ewes were inseminated and conception rate were recognized via ultrasonography 50 days after artificial insemination. The result of this study showed that eCG injection improves heat rate in comparison to control (78.56 % vs 42.85 %, P<0.05). But OT had no effect on heat rate (50% vs42.85 %, P>0.05). Cervical penetration was higher (88.09% vs 11.90 %, P<0.05) in ewes received OT. Administration of eCG increased conception rate (57.14 % vs 14.28 %, P<0.05). The ewes received OT injection had higher conception rate then control group (42.85% vs 14.28%, P<0.05). The dose of eCG had no effect on pregnancy rate increasement (57.14 % vs 57.14 % without OT and 71.42 % vs 78.57 % with OT, P>0.05). The ewes received eCG and OT had a tendency to higher conception rate (74.99% vs 57.14 %, P<0.1). In conclusion, eCG and OT injection improved conception rate in CIDR synchronized Lori-Bakhtiari ewes during breeding season.

The objective of this study was to examine the effects of administration of Flunixin Meglumine on conception rates and plasma progesterone (P4) changes in Holstein heifers and inhibition of PGF2a synthesis just before luteolysis. 32 Holstein heifers (15-month-old, BW: 357±5kg) Were Synchronized utilizing Ovsynch protocol and artificially inseminated. The heifers were assigned randomly to a treatment group (n=16) and a control group (n=16). The treatment groups were injected intramuscularly three times on days 15.5, 16 and 16.5 post insemination with 1.1 mg/kg bodyweight Flunixin Meglumine whereas control group received placebo. Blood samples were collected on days 15.5, 16 and 16.5 post insemination for analysis of plasma P4 concentrations. Pregnancy was diagnosed on days 30 and 60 by transrectal ultrasonography. On day 30, 10 of the treated heifers were pregnant compared with 4 of the control heifers (P<0.05); on day 60, 9 of the treated heifers were still pregnant compared with 4 of the control heifers (P>0.05). Mean plasma progesterone concentrations on day 16.5 in treated heifers (2.62±0.66 ng/ml-1) was higher than control group (1.87±1 ng/ml-1) but this improvement was not statistically significant (P>0.1). The results of this study support the hypothesis that Flunixin Meglumine is able to inhibit the uterine synthesis of PGF2a and increase the survival of early embryos.

Lactating Holstein dairy cows (n=167) were assigned randomly to four treatments groups. two groups presynchronized with two injection of PGF2a, 14 days apart and then followed with Ovsynch and Heatsynch (presynch-ovsynch or presynch-heatsynch) and two other groups presynchronized with one injection of PGF2a and two day after that receive GnRH 6 d before the first GnRH injection of ovsynch and heatsynch (G6G-ovsynch or G6G-heatsynch). Four blood samples were collected from cows for determination of plasma progesterone concentration. Sample 1 and 2 for determining the cyclic cows and Third samples 24h after PGF of the Ovsynch and Heatsynch protocol were taken to assay blood serum estradiol. The fourth sample was taken at 21 days afetr AI. Transrectal ultrasonography was performed to diagnose pregnant cows 30 d after AI. Mean milk production and BCS around AI time was similar among treatments. Estradiol concentration at proestrus was similar among groups. Although conception rate was higher in Presynch-Heasynch (%53 versus %43 in presynch-ovsynch and G6Gheatsynch and %39 in presynch-ovsynch) but this difference was not significance. There was a significance positive correlation between estradiol conentration and conception rate (0.267) in our study in total but this correlation was higher in G6G-Ovsynch (0.343). This study has shown that there is a positive corrolation between preovulatory estradiol concentation and conception rate in the synchronized dairy cattle.

The present study was designed to investigate the impact of exogenous administration of GnRH (Receptal VETâ, Intervet Pharmaceuticals Ltd., India) on serum progesterone profile and conception rates during mid luteal phase of estrous cycle in buffaloes. Estrus was induced using Cyclix 2 mL. i/m. (Intervet India Pvt. Ltd., India) and animals were bred naturally during observed estrus. The buffaloes (n=40) were grouped as control (n=10) on day 0 and treatment groups (I, II and III, n=10 in each group). GnRH (2.5 Ml) was administrated on day 0, 11 and 13 of estrous cycle. Progesterone concentration was significantly higher (P<0.05; 1.782±0.046 ng/mL) in group I on day 5 and in group II on day 13 (4.514±0.038 ng/mL) and day 18 (6.173±0.015). However, in group III progesterone concentration was significantly higher on day 18 (6.554±0.0993) compared to control on day 5 (1.390±0.587 ng/mL), day 13 (3.770±0.103 ng/mL) and day 18 (5.114±0.009 ng/mL), respectively. Although progesterone concentration increased in all the three treatment groups compared to control, it was significantlymals of group I on days 5, 11, 12, 13 and 18 than non-pregnant animals of same group. Nevertheless, these differences were significant on days 13 and 18 in group II and on day 18 in group III in pregnant animals compared to non-pregnant animals, respectively. Similarly the conception rate was also significantly higher (P<0.05; 80% vs. 60%) in animals at group III compared to those at control. Comparison of data on progesterone profile be-tween pregnant and non-pregnant (within group) animals of various treatment and control groups showed significantly higher levels of serum progesterone in pregnant animals on days 11, 12, 13 and 18 as compared to non-pregnant animals of the same group. Thus, the above study revealed positive impact of GnRH administration on progesterone profile during mid luteal phase of estrous cycle, which could be used to improve fertility in buffaloes.

Heat stress causes reduced fertility and significant economic loss in dairy cattle. To override the suppressive effects of heat stress, various hormonal manipulations have been utilized. The aim of this study was to compare the effect of progesterone (in the form of CIDR) and administration of GnRH after insemination on the conception rate of heat stressed dairy cattle. All cows were inseminated at estrus and were then alternately assigned into three groups on day 5 after artificial insemination (AI): i) GnRH group (n=44) received an IM injection of 500 mg GnRH (GONAbreed, PARNEL, Australia,); ii) CIDR group (n=44) received a CIDR (EAZI-BREED, Hamilton, NZ, containing 1/9 g progesterone) which was removed after a week; and iii) control group (n=36), which did not receive any treatment. Conception was diagnosed on day 32-39 after AI by ultrasonography. Conception rate in GnRH, CIDR and control groups were 54.5%, 54.5% and 58.3%, respectively. The results demonstrated that there was no significant difference among the three groups (p>0.05). These treatments had had no statistically different effects on lactation, milk yield, days in milk and number of AI (p>0.05). Conception rates within GnRH and CIDR groups in <150 and >150 days in milk subgroups were 74.4%, 40.7%, 84.6% and 41.9%, respectively and differed statistically significantly (p>0.05). Conception rate within control and CIDR groups among <3 and >3 numbers of AI were 80%, 31.2%, 84.2% and 32%, respectively, which was statistically significant (p>0.05). According to the results of this study, the use of GnRH and CIDR after AI did not improve conception rates of mildly heat stressed dairy cattle.

It has been demonstrated that heat stress has a detrimental effect on conception rate of dairy cows, via early embryonic death. To reduce heat stress, providing shade, fan, appropriate diet and application of ovulation induction agents (GnRH and hCG) is recomended. Endogen PGF2a has positive effect on ovulation. Repeat Breader. The aim of the present study was to evaluate the role of PGF2a injection on reproductive performance of Repeat Breader (RB) dairy cows in heat stress condition at artificial insemenation (AI). This study was conducted in two large dairy farms in Tehran province during the summer 1386-87. All cows were inseminated (A M -PM) based on heat detection at 12 hours after observed standing heat. Mean temperature and humidity were recorded throughout the study. In this study 150 RB cows were randomly divided into three groups. Group A(n=50) received PGF2a simultaneously with AI, group B (n=50) received GnRH at the time of AI and group C (n=50) did not receive any treatment and served as control. Based on rectal palpation on 40-50 days of AI, 5 cows of group A, 9 of group B and 10 of group C were pregnant. There were not any significant differences among groups (p>0.05). The results revealed that simultanous using of PGF2a or GnRH with AI has no beneficial effects on conception rate in RB cows.