Efficiency of Two Protocols of Resynchronization of Estrus and Ovulation in High-Producing Dairy Cows at Peak Lactation
Milan ĐorđevićJovan BlagojevićMiodrag RadinovićMarko CincovićJelena MaletićMario KreszingerMilan Maletić
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Abstract The reproductive efficiency of the cows was monitored after two resynchronization protocols: Ovsynch (OVS) and Double Ovsynch (DOS). The research initially included 70 HF cows who entered the first synchronization protocol – Presynch. Cows that did not conceive after the first synchronization were divided into two groups and introduced to two resynchronization protocols. In the first group of cows (n=35), the DOS protocol began with the application of GnRH on day 22 after the Presynch TAI (Timed Artificial Insemination), and seven days later pregnancy check-up was done and PGF 2α was applied only to non-pregnant cows (n=23), which remained in the study. In the second group of cows, the OVS protocol started on day 32 after Presynch TAI only in non-pregnant animals (n=20). Progesterone (P4) concentration was determined at the time of application of GnRH1, PGF 2α and GnRH2 in both groups of cows, and then 30 days after Resynch TAI, ultrasound pregnancy diagnosis was done. A higher percentage of pregnant cows were recorded in the OVS group compared to the DOS group (45% and 35%, respectively). The concentration of P4 in the serum of cows in the DOS group during the first measurement (GnRH1) was significantly higher than the value in cows that did not conceive (p<0.05), while in the third measurement (GnRH2) the average concentration of P4 in conceiving cows was significantly lower (p<0.001) compared to cows that did not coincive. The open days period was significantly longer in pregnant cows that were resynchronized using the DOS protocol compared to cows from the OVS protocol. In conclusion, the OVS protocol of estrus resynchronization in dairy cows proved to be more successful than the DOS protocol. However, considering the advantages the OVS, it is needed to determine which day of the sexual cycle is the best to start resynchronization.Keywords:
Estrus synchronization
Palpation
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In eleven non-pregnant mares examined for 2 years, oestrous cycle length was 20-6 days (range 13 to 34) excluding any anoestrous periods. The duration of oestrus was 5-7 days (range 1 to 24); from February to May it was 7-6 days (range 2 to 24) and from May to November 4-8 days (range 1 to 10). The majority of ovulations occurred between 16.00 and 08.00 hours and 78% of the mares ovulated within 48 hr of the end of oestrus. Mean follicular diameter was 45 mm on the day of ovulation and there was a 25-5% incidence of multiple ovulations. It was uncommon for oestrus to occur without ovulation, whereas ovulation without oestrus occurred in 6/11 mares, including one mare which ovulated without oestrus on 32/34 occasions. The CL was palpable after ovulation for 8-9 days (range 1 to 18). Dioestrus averaged 15-4 days (range 6 to 25). Ovulations during dioestrus, unaccompanied by signs of oestrus, occurred in 10/11 mares but cycle length was not affected. A syndrome of spontaneous prolongation of the CL, accompanied by follicular activity, without any signs of oestrus for periods of 2 to 3 months was observed in six of the mares.
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Estrus synchronization
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Abstract This study aimed to determine the pregnancy rate of artificial insemination (AI) in beef cows after estrous synchronization using prostaglandin (PGF2a). A total of 398 beef cows were used in the present study; 183 in Bantaeng (BT) region and 215 beef cows in Bulukumba (BK) region, respectively. Out of 398 beef cows, 201 were randomly subjected to estrous synchronization in both regions and inseminated after estrus was detected, and the remaining 197 beef cows were inseminated after natural estrus. The data were compared using the Chi-square test. The results of this study showed that the overall pregnancy rate with and without estrous synchronization was 52.8%; consisted of 58.7% and 46.7% of pregnancy rate with and without estrous synchronization, respectively. The pregnancy rate of AI in beef cows after synchronized the estrus in BT was significantly (P<0.05) lower than in BK (51.0% vs. 66.3%), but did not show significantly different for the pregnancy rate in beef cows without estrous synchronization. In the BK region, the pregnancy rate of the cows synchronized the estrus was significantly (P <0.05) higher than without estrous synchronization but did not in BT region. It can be concluded that there was a tendency that beef cows synchronized the estrus had a higher 12.0% pregnancy rate than without estrous synchronization.
Estrus synchronization
Beef Cattle
Prostaglandin f
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A nonapeptide (D-Ser (TBU)6-EA10; Hoe 766; Hoechst AG), 25 times more potent than LHRH in LH and FSH releasing activity, was administered (2 µg s.c. in 0.5 percent gelatin) to ewes on Day 1 (n=51), Day 12.5 (n=48) or Day 14.5 (n=39) of the estrous cycle (Day 0 = day of estrus). A control group (n=23) was not treated. Ovulation rate at the estrus or time of expected estrus following treatment was increased (P<0.05) in ewes injected on Day 12.5 (1.36) compared to ewes in the control group (1.09) and ewes injected on Day 1 (1.13), but not in ewes (0.05
Gonadotropin
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Objective: To observe the function of half-ration urine LH in the pregnancy guidance of the infertility couples, and in the arranging correctly precise ovulation prediction in the assisted reproduction technology of artificial insemination. Methods: Use half-ration urine LH, observing the changes of the urine LH before and after the ovulation. Choose the optimal time of ovulation, with the transvaginal scanning and the detection of the serum LH value. Results: Among 180 patients' ovulation cycles, 150 of them belong to therapy cycles, 30 to natural cycles, thus get preferable according rate of 86.21%. Conclusion: Using the convenient means of half-ration urine LH together with the morphologic of the transvaginal scanning, choose the optimal time of ovulation for the artificial insemination, solve the problem of precisely confirming half-ration urine LH together with the morphologic of the transvaginal scanning, choose the optimal time of ovulation for the artificial insemination, solve the problem of precisely confirming the ovulation day.
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Estrus synchronization is an important technique in AI, Several methods have been used in cow estrus synchronization. However, previous reports showed that the efficiency of estrus synchnization was different due to the situation of the cows as well as other conditions. In the present study, the effect of GnRH on estrus synchnization of cow was examined and compared with that of using PGF 2α method, 153 cows were randomly divided into 3 groups. The first group were treated with a injection of PGF 2α,the second group were treated with twice injection of PGF 2α and the third were treated with twice GnRH and once PGF 2α injection. The results showed that the estrus rates of the three groups were 32.65%(16/49), 45.59%(31/68) and 91.30%(42/46),respectively. The estrus rate of the third group was significantly higher than those of the other group(P0.05).
Estrus synchronization
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Progesterone in oil solution injected into mares intramuscularly in midcycle blocked estrus and ovulation at levels of 100 mg. per day or higher. Fifty milligrams per day prevented estrus but not ovulation. The interval from end of treatment to estrus appeared to depend upon dosage, and the effects on subsequent cyclic patterns were confounded by season of the year. Neither 50 nor 100 mg. per day stopped estrus or blocked ovulation when treatment was started on day 1 of estrus. Injection of 100 mg. per day of progesterone in oil delayed postpartum estrus and ovulation, but 50 mg. per day did not. A single injection of 500 mg. of crystalline progesterone did not delay postpartum estrus and ovulation consistently. MAP administered orally to mares in midcycle or to mares showing erratic estrus in the early breeding season failed to inhibit estrus or ovulation at levels of from 400 to 1782 mg. per day. Melengestrol acetate was ineffective when fed at 10 or 20 mg. per day to cycling mares. Neither a single injection of 500 mg. of crystalline MAP nor daily injection of 100 mg. per day in oil solution was effective in blocking postpartum reproductive activity.
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