جستجوی مقالات مرتبط با کلیدواژه « Estrus synchronization » در نشریات گروه « دامپزشکی »

Estrus synchronization is a valuable tool in ewe reproductive management.

This study was performed to evaluate the efficiency and determine the best time of eCG injection in short-term synchronization program based on GnRH-PGF 2α in Shal ewes during the breeding season.

One hundred and sixty non-pregnant Shal ewes, aged 2-6 years old were selected and randomly stratified to four equal groups. 25µg Alarelin acetate (GnRH analogue) and 75µg D-cloprostenol (PGF 2α analogue) were injected to all ewes, on days 0 and 5, respectively. The first group (control) did not receive any other treatment. Groups 2 to 4 received 400 IU of eCG, 48 hours before, 24 hours before and concurrent with PGF2α, respectively. Ewes were exposed to fertile rams during 96 hours post PGF2α injection. Blood serum progesterone concentrations were measured just before PGF2α injection and 10 days later.

No difference was observed in the first serum progesterone evaluation among experimental groups (P>0.05). However, progesterone had significantly higher concentrations 10 days after PGF 2α injection in groups 2 and 3 in comparison with groups 1 and 4 (P<0.05). Simultaneous use of eCG with PGF2α led to a higher estrus response in comparison with other groups (P<0.05). During the first day after PGF2α, a higher percentage of ewes in group 2 and 3 exhibited estrus compared with groups 1 and 4 (P<0.05). Conversely, estrus expression was higher 24-48 hours after prostaglandin injection in groups 1 and 4 than the other two (P<0.05). Thus, the interval to estrus was earlier in group 2 and 3 than groups 1 and 4 (P<0.05). No significant differences were detected in terms of conception rate, lambing rate, prolificacy and fecundity among study groups (P>0.05).

Use of eCG in different times (48 and 24 hours before and concurrent with PGF2α) in short-term synchronization program based on GnRH-PGF2α during the breeding season can be effective on estrus indices. Regarding the diversity of sheep's masses in Iran, it seems that acceptable results may be achieved when eCG is used concurrently with PGF2α in short-term protocol.

Low pregnancy rate is one of the important problems in livestock. Therefore managing the process of reproduction in animals by using synthetic hormones and synchronizing increase the pregnancy rate. The aim of this study was to investigate the effect of GnRH on days 10, 11, and 12 after artificial insemination on pregnancy rate of Makui sheep breed. For this propose, 226 ewes were synchronized estrus by using CIDR. After removing CIDR, all ewes were received 400 IU PMSG. After two days, all heat ewes were artificially inseminated with fresh sperms. Ewes were divided into three groups. The control group did not received any hormone. The second group had subgroups D, E and F, that received 20 µg GnRH on days 10, 11, and 12 after AI, respectively. Finally, group G was received 40 µg GnRH on day 12 after AI. Blood samples were collected two days after GnRH injection by using vacuum tubes. The sera concentrations of glucose, urea, total protein, phosphorus, and progesterone were measured. To analyze the dependent and discrete variables, GLM and FREQ procedure of SAS software were used, respectively. The achieved results showed that the effect of GnRH on plasma concentration of progesterone was significant (p<0.01). There was a significant difference in pregnancy rate between third group with others groups (p<0.01). The maximum rate of pregnancy was related to the third group. It be concluded that, injection of 40 µg GnRH hormone on the day 12 after insemination improves pregnancy rate.

To investigate the effect of melatonin on reproductive parameters in the Shall ewes, out of breeding season, 60 multiparous ewes (maximum 3 parity), were studied in a randomized complete block design. The animals divided into 4 groups of 15 ewes. The control group did not receive any hormone. In the melatonin group, Regulin containing 18 mg of melatonin were implanted at the base of the ear, for 35 days. In CIDR group, 500 IU PMSG was injected, 8 days after removal. In the CIDR plus melatonin group, 35 days after implanting the Regulin, insertion of CIDR was done for 8 days and 500 IU PMSG injected at the removal time. After performing estrus synchronization in all 4 groups, 4 fertile rams introduced to ewes for 5 days. To increase the pregnancy rate, After 15 days of separation between ewes and rams, introducing the rams to ewes was repeated. Reproduction parameters recorded and analyzed by Duncan test (SAS software) at the level of 95% confdence interval. There were no signifcant differences between mean weight of lambs in all 4 groups (p>0.05). Results showed that the number of lambs born in the melatonin group were signifcantly higher than the other groups (p<0.05). In melatonin group, the performance of service per conception and conception rate were better than the other groups and signifcant statistical differences were observed (p<0.05). The parameters of fecundity and conception rates were signifcantly different between the groups. Our fndings showed that administration of melatonin in ewes, out of the breeding season, is effective on improvement of the reproductive parameters. As the administration of melatonin implants is easier than other estrus synchronization methods, produces no vaginal contamination and decreases the cost of management, we recommend melatonin implantation to improve the reproductive parameters in ewes.

Inbreeding is one of the major problems of small size herds of red deer in refuge wildlife parks. The aim of the present study was to use estrus synchronization technique in red deer (Cervus elaphus) based on natural mating to control the dominancy and social rank of stags and inbreeding. In this study, hinds (n=6) were captured and caged at breeding season (early October) in Semeskande Wild Life Refuge Park. The captured hinds were treated with intravaginal progesterone devices (CIDR) for 12 days, followed by injection of 250 IU PMSG at the time of CIDR withdrawal. After 48 hours, all 6 hinds were released from cages. In estrus phase, the chase sequences started and the old dominant stag could not control all of the hinds in his territory so the two other young stags successfully mated with the other hinds. Four out of six hinds became pregnant and the calves were born in early June. The results of this study showed that the estrus synchronization technique in Refuge Wildlife Park which is based on natural mating, can be used successfully to control inbreeding easily and give young stags the opportunity to copulate.

In this experiment, the effect of PMSG on the output of estrus synchronization following using norgestomet implant was investigated in river buffaloes. Twenty two cyclic female river buffalos at unknown stages of estrus cycle were selected and received norgestomet implant (Crestar, 3mg norgestomet, Intervet, Holland), with an injection of GnRH at first day of experiment. On day 7 after norgestomet insertion, females were randomly assigned into two groups considering their age and weight and both groups of control and experiment received PG F2α (15mg prostiol, prozolin, intervet, Holland). The animals in treatment group received PMSG (Folligon, 1000IU, IM, intervet, Holland) in addition to PG F2α. The implant was removed on day 9 after insertion in all females. Estrous detection was conducted using teaser bull, from 12 hours after norgestomet removal for 7 days every 4 hours for at least 30minutes. From the beginning of sfrous until ovulation, ultrasonography was conducted at the time of estrus, 24, 32 and 40 hours after standing estrus. PMSG had no effect on the frequency of estrous response (Treatment: 100%; control: 81.8%), tightness of estrus synchrony within 12 hours (Treatment: 77/8%; Control: 72/8%) and the frequency of ovulation (Treatment: 100%; control: 88.9%; P>0.05). The interval between the end of treatment and the start of estrus in control group (52.5±4.11 hours) was longer than PMSG group (41.8±8.57 hours; P<0.05). In conclusion, PMSG injection, 2 days prior to the termination of 9 days estrus synchronizationprogram could hasten the time of estrous expression in river buffalo. This has to be considered in fixed timed artificial insemination in this species.