Single or Double Inseminations at Fixed-Time Basis on Lambing Rate of Ewes Treated with Porgestogen-Impregnated Intravaginal Sponges during the Non-Breeding Season.

et al. 2004

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Abstract. The aim of the present study was to compare three methods of estrus synchronization in ewes during the non-breeding season. Forty-two ewes were randomly grouped for three treatments with different intravaginal devices for 12 days: Group A) CIDR, Group B) Self-made P sponge, Group C) MAP (medroxyprogesterone acetate) cream sponge. Furthermore, all groups were divided into two treatments with (R) or without ram presence to examine the "ram effect". Blood was collected from all treated ewes, and progesterone (P4), estradiol 17-β (E2) and luteinizing hormone (LH) concentrations were measured by enzyme-immnoassay. All ewes showed estrus behavior between Day 0 to 3 after device removal, and the mean onset times of their estrus were 23.0, 33.0 and 21.0 h for Groups AR, BR and CR, respectively. On Day 5 as examined by laparoscopy, the ovulation rates (and number of ovulated ewes) were 1.45 (11/11), 1.25 (12/14) and 1.21 (14/14) for Groups A, B and C, respectively. In Group C, the time to LH surge was significantly (P<0.05) later (32.4 h) than those in Groups A (27.0 h) and B (25.5 h). Ram presence did not affect the number of ovulated ewes, ovulation rate or time to LH surge. The ram introduction group had significantly (P<0.05) lower E2 concentrations during the period from 0 h to 36 h than the groups without ram presence. These results suggest that the self-made P sponge or MAP cream sponge was effective as well as CIDR, and ram introduction was not necessary, for induction of estrus and ovulation during the non-breeding season. Key words: Induction of estrus, Intravaginal device, Non-breeding season, Sheep (J. Reprod. Dev. 50: [63][64][65][66][67][68][69] 2004) strus synchronization is generally applied for reproductive management of sheep flocks worldwide [1], and several methods have been performed with varying degrees of success [2]. The attempted methods are control of daily length and/ o r h o r m o n a l t r e a t m e n t s s u c h a s n a t u r a l p r o g e st e r o n e , s y n t h e t i c p r o g e s t o g e n s ,

Section: Discussionsupporting

confidence: 93%

Section: Treatmentmentioning

confidence: 99%

mentioning

confidence: 99%

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A Comparative Study of Induction of Estrus and Ovulation by Three Different Intravaginal Devices in Ewes during the Non-Breeding Season

Iida

Kobayashi

et al. 2004

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“…Paulenz et al [19,20] reported that the fertility of ewes inseminated by cervical AI with liquid semen was significantly different among farms, but that the ewe age had no significant effect. In our previous AI study [31] using cervical AI with fresh undiluted semen during the non-breeding season, we also found a farm-related difference in the lambing rates of three farms. In one of the three farms, the mean age of the ewes was higher (5.8 ± 1.7 years old, n=88) and the BCS was lower (2.9 ± 0.5) than the ewes in the other two farms (4.4 ± 1.5 and 3.8 ± 1.4 years old for age, and 3.4 ± 0.6 and 3.3 ± 0.5 for BCS).…”

Section: Discussionsupporting

confidence: 52%

Factors Affecting the Fertility of Ewes after Intrauterine Insemination with Frozen-Thawed Semen During the Non-Breeding Season

Fukui

Okabe

et al. 2010

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In this study, two successive field trials were conducted during the non-breeding season to investigate various factors affecting on fertility of Suffolk ewes after intrauterine insemination with frozen-thawed semen. In the first year (Experiment 1), three sperm numbers per insemination dose (0.25, 0.5 and 1 million sperm) and five sheep farms were used, and in the second year (Experiment 2), parity, age, body weight, body condition score (BCS) and postpartum days were investigated to compare pregnancy and lambing rates. High pregnancy and lambing rates (70.6 and 70.6%, respectively) were obtained with 0.25 million sperm per dose. There were no significant differences in the pregnancy and lambing rates among the five farms, but there was a tendency for one farm to have higher pregnancy (75.8%, P=0.065) and lambing (72.7%, P=0.077) rates than those (46.7-53.3% and 45.2-53.3% for the pregnancy and lambing rates, respectively) of the other farms. In Experiment 2, ewe age significantly affected both the pregnancy and lambing rates. Nulliparous ewes had a higher lambing rate (72.0%) than that (44.2%) of multiparous ewes, but a significant difference was not revealed. Regardless of body weight, BCS tended to be an important factor influencing on fertility of ewes. Body weight and the postpartum days did not affect the fertility of ewes. It was concluded from these results that the fertility of Suffolk ewes after intrauterine insemination with frozen semen was significantly influenced by sperm number per dose and ewe age. Nulliparous ewes at less than three years of age and with a BCS of more than 3.0 are expected to have higher fertility than other ewes.

“…However, CIDR-G is not available for sheep production in Japan. To solve this problem, several i n t r a v a g i n a l d e v i c e s i m p r e g n a t e d w i t h progesterone or synthetic progestogen have been examined [7][8][9][10]. Recently, a new method using cream containing 25 mg CAP (chlormadinone acetate progesterone) or 60 mg MAP (intravaginal cream method) has been developed in Japan [11,12].…”

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confidence: 99%

Comparison of Estrus Induction and Subsequent Fertility with Two Different Intravaginal Devices in Ewes during the Non-Breeding Season

Okamoto

Iida

et al. 2005

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Abstract.Two experiments were conducted to compare the effect of estrus induction by controlled internal drug release (CIDR) and intravaginal cream containing 500 mg progesterone (P cream) in ewes during the non-breeding season. In the first experiment, twenty-four ewes were randomly grouped for two treatments with the different intravaginal devices for 12 days: Group A was the CIDR group and Group B was the P cream group. Blood was collected from all treated ewes, and progesterone (P4), estradiol 17-β (E2) and luteinizing hormone (LH) concentrations were measured by enzyme immunoassay. In the second experiment, the conception rates from natural mating, estrusdetected AI (inseminated 12 h after estrus detection), or fixed-time AI (inseminated 42 h after removal of an intravaginal device) in 127 ewes treated with CIDR or P cream were compared. In Experiment 1, the rate of estrus induction and the time of estrus onset after device removal were 91.7% and 36.3 ± 15.7 h in Group A, and 100% and 35.0 ± 12.6 h in Group B, respectively. There were no significant differences between the devices. The mean plasma P4 concentration in Group B was significantly (P<0.01) lower than Group A between day -9 and day -1 (Day 0: the day of device removal). However, no significant differences were found in the mean E2 concentrations of the two groups after treatment. The mean time of estrus onset in ewes with an observed LH surge and the time of LH surge after treatment were 23.3 ± 8.7 h and 30.3 ± 5.0 h for Group A and 27.6 ± 6.5 and 26.3 ± 8.0 h for Group B, respectively, and there were no significant differences. However, a significant difference (P<0.05) was found in the mean time from the time of estrus onset to LH surge between Group A (6.4 ± 6.7 h) and Group B (-1.3 ± 4.1 h). In Experiment 2, the conception rates for natural mating, estrus-detected AI, and fixed-time AI were 55.0, 29.4, and 25.0% for Group A and 40.7, 25.0, and 42.1% for Group B, respectively, and there were no significant differences. These results suggest that the effect of induction of estrus and ovulation and the rate of conception after treatment were comparable to CIDR even though the plasma P4 concentration of the P cream method tended to be low during the insertion period. Key words: Estrus induction, Fertility, Intravaginal device, Non-breeding season, Sheep (J. Reprod. Dev. 51: [805][806][807][808][809][810][811][812] 2005) ethods of estrus induction in ewes using various intravaginal devices impregnated with progesterone or synthetic progestogen have been developed and used throughout the world.The main method is an intravaginal sponge