This study aimed to evaluate the effect of progesterone (P4) device reutilization in long and short protocols for transcervical timed artificial insemination (TAI) in Santa Inês ewes. A total of 275 multiparous lactating ewes were blocked according to body weight (BW, 49.1?±?7.3 means ± SE), body condition score (BCS, 2.9?±?0.4; scale of 1–5), and days postpartum (50?±?8.2 days), and allocated to one of the treatments. The treatments were arranged in a factorial design, in which the factor 1 was the P4 device type (new or a device of 0.3 g of P4 previously used by 11 days), and the factor 2 was the short or long TAI protocol (P4 device remained by 7 or 11 days, respectively). At device removal, all ewes received 300 IU eCG and 6.70 mg of Dinoprost tromethamine. After TAI protocol, ewes remained with ram by 21 days. There was no interaction between factors in any variables. Ewes that received a new P4 device delayed (P?=?0.05) to show estrus compared with ewes receiving a previously used P4 device, but it did not affect pregnancy rate. The long protocol tended to increase pregnancy rate compared with short protocol (33% vs. 24%, respectively; P?=?0.07). However, the pregnancy rate at the end of reproductive period was similar in both groups (about 84%). Thus, the use of long protocols tended to improve reproductive performance, and the reused P4 device did not affect pregnancy rate.
相似文献This study aimed to determine whether reproductive performance of ewes submitted to laparoscopic timed artificial insemination (TAI) would be similar to ante meridiem (AM)/post meridiem (PM) rule and assisted natural mating (NM), and whether GnRH may enhance the pregnancy rate in TAI. In experiment I, 191 non-lactating ewes were synchronized, then TAI was performed either 48 h after progesterone (P4) removal (TAI-48 h) or 12 h after estrus detection (AM/PM); moreover, some ewes were submitted to NM (NM) as control treatment. In experiment II, 247 non-lactating ewes were allocated in five treatments, a control (no-GnRH on protocol) and four treatments arranged in a factorial design 2 × 2. The factors were time and dose of GnRH: ewes that received either 10 μg (TAI-10 μg-36 h) or 25 μg of GnRH (TAI-25 μg-36 h) 36 h after P4 removal and ewes that received either 10 μg (TAI-10 μg-48 h) or 25 μg of GnRH (TAI-25 μg-48 h) at time of insemination, 48 h after P4 removal. In experiment I, pregnancy rate in TAI-48 h was lower (P = 0.03) than AM/PM and NM. Moreover, the probability of pregnancy in TAI-48 h was higher (P = 0.06) in ewes detected in estrus early. In experiment II, the use of GnRH in TAI protocols increased (P < 0.01) pregnancy rate at synchronization, and TAI-25 μ-48 h and TAI-10 μg-36 h treatments increased (P = 0.02) pregnancy rate compered to TAI-10 μg-48 h. We conclude that TAI decreased pregnancy rate compered to NM and AM/PM, which may be improved by GnRH use in TAI to synchronize ovulation.
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