Pregnancy rates following timed embryo transfer with fresh or vitrified in vitro produced embryos in lactating dairy cows under heat stress conditions
Pregnancy rates following timed embryo transfer with fresh or vitrified in vitro produced embryos in lactating dairy cows under heat stress conditions
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DOI：
10.1016/s0093-691x(02)00916-0
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发表时间：
2002-07-01
期刊：
影响因子：
2.8
通讯作者：
Hansen, PJ
中科院分区：
文献类型：
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作者：
Al-Katanani, YM;Drost, M;Hansen, PJ
使用体外产生的（IVP）胚胎而不进行发情检测的定时胚胎移植（TET）可用于减少热应激对生育力的不利影响。一项限制是 IVP 胚胎在冷冻保存后存活率较差。本研究的目的是确认与定时人工授精 (TAI) 相比，TET 对热应激期间妊娠率的有益影响，并确定玻璃化冷冻保存是否可以提高热应激条件下转移到奶牛的 IVP 胚胎的存活率。对于玻璃化胚胎 (TET-V)，采用三步预平衡程序来玻璃化优质的第 7 天 IVP 荷斯坦囊胚。对于新鲜IVP胚胎（TET-F），荷斯坦卵母细胞成熟并受精；使用与玻璃化胚胎生产相同的方法将所得胚胎在改良的 KSOM 中培养 7 天。第 7 天将优质囊胚运送到便携式培养箱中的合作乳品厂，非妊娠、哺乳期荷斯坦牛 (n = 155) 接受 GnRH（100 杯，肌肉注射，第 0 天）治疗，7 天后接受前列腺素 F-2α（PGF(2α)，25 毫克，肌肉注射）和 GnRH（100 杯，肌肉注射）在第 9 天治疗。接受 TAI 治疗的奶牛（n = 68）在第二天（第 10 天）用一头公牛的精液进行授精，该精液也用于产生胚胎。其他治疗中的奶牛（TET-F n = 33；TET-V n = 54）在第 17 天（即预期排卵后第 7 天和第二次 GnRH 治疗后第 8 天）接受胚胎。第 10 天和第 17 天根据血浆孕酮浓度对同步做出反应的奶牛比例为 67.7%。 TET-F 处理中所有奶牛在第 45 天的妊娠率高于 TAI 和 TET-V 处理（P < 0.05）（19.0 垂直于 5.0、6.2 +/- 3.6 和 6.5+/-4.1%）。对于对同步做出反应的奶牛，TET-F 的妊娠率也高于其他处理的妊娠率 (P < 0.05) (26.7+/-6.4、5.0+/-4.3. 和 7.4+/-4.7%)。在 TET-F 治疗组中，产奶较多的奶牛的妊娠率低于产奶较少的奶牛（P < 0.05）。总之，新鲜IVP胚胎的ET可以提高热应激条件下的妊娠率，但玻璃化胚胎移植后的妊娠率并不比TAI更好。 (C) 2002 Elsevier Science Inc. 保留所有权利。
Timed embryo transfer (TET) using in vitro produced (IVP) embryos without estrus detection can be used to reduce adverse effects of heat stress on fertility. One limitation is the poor survival of IVP embryos after cryopreservation. Objectives of this study were to confirm beneficial effects of TET on pregnancy rate during heat stress as compared to timed artificial insemination (TAI), and to determine if cryopreservation by vitrification could improve survival of IVP embryos transferred to dairy cattle under heat stress conditions. For vitrified embryos (TET-V), a three-step pre-equilibration procedure was used to vitrify excellent and good quality Day 7 IVP Holstein blastocysts. For fresh IVP embryos (TET-F), Holstein oocytes were matured and fertilized; resultant embryos were cultured in modified KSOM for 7 days using the same method as for production of vitrified embryos. Excellent and good quality blastocysts on Day 7 were transported to the cooperating dairy in a portable incubator, Nonpregnant, lactating Holsteins (n = 155) were treated with GnRH (100 mug, i.m., Day 0), followed 7 days later by prostaglandin F-2alpha (PGF(2alpha), 25 mg, i.m.) and GnRH (100 mug) on Day 9. Cows in the TAI treatment (n = 68) were inseminated the next day (Day 10) with semen from a single bull that also was used to produce embryos. Cows in the other treatments (n = 33 for TET-F; n = 54 for TET-V) received an embryo on Day 17 (i.e. Day 7 after anticipated ovulation and Day 8 after second GnRH treatment). The proportion of cows that responded to synchronization based on plasma progesterone concentrations on Day 10 and Day 17 was 67.7%. Pregnancy rate for all cows on Day 45 was higher (P < 0.05) in the TET-F treatment than for the TAI and TET-V treatments (19.0 perpendicular to 5.0, 6.2 +/- 3.6, and 6.5+/-4.1%). For cows responding to synchronization, pregnancy rate was also higher (P < 0.05) for TET-F than for other treatments (26.7+/-6.4. 5.0+/-4.3. and 7.4+/-4.7%). In the TET-F treatment group, cows producing more milk had lower (P < 0.05) pregnancy rates than cows producing less milk. In conclusion, ET of fresh IVP embryos can improve pregnancy rate under heat stress conditions, but pregnancy rate following transfer of vitrified embryos was no better than that following TAI. (C) 2002 Elsevier Science Inc. All rights reserved.