Texas AgriLife Research and Extension, Texas A&M System, Stephenville, USA.
J Dairy Sci. 2011 Jul;94(7):3437-45. doi: 10.3168/jds.2010-4008.
The objective was to determine whether transfer of fresh or vitrified embryos produced in vitro with sex-sorted semen improves pregnancy and calving rates during summer in lactating dairy cows compared with artificial insemination (AI). Lactating dairy cows (n=722) were enrolled during summer months at 2 commercial dairies in Central Texas and randomly assigned to 1 of 3 treatments: AI with conventional semen (n=227), embryo transfer-vitrified (ET-V; n=279) or embryo transfer-fresh (ET-F; n=216). Embryos were produced in vitro using sex-sorted semen and with Block-Bonilla-Hansen-7 culture medium. For vitrification, grade 1 expanded blastocysts were harvested on d 7 after fertilization and vitrified using the open-pulled straw method. Fresh embryos were grade 1 blastocysts and expanded blastocysts harvested on d 7 after fertilization. Cows were submitted to the Ovsynch56 protocol: d -10 GnRH, d -3 PGF(2α), d -1 GnRH and d 0 timed AI; or Select Synch protocol: d -9 GnRH, d -2 PGF(2α), and AI following detected estrus (day of AI=d 0). On d 7, all cows were examined for presence of a corpus luteum (CL). A vitrified or fresh embryo was transferred to cows with CL in ET-V and ET-F groups. Cows were considered synchronized if progesterone was <1ng/mL on d 0 and a CL was present on d 7. At d 40±7 of gestation, the percentage of cows pregnant was greater for the ET-F compared with the ET-V and AI groups among all cows (42.1 vs. 29.3 and 18.3%, respectively) and synchronized cows (45.5 vs. 31.6 and 24.8%, respectively). Also, the percentage of cows pregnant was greater for the ET-V than the AI group among all cows and tended to be greater among synchronized cows. At d 97±7 of gestation, the percentage of cows pregnant among all cows was greater for ET-F and ET-V groups than for the AI group (36.4 and 25.7 vs. 17.0%, respectively) and the percentage for the ET-F group was greater than for the ET-V group. Among synchronized cows, the percentage of cows pregnant was significantly increased for the ET-F group than for ET-V and AI groups (39.4 vs. 27.8 and 23.1%, respectively) and no difference was found between ET-V and AI groups. No effect of treatment on embryo loss was observed. The percentage of cows with live births was significantly increased for the ET-F than for ET-V and AI groups among all cows (27.5 vs. 17.1 and 14.6%, respectively) and synchronized cows (29.9 vs. 18.5 and 20.0%, respectively). The percentage of cows giving birth to a live heifer was significantly increased for the ET-F and ET-V groups compared with the AI group among all cows (79.1 and 72.5 vs. 50.0%, respectively) and synchronized cows (79.1 and 72.5 vs. 50.0%, respectively). No difference existed between ET-F and ET-V groups for percent live heifer births but both were greater than for the AI group. The transfer of fresh embryos produced in vitro using sex-sorted semen to lactating dairy cows during summer can effectively increase the percentage of cows that establish pregnancy and also the percentage of cows that give birth to a live heifer compared with percentages from AI with conventional semen.
目的是确定在夏季对泌乳奶牛进行体外受精（IVF）并使用性别分选精液进行新鲜或玻璃化胚胎移植是否比人工授精（AI）更能提高妊娠率和产犊率。在德克萨斯州中部的 2 家商业奶牛场的夏季，将 722 头泌乳奶牛纳入研究，并随机分配到 3 种处理组之一：使用常规精液的 AI（n=227）、胚胎移植-玻璃化（ET-V；n=279）或胚胎移植-新鲜（ET-F；n=216）。胚胎是使用性别分选精液和 Block-Bonilla-Hansen-7 培养基在体外产生的。对于玻璃化处理，受精后第 7 天收获等级 1 的扩张囊胚，并使用开放拉制 straw 方法进行玻璃化处理。新鲜胚胎是受精后第 7 天收获的等级 1 囊胚和扩张囊胚。奶牛接受 Ovsynch56 方案：-10 GnRH、-3 PGF(2α)、-1 GnRH 和 d 0 定时 AI；或 Select Synch 方案：-9 GnRH、-2 PGF(2α)，并在发情后（AI 日为 d 0）进行 AI。在第 7 天，所有奶牛都检查黄体（CL）的存在情况。在 ET-V 和 ET-F 组中，有 CL 的奶牛接受冷冻或新鲜胚胎移植。如果奶牛在 d 0 时孕激素<1ng/mL，并且在第 7 天存在 CL，则被认为是同步的。在妊娠第 40±7 天，与 ET-V 和 AI 组相比，所有奶牛中 ET-F 组怀孕的百分比更高（分别为 42.1%、29.3%和 18.3%）和同步奶牛（分别为 45.5%、31.6%和 24.8%）。此外，与 AI 组相比，所有奶牛中 ET-V 组怀孕的百分比更高，且在同步奶牛中趋势更高。在妊娠第 97±7 天，所有奶牛中 ET-F 和 ET-V 组怀孕的百分比高于 AI 组（分别为 36.4%、25.7%和 17.0%），且 ET-F 组的百分比高于 ET-V 组。在同步奶牛中，ET-F 组怀孕的百分比明显高于 ET-V 和 AI 组（分别为 39.4%、27.8%和 23.1%），而 ET-V 和 AI 组之间没有差异。处理对胚胎损失没有影响。与 ET-V 和 AI 组相比，所有奶牛中 ET-F 组的活产牛比例显著增加（分别为 27.5%、17.1%和 14.6%）和同步奶牛（分别为 29.9%、18.5%和 20.0%）。与 AI 组相比，所有奶牛中 ET-F 和 ET-V 组的活产母牛头比例显著增加（分别为 79.1%、72.5%和 50.0%）和同步奶牛（分别为 79.1%、72.5%和 50.0%）。ET-F 和 ET-V 组的活产母牛头比例之间没有差异，但均高于 AI 组。与传统精液 AI 相比，在夏季对泌乳奶牛进行体外受精并使用性别分选精液进行新鲜胚胎移植可以有效地提高奶牛妊娠率和活产母牛头比例。
