Efficacy of embryo transfer in lactating dairy cows during summer using fresh or vitrified embryos produced in vitro with sex-sorted semen

Abstract

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 compa...

Current and Future Assisted Reproductive Technologies for Mammalian Farm Animals

“…As shown in Fig. 1.4 , there is a clear fertility-promoting effect of embryo transfer when fertility is low, as during periods of heat stress (Block et al 2010 ;Stewart et al 2011 ;Vasconcelos et al 2011 ) and in repeat breeder cows (i.e., greater than 2-3 previous unsuccessful inseminations) (Son et al 2007 ;Block et al 2010 ;Canu et al 2010 ). In the absence of low fertility, results have been inconsistent with no improvement in fertility as compared to AI in two studies (Sartori et al 2006 ;Rasmussen et al 2013 ) whereas, in others, pregnancy rates following ET were higher than following AI (Demetrio et al 2007 ;Vasconcelos et al 2006Vasconcelos et al , 2011.…”

Downregulation of gene expression and activity of GRIM-19 affects mouse oocyte viability, maturation, embryo development and implantation

“…The maturity of oocytes was evaluated after 14 h culture. In-vitro matured oocytes (MII) were inseminated by ICSI using mice spermatozoa collected from the cauda epididymidis of KM males (>12 weeks) and purified as described elsewhere [23]. After injection, oocytes were cultured individually in 50-μL droplets of embryo culture medium (G-1, Vitrolife, Sweden) at 37°C under 5 % CO 2 .…”

Postnatal consequences of assisted reproductive technologies in cattle

“…One consequence of embryo production in vitro is that pregnancy rates are often lower than for MOET (Pontes et al, 2009;Siqueira et al, 2009). Moreover, pregnancy failure for pregnancies established following transfer of an IVP embryo can be elevated (Stewart et al, 2011) although this is not always seen (Pereira et al, 2016). Calves derived from IVP embryos have also been reported to experience increased neonatal mortality (van Wagtendonk-de Leeuw et al, 1998;Bonilla et al, 2014).…”

“…Shown are examples of studies in lactating dairy cows in which pregnancy rates were improved by embryo transfer (open bar) as compared to artificial insemination (filled bar). Data from heat stress experiments are from Block et al (2010;Florida), Stewart et al (2011;Texas) and Vasconcelos et al (2011;Brazil). Data from repeat breeder studies are from Son et al (2007;South Korea), Block et al (2010;Florida) and Canu et al (2010;UK).…”