GnRH or estradiol benzoate combination with CIDR improves embryo production in bovines ( and ) under subtropics.

Multiple Ovulation and Embryo Transfer (MOET) technology is a potential technique to upgrade livestock species' genetics. The varied response to super-stimulatory treatments remains one of the limiting factors to this technology's widespread use. The present study was aimed to improve the superovulation response and embryo production by using controlled internal drug release (CIDR)-GnRH or CIDR-EB (Estradiol Benzoate) along with conventional superovulation protocol in Holstein Frisian (HF):  = 42) and Crossbred (XB: Cholistani () × HF;  = 28) cows. In the CIDR-GnRH/CIDR-EB treatment, CIDR was implanted in the cows after confirming the presence of a corpus luteum (CL) on the 8th day after estrus. 2 ml GnRH (Lecirelin acetate 0.0262 mg/ml) or 2 mg EB was also administered in CIDR-GnRH/CIDR-EB groups, respectively. Both groups were given super-stimulatory treatment from the 11th day after estrus (FSH in tapering doses twice a day for four consecutive days). On day 13, two doses of 2 ml prostaglandin (75 µg/ml of dextrorotatory cloprostenol) were administered (am: pm), and CIDR was removed the following day. Two artificial inseminations (AI) of the cows were performed (12 h apart) on the 15th day. No CIDR and GnRH/E.B were given in the control group, but the remaining superovulation protocol was the same. Later on, seven days after the first AI, non-surgical embryo flushing was done. The transferable embryos produced from three different superovulation protocols were then transferred into the recipient cows ( = 90) for determining their fertility. Statistical analysis revealed that the number of super-estrus follicles (SEF), multiple corpora lutea (MCL), ovulation/fertilization percentage, fertilized structures recovered (FSR), and transferable embryos (TEs) remained significantly higher ( < 0.05), and days taken for return to estrus (RTE) after embryo collection remained significantly lower ( < 0.05) in CIDR-GnRH ( = 18) and CIDR-EB ( = 15) groups as compared to the control ( = 37). The comparison between XB and HF cows revealed that the TEs production in CIDR-GnRH (XB = 5 HF = 13) and CIDR-EB (XB = 6  HF = 9) based superovulation protocols were 11.60  ±  4.08  04.31  ±  0.98 and 09.33  ±  1.78  05.22  ±  1.36, respectively. TEs production in XB cows ( = 5) of the CIDR-GnRH group was significantly higher (11.60  ±  4.08) than other groups. On the other hand, the days taken for RTE after embryo collection remained significantly lower ( < 0.05) in HF cows of treatment groups. However, the fertility of TEs was neither affected significantly ( > 0.05) by the superovulation protocol used nor by breed differences among donor cows. In conclusion, using CIDR-GnRH or CIDR-EB along with conventional superovulation protocol may enhance the efficiency of MOET programs in cattle. Furthermore, XB donor cows demonstrated a better performance than HF donor cows under subtropical conditions.