Abstract
ABSTRACT In this study, the in vitro production of bovine embryos from zebu and taurine donors was compared. Cumulus-oocyte complexes (COCs) were obtained from 167 Bos taurus and 161 Bos indicus donors by ovum pick-up. COCs were classified based on their morphological quality, matured in incubators for 22 to 24 h in maturation medium, and then fertilized for 18 to 22 h. The zygotes were transferred to the culture medium for seven days. The embryos were classified as morula (OM), initial blastocyst (BI), blastocyst (BL), and expanded blastocyst (BX), before being transferred to synchronized recipient cows. Pregnancy was diagnosed 30-45 days post-transfer. The Bos indicus donors had a higher oocyte yield (n = 2556) than Bos taurus donors (n = 1903) (P = 0.008). The COCs from zebu donors had a better morphological quality than those from taurine donors (n = 689 vs. 444 for grade 1 COC, P < 0.0001; n = 681 vs. 509 for grade 2 COC, P = 0.010, for zebu and taurine donors, respectively). There were differences in embryo production percentages obtained from OM (0.44% from zebu and 6.42% from taurine, P = 0.017), BL (14.18% from zebu and 3.74% from taurine, P < 0.0001), and BX (81.43% from zebu and 75.13% from taurine, P < 0.0001). No significant difference was observed for embryo production from BI and pregnancy rate (P > 0.05). The Bos indicus cows showed greater oocyte recovery, number of viable oocytes, and production of viable embryos than the Bos taurus cows.
Highlights
In the search for the means to improve and increase livestock productivity, the development and use of animal reproductive biotechniques have been considered indispensable (BARUSELLI et al, 2019a)
This biotechnique still continues to present some limitations due to the wide diversity of factors influencing the final results of in vitro production of embryos (IVPE), among which factors related to donors and recipients may be highlighted (MELLO et al, 2016)
It is important that knowledge of the idiosyncrasies of the reproductive physiology of zebu and taurine cows is applied for the optimal implementation of such biotechniques (BATISTA et al, 2020)
Summary
In the search for the means to improve and increase livestock productivity, the development and use of animal reproductive biotechniques have been considered indispensable (BARUSELLI et al, 2019a). The prime goal of IVPE is to produce a greater number of descendants per female donor, since with this technique, it is possible to obtain up to one calf per week per donor, which makes it possible to greatly increase the length of the useful life of breeding cows (MELLO et al, 2016). This biotechnique still continues to present some limitations due to the wide diversity of factors influencing the final results of IVPE, among which factors related to donors and recipients may be highlighted (MELLO et al, 2016). The goal of the present study was to evaluate and compare the in vitro production of bovine embryos from zebu and taurine donors
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