197 Summer affects Holstein cow oocyte recovery but not in vitro embryo development after fertilisation with Gir female sex-sorted semen in tropical environment
M. N. Ribeiro B , L. d. R. Carvalheira A B , N. R. V. Costa B , Á. A. R. FreitasÁ B , A. G. Costa B , M. P. M. Lopes B and R. R. Wenceslau CA Cenatte Embriões, Minas Gerais, Brazil
B Centro Universitário UNA, Curso de Medicina Veterinária, UNA Unidade Linha Verde, Vila Cloris, Belo Horizonte, Minas Gerais, Brazil
C Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
Reproduction, Fertility and Development 35(2) 226-227 https://doi.org/10.1071/RDv35n2Ab197
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
In the present study, we evaluated the effect of season on oocyte recovery for Holstein cows (Bos taurus taurus) and the in vitro embryo production after IVF with Gir (Bos taurus indicus) bull sire female sex-sorted semen to produce Girolando blastocysts. An embryo production database of the year 2020 from Cenatte Embriões IVF company, Brazil, was analysed. The date of OPU was categorised into four seasons: summer (Su [Jan 1–Mar 19; Dec 21–Dec 31]), autumn (Au [Mar 20–Jun 19]), winter (Wi [Jun 20–Sep 21]) and spring (Sp Sep 22–Dec 20]). Data of total oocyte and viable oocytes recovered, the number of presumptive zygotes that cleaved, and the number of grade I blastocysts produced per OPU were evaluated by Poisson mixed regression model in R 4.2.1 software. The model included the fixed effect of season and the random effects of date of OPU, farm, oocyte search technician, donor, and bull sire (the last one just for embryo development data). The Su category was considered the intercept for data comparisons. Data are presented in estimated marginal means and standard error (EMM ± s.e.). The overall database contained data of 54 Holstein donors and 15 Gir bull sires in 120 OPU (total: Su: 11; Au: 38; Wi: 46; Sp: 25), with 2,039 total oocytes (total: Su: 192; Au: 420; Wi: 1,021; Sp: 406) and 1,094 viable oocytes recovered (total: Su: 93; Au: 205; Wi: 604; Sp: 192), and 254 grade I blastocysts produced (total: Su: 31; Au: 41; Wi: 100; Sp: 82). The number of total oocytes recovered in winter were 1.67 times the number in summer (EMM ± s.e.: Su: 10.51 ± 1.65; Au: 9.55 ± 1.34; Wi: 17.54 ± 2.13; Sp: 9.83 ± 1.36; P < 0.001). The number of viable oocytes recovered in winter were 2.11 times the number in summer (EMM ± s.e.: Su: 4.91 ± 1.13; Au: 4.16 ± 0.83; Wi: 10.4 ± 1.8; Sp: 4.3 ± 0.86; P < 0.001). The number of presumptive zygotes that cleaved per OPU in winter, autumn, and spring were similar to the number in summer (EMM ± s.e.: Su: 4.76 ± 1.21; Au: 3.18 ± 0.72; Wi: 5.46 ± 1.12; Sp: 3.32 ± 0.77; P > 0.05). The number of produce grade I blastocyst in autumn was 0.52 times the number in summer (EMM ± s.e.: Su: 1.56 ± 0.42; Au: 0.82 ± 0.18; Wi: 1.61 ± 0.3; Sp: 2.23 ± 0.5; P = 0.01). In conclusion, a greater number of oocytes per OPU from Holstein donors are recovered in winter than in summer. However, there are no differences in the number of produced embryos between these seasons when fertilisation is performed with Gir sire female sex-sorted semen.
The authors thank Cenatte embriões for making the database available for this trial and Centro Universitário UNA - Ânima group for undergradute scholarship.
