198 Seasons affect Gir cow oocyte recovery and in vitro embryo development after fertilisation with Holstein female sex-sorted semen in tropical environment
L. d. R. Carvalheira A B , M. N. Ribeiro 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) 227-227 https://doi.org/10.1071/RDv35n2Ab198
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 from Gir cows (Bos taurus indicus) and the in vitro embryo production after IVF with Holstein (Bos taurus taurus) 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 cleaved embryos, 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, veterinarian, oocyte search technician, donor, and bull sire (the last one just for embryo development data). Data are presented in estimated marginal means and standard error (EMM ± s.e.). The overall database contained data of 3,634 Gir donors and 124 Holstein bull sire in 8,205 OPU (total: Su: 1,373; Au: 2,126; Wi: 2,878; Sp: 1,828), with 167,604 total oocytes (total: Su: 29,354; Au: 43,248; Wi: 58,042; Sp: 36,960), and 95,256 viable oocytes recovered (total: Su: 16,283; Au: 24,222; Wi: 33,509; Sp: 21,242), and 31,871 grade I blastocysts produced (total: Su: 5,668; Au: 7,792; Wi: 11,129; Sp: 7,282). The number of total oocytes recovered per OPU was lower in spring (EMM ± s.e.: Su: 19.5 ± 1.43; Au: 19.7 ± 1.44; Wi: 17.4 ± 1.27; Sp: 13.3 ± 0.96). The number of total oocytes in spring and winter is expected to be, respectively, 0.7 and 0.9 times the number in summer (P < 0.001). The number of viable oocytes recovered per OPU was lower in spring (EMM ± s.e.: Su: 10.45 ± 0.8; Au: 10.48 ± 0.8; Wi: 9.55 ± 0.7; Sp: 7.41 ± 0.56). The number of viable oocytes in spring and winter is expected to be, respectively, 0.71 and 0.91 times the number in summer (P < 0.001). The number of cleavage oocytes per OPU was lower in spring (EMM ± s.e.: Su: 9.25 ± 0.73; Au: 8.64 ± 0.67; Wi: 7.91 ± 0.6; Sp: 6.17 ± 0.47). The number of cleaved oocytes in spring, autumn, and winter is expected to be, respectively, 0.67, 0.93, and 0.85 times the number in summer (P < 0.001). The average number of grade I blastocysts produced per OPU did not differ between seasons (EMM ± s.e.: Su: 2.57 ± 0.25; Au: 2.31 ± 0.22; Wi: 2.34 ± 0.22; Sp: 2.01 ± 0.2). However, the number of produced grade I blastocysts in spring, autumn, and winter are expected to be, respectively, 0.80, 0.90, and 0.91 times the number in summer (P < 0.001). In conclusion, a greater number of oocytes per OPU from Gir donors is expected to be recovered in the summer than in other seasons, as well as more cleaved embryos and grade I blastocysts when fertilisation is performed with Holstein 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.
