189 Effect of the number of viable oocytes retrieved from Gyr donor cows on the efficiency of in vitro embryo production in a large-scale commercial program

H. J. Hernandez-Fonseca; A. M. Cambraia Esteves; J. L. Lobo Alves Correia; C. Nogueira; J. Atilio Aranguren-Mendez; J. M. Rodriguez; F. P. Perea

doi:10.1071/RDv36n2Ab189

RESEARCH ARTICLE

189 Effect of the number of viable oocytes retrieved from Gyr donor cows on the efficiency of in vitro embryo production in a large-scale commercial program

H. J. Hernandez-Fonseca ^A , A. M. Cambraia Esteves ^B , J. L. Lobo Alves Correia ^B , C. Nogueira ^C , J. Atilio Aranguren-Mendez ^D , J. M. Rodriguez ^D and F. P. Perea ^E

+ Author Affiliations

- Author Affiliations

^A Department of Anatomy, Physiology and Pharmacology, School of Veterinary Medicine. St. George’s University, St. George’s, Grenada, West Indies

^B BH Embriões, Belo Horizonte, Minas Gerais, Brazil

^C Apoyar Biotech Ltd., Lagoa Santa, Minas Gerais, Brazil

^D Facultad de Ciencias Veterinarias, Universidad del Zulia, Maracaibo, Estado Zulia, Venezuela

^E Facultad de Ciencias Agropecuarias, Universidad de Cuenca, Cuenca, Provincia del Azuay, Ecuador

Reproduction, Fertility and Development 36(2) 249 https://doi.org/10.1071/RDv36n2Ab189

This retrospective study (January 2020–December 2022) aimed to assess the influence of the number of viable oocytes retrieved from donor cows on the efficiency of in vitro embryo production (IVEP). Oocytes were collected by ovum pickup (OPU) without previous hormonal stimulation from 1006 Gyr donor cows independent of their age in 54 commercial farms in the state of Minas Gerais, Brazil. Since this dataset was taken from the records of a commercial IVF company, no information on the age and parity of the donors is available. A total of 53 829 viable oocytes were collected in a total of 3776 OPU sessions. In vitro Gyr × Holstein embryos were produced in a commercial laboratory, following protocols for such purposes. The average number of viable oocytes/OPU obtained from donors was used to divide the donors into quartile groups: Q1: 1–6.9 viable oocytes/OPU; Q2: 7–10.9 viable oocytes/OPU; Q3: 11–17.9 viable oocytes/OPU; and Q4: >18 viable oocytes/OPU. The data were analysed by analysis of variance of SAS. There was a significant difference (P < 0.001) among groups in terms of the number of viable oocytes and cleaved embryos (Table 1). Even though the group with the greatest number of viable oocytes (Q4) yielded the greatest number of blastocysts (P < 0.001), this difference was not detected among the other groups (Q1, Q2, and Q3), although groups Q2 and Q3 showed higher number of oocytes and cleavage embryos than Q1. In this study, the average number of embryos was similar to results presented elsewhere; nonetheless, these studies used the total number of recovered oocytes/OPU instead of the number of viable oocytes/OPU. In conclusion, cows yielding a greater number of viable oocytes showed more cleaved embryos. Nonetheless, a greater number of oocytes only resulted in a greater number of transferable Day-7 blastocysts in the Q4 donor group. The efficiency of the IVEP was significantly decreased as the number of oocytes increased.

Table 1.Number of viable oocytes, cleaved embryos, and viable embryos obtained from Gyr donors submitted to OPU-IVEP (mean ± s.e.m.)

Group	No. of donors	Viable oocytes/OPU	Cleaved embryos/OPU	Blastocysts/OPU	Blastocysts/viable oocyte × 100
Q1	251	5.8 ± 0.45^d	4.42 ± 0.41^d	2.80 ± 0.21^b	48.0 ± 3.26^a
Q2	255	8.9 ± 0.41^c	7.94 ± 0.43^c	3.08 ± 0.20^b	34.5 ± 3.30^b
Q3	264	14.0 ± 0.40^b	11.56 ± 0.41^b	3.27 ± 0.20^b	23.3 ± 2.37^c
Q4	236	28.2 ± 0.43^a	20.82 ± 0.43^a	5.45 ± 0.21^a	19.3 ± 2.30^c

Different letters in the same column differ: ^a–dP < 0.001.