Contents lists available at ScienceDirect Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci Effects of vulvar width and antral follicle count on oocyte quality, in vitro embryo production and pregnancy rate in Bos taurus taurus and Bos taurus indicus cows Gisvani Lopes de Vasconcelos a , Ellen Vasconcelos da Cunha b , Renata Maculan a , Jesús Alfonso Sánchez Viafara a , Anderson Weiny Barbalho Silva b , Ana Liza Souza Batista b , José Roberto Viana Silva b , José Camisão de Souza a, * a Animal Science Department, Federal University of Lavras, Lavras, MG, Brazil b Laboratory of Biotecnology and Physiology of Reproduction – LABIREP, Federal University of Ceara, Sobral, CE, Brazil ARTICLE INFO Keywords: Antral follicle count Vulvar width Oocyte quality Embryo production ABSTRACT It was hypothesized that Brahman cows have greater in vitro embryo production than Simmental cows, and that regardless of breed, antral follicle count (AFC) and vulvar width (VW) are posi- tively associated with oocyte quality, embryo number and pregnancy rate. Brahman (Bos taurus indicus, n = 184) and Simmental (Bos taurus taurus, n = 99) cows were classified as having a large AFC (Brahman: ≥50, Simmental: ≥25); intermediate AFC (Brahman: > 30 and ≤49; Simmental: > 16 and < 24) and small AFC (Brahman: < 30, Simmental: ≤15). The VW was considered to be large (Brahman: > 123 mm, Simmental: > 80 mm); intermediate (Brahman: > 102 mm and ≤123 mm; Simmental: > 65 mm and ≤80 mm) and small (Brahman: ≤102 mm and Simmental: ≤65 mm). For each group of cows, ovum pick up, oocyte in vitro maturation, fertilization and embryo culture were performed. Embryo transfers were subse- quently performed and pregnancy rate was evaluated. Brahman cows had a larger number of viable oocytes, greater efficiency of embryo production and greater pregnancy rate (P < 0.05) than Simmental cows. Pregnancy percentages in Simmental cows with a small AFC were greater than those cows with an intermediate and large AFC. With the Brahman cows, there was no difference in pregnancy rate among the cows with different AFC classifications. In contrast to Simmental cows, Brahman cows with an intermediate VW had a greater pregnancy percentage than those with a small and large AFC. In conclusion, Brahman cows have a larger AFC, number of viable oocytes, and pregnancy rate than Simmental cows. 1. Introduction In vitro embryo production (IVP) is one of the most important assisted reproduction technologies in cattle breeding and, in the last decades, many efforts have been made to improve efficacy when using IVP procedures. Only 35%–40% of in vitro matured oocytes develop to the blastocyst stage after in vitro fertilization and embryo culture (Sirard et al., 2006) and about 30 % of these embryos are of a quality worthy of transfer into recipients (Park et al., 2005). One of the factors that contribute to this lesser than optimal efficiency of IVP is the removal of the oocyte from its natural environment, and the effects of the culture conditions, media https://doi.org/10.1016/j.anireprosci.2020.106357 Received 10 September 2019; Received in revised form 17 March 2020; Accepted 18 March 2020 ⁎ Corresponding author at: Departamento de Zootecnia, Universidade Federal de Lavras, Lavras, MG, Campus da UFLA, 37200-000, Brazil. E-mail address: jcamisao@ufla.br (J.C. de Souza). Animal Reproduction Science 217 (2020) 106357 Available online 27 April 2020 0378-4320/ © 2020 Elsevier B.V. All rights reserved. T