Contents lists available at ScienceDirect Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci Ultrasonographic characteristics of the testes, epididymis and accessory sex glands and arterial spectral indices in peri- and post- pubertal Nelore and Caracu bulls Naiara Nantes Rodrigues a, *, Guilherme Fazan Rossi a , Dayane Priscila Vrisman a , Augusto Ryonosuke Taira a , Luana Lelis Souza b , Mariana Furtado Zorzetto b , Natália Marins Bastos a , Claudia Cristina Paro de Paz b , Vera Fernanda Martins Hossepian de Lima a , Fabio Morato Monteiro b , Maria Emilia Franco Oliveira a, * a Faculdade De Ciências Agrárias E Veterinárias, Universidade Estadual Paulista, Via De Acesso Prof. Paulo Donato Castellane, s/n, Cep 14884-900, Jaboticabal, SP, Brazil b Centro APTA Bovinos De Corte, Instituto De Zootecnia, Rodovia Carlos Tonani, Km 94, Cep 14160-900, Sertãozinho, SP, Brazil ARTICLEINFO Keywords: Andrological Bovine Echogenicity Echotexture Vascular indices ABSTRACT Ultrasonography can provide information about the integrity of organs; however, rarely is ap- plied to the reproductive organ evaluation of bulls. The objective of the present study was to characterize and compare values for variables and ultrasonographic characteristics of the testes, epididymis and accessory sex glands, as well as spectral Doppler indices of the testicular and internaliliacarteries,betweenperi-andpost-pubertalNeloreandCaracubulls.Nelore(n =203) and Caracu (n = 79) bulls were assigned by age class: peri-pubertal (12–15 months) and post- pubertal (>22 months). Data were analyzed using SAS’s PROC MIXED procedure (P <0.05). The biometric variables of the testes and cauda epididymis differed between peri- and post- pubertalNeloreandCaracubulls.Therewasadifferencebetweenbreedsforthevesicularglands, ampulla of vas deferens, disseminate portion of the prostate, and craniocaudal dimension of the bulbourethralglands.Echogenicityofthetesticularparenchymadifferedbetweenbreedsandage classes. The pulsatility and resistive indices of the testicular arteries differed between Nelore and Caracu bulls. The biometric and ultrasonographic characteristics of the testes, epididymis and accessory sex glands, as well as of the arterial indices in bulls are affected by genetic group and age class, and when assessed there is useful information regarding the progression of sexual maturation. 1. Introduction The fertility of bulls has a greater effect on the reproductive performance of a herd than that of cows because a single bull mates with a large number of females, with the recommendation in Central Brazil for bull:cow ratio is 1:25 (Sereno et al., 2002). The identification and culling of bulls with relatively lesser fertility, therefore, has great importance because compromised bull fertility can lead to economic losses due to lesser pregnancy rates than when highly fertile bulls are used (Santos et al., 2004). Breeding https://doi.org/10.1016/j.anireprosci.2019.106235 Received 1 May 2019; Received in revised form 22 October 2019; Accepted 15 November 2019 ⁎ Corresponding authors at: Via de Acesso Prof. Paulo Donato Castelane, S/N - Vila Industrial, Jaboticabal, SP, 14884-900, Brazil. E-mail addresses: naiara_nantes@hotmail.com (N.N. Rodrigues), m_emiliafraoli@yahoo.com.br (M.E. Franco Oliveira). Animal Reproduction Science 212 (2020) 106235 Available online 16 November 2019 0378-4320/ © 2019 Elsevier B.V. All rights reserved. T