1054 Emir. J. Food Agric ● Vol 34 ● Issue 12 ● 2022 Effect of rams’ social hierarchy upon scrotal circumference, semen quality, and copulation performance under arid land conditions Francisco Gerardo Véliz-Deras 1 , Andrea González-Tavizón 1 , César Alberto Meza-Herrera 2 , Gerardo Arellano-Rodríguez 1 , Miguel Mellado 1 , Oscar Ángel-García 1 , José Ramón Arévalo 3 , Viridiana Contreras-Villarreal 1 * 1 Unidad Laguna, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera, a Santa Fe, Torreón 27054, Coahuila, México, 2 Unidad Regional Universitaria de Zonas Áridas, Universidad Autónoma Chapingo, Bermejillo, Durango 35230, México, 3 Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Universidad de La Laguna, La Laguna, 38206, Tenerife, Spain INTRODUCTION Various sensory systems, such as chemical, visual, auditory, postural, or a combination of these cues, have evolved among animal species to communicate and define social and sexual rank among animals (Fernald and Maruska, 2012; Fox et al. 2019). Regarding social dominance, animals exert such behavior to establish intrasexual competition for mates. In arid zones, the amount of feed resources tend to be limited and must be shared in some way among all members of the flock (Fernald and Maruska, 2012, Broom, 2002). Social rank is established through contests; such hierarchy is positively correlated with body size and body weight (Fernald and Maruska, 2012; Pelletier and Festa-Bianchet, 2006; Orihuela, 2014; Zuñiga-Garcia et al., 2020a, 2020b). These diverse social hierarchies occur among different animal species and production systems, based on the animal´s dominance- aggressiveness levels aligned with the level of subordination of others, which generates heterogeneous reproductive outcomes (Zuñiga-Garcia et al., 2020a, 2020b; Ceacero et al., 2012; Pelletier and Festa-Bianchet, 2006). Indeed, the greater sexual behaviors (DeYoung et al., 2006; Perkins and Fitzgerald, 1994) and reproductive outcomes (Ungerfeld and Lacuesta, 2010) are positively associated with higher- sexually ranked animals. Moreover, chemical cues such as odor (Boehm et al., 2005; Russell and Fernald, 2014), which emanate from the head, neck, and shoulders of males in a testosterone-dependent fashion (Keller and Levy, 2012), modulate reproduction by altering both physiology and behavior of receptive females (Petrulis, 2013). Social hierarchies among animal species are based on the animal´s dominance-aggressiveness level aligned with the subordination of their mates. Social order is mostly defined by animal size, live weight, or age. This study aimed to evaluate the association between odor score (OS), horn presence (HP), horn size (HS), and body temperature on social rank hierarchy, scrotal circumference (SC), semen quality (SQ), and sexual drive (SD). Adult Dorper rams (n=24) with similar live weight (LW), body condition score (BCS), and age (AG) were subjected to a behavioral test to define a success index (SI) based on male-to-male interactions. OS was highest (P<0.05) for rams with high social rank (HSR; 2.5±0.4) and lowest for rams with low social status (LSR; 0.75±0.01). Scrotal circumference was highest (P<0.05) for HSR rams (40.0±3.5) and lowest for rams with medium social rank (MSR; 29.3±1.20). Sperm cell concentration/mL was highest (P<0.05) for HSR rams (3848±187) and lowest for LSR (2660±463). 80% of the HSR rams had horns, while 33.3 of the LSR rams were hornless. The percentage of rejection to mount an estrous ewe was 77.7 for LSR and 20% for HSR and MSR rams (P <0.05). To conclude, the HSR rams presented the highest successful copulation, scrotal circumference, and sperm cell concentration compared to rams with lesser social rank scores. Keywords: Horn presence; Seasonal reproduction; Sexual behavior; Sexual odor; Socio-sexual cues Emirates Journal of Food and Agriculture. 2022. 34(12): 1054-1060 doi: 10.9755/ejfa.2022.v34.i12.2962 http://www.ejfa.me/ ABSTRACT *Corresponding authors: Viridiana Contreras-Villarreal, Unidad Laguna, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera, a Santa Fe, Torreón 27054, Coahuila, México, E-mail: dra.viridianac@gmail.com Received: 01 February 2022; Accepted: 22 November 2022 RESEARCH ARTICLE