R.F. Veerkamp and Y. de Haas (eds) Proceedings of 12 th World Congress on Genetics Applied to Livestock Production (WCGALP) 2605 DOI: 10.3920/978-90-8686-940-4_630, © V.M. Del Real-García et al. 2022 630. Allelic diversity and eﬀect of the intronic TBX20-191081 marker on temperament in beef cattle V.M. Del Real-García 1 , A.M. Sifuentes-Rincón 2* , F.A. Paredes-Sánchez 3 , G. Ruíz-de la Cruz 2 , E. Garza-Brenner 1 , G.M. Parra-Bracamonte 2 , H. Bernal-Barragán 1 and F.A. Rodríguez-Almeida 4 1 Facultad de Agronomía, Universidad Autónoma de Nuevo León, 66050 General Escobedo, Nuevo León, México; 2 Centro de Biotecnología Genómica, Instituto Politécnico Nacional, 88710 Reynosa, Tamaulipas, México; 3 Unidad Académica Multidisciplinaria Mante, Universidad Autónoma de Tamaulipas, 89840 El Mante, Tamaulipas, México; 4 Facultad de Zootecnia y Ecología, Universidad Autónoma de Chihuahua, 31453 Chihuahua, Chihuahua, México; asifuentes@ipn.mx Abstract Temperament in cattle is deﬁned as the behavioural response of animals to human handling. Its expression is inﬂuenced by environmental and genetic factors. TBX20 is a candidate gene associated with bovine temperament. e objective was to determine the genetic variability of TBX20-191081 in three cattle beef breeds and evaluate its eﬀect on temperament traits. e allelic frequencies conﬁrmed both alleles segregation in the studied breeds and a signiﬁcant allelic substitution eﬀect for the G allele was observed, which decreases exit velocity (EV) and temperament score (TS). us, its association with docility of beef cattle is evident and genotyping for the marker early in life (e.g. neonates) may allow more ﬂexibility in breeding and selection strategies. Introduction Cattle farming is one of the most developed and practiced livestock activities in Mexico. More than 50% of the national land is used to raise around 32 million head of cattle (SIAP, 2020). Temperament is a complex and economically relevant trait; it reﬂects the well-being of the animal and has been found to be related to productivity traits and job safety (Burdick et al., 2010); it is closely related to gene expression at diﬀerent levels (Cooke et al., 2014). Few studies have explored characteristics of cattle temperament at the genomic level, mainly due to its biological complexity, diﬃculties in the management of animals, and statistical analyses. However, as a result of applying diﬀerent approaches such as the scanning of complete genomes and the use of candidate gene strategy, now it is known that regulation of temperament involves multiple genes with divergent functions. Using genome wide association analyses, we identiﬁed candidate genes with the potential to signiﬁcantly aﬀect temperament in Brahman cattle (Paredes-Sánchez et al., 2019). Among these genes, the marker TBX20-191081 (rs43398069) located within an intron of the T-box transcription factor gene was signiﬁcantly associated with exit velocity, pen score and temperament score, methods commonly used to precisely score cattle temperament (Paredes-Sánchez et al., 2019). is study aimed to estimate the genetic eﬀect and allele frequencies of the genetic marker in three diﬀerent beef cattle breeds: Angus, Brangus and Charolais. Materials & methods Hair samples and temperament records of 89 yearling bulls in a central performance test (35 Angus and 27 Brangus and 27 Charolais cows were included. e data and samples were collected by Garza-Brenner (2017) in the facilities of the Unión Ganadera Regional de Chihuahua (UGRCH), Chihuahua, México and in particular herds located at Nuevo León, Mexico, and kept in the Centro de Biotecnología Genómica- Instituto Politécnico Nacional (CBG-IPN), Reynosa, Tamaulipas, México. ree methods were used to evaluate the animals temperament: (1) pen score (PS), which is a non- restrictive technique, in which the cattle are segregated into small groups (three to ﬁve animals) in a pen https://www.wageningenacademic.com/doi/pdf/10.3920/978-90-8686-940-4_630 - Saturday, February 11, 2023 3:58:57 PM - IP Address:18.232.157.133