Research Effect of glutamate and/or testosterone administration on appetitive and consummatory sexual behaviors in pubertal rams and their influence on the reproductive performance of nulliparous anovulatory ewes Guadalupe Calderón-Leyva a, b , Cesar A. Meza-Herrera c, * , Rafael Rodriguez-Martinez a , Oscar Angel-García a , Raymundo Rivas-Muñoz d , Juan V. Delgado-Bermejo b , Francisco G. Véliz-Deras a a Agriculture and Livestock Graduate Program, Antonio Narro Agricultural Autonomous University, Torreon, Mexico b Department of Genetics, University of Cordoba, Cordoba, Spain c Regional Universitary Unit on Arid Lands, Chapingo Autonomous University, Bermejillo, Durango, Mexico d Technology Institute of Torreon, Torreon, Coahuila, México article info Article history: Received 29 April 2018 Received in revised form 2 December 2018 Accepted 10 December 2018 Available online 18 December 2018 Keywords: anestrous season Dorper sheep glutamate testosterone sexual behavior reproductive performance abstract We tested whether glutamate and/or testosterone administration to pubertal Dorper rams would in- crease their apptetitive sexual behavior (ASB) and consummatory sexual behavior (CSB). We then evaluated their ability to induce the sexual response of nulliparous-anestrous ewes during early spring (26 N). Dorper rams (n ¼ 20, 11 months old) were distributed in four groups homogeneous regarding live weight ([LW], 55 0.09 kg), body condition score (3.2 0.1 units), and scrotal circumference (30 0.3 cm) and received the following treatments of: 1) intramuscular glutamate (GG); 7 mg kg 1 LW of glutamate (every 3 days 28 days; iv), 2) testosterone treated (GT); 1 ml of saline (every 3 days 15 days; iv) þ 25 mg of testosterone (every 3 days 15 days; im), 3) glutamate þ testosterone (GGT); 7 mg kg 1 LW of glutamate (every 3 days 28 days; iv) þ 25 mg testosterone (every 3 days 15 days; im), and 4) GC; 1 mL of saline (every 3 days 28 days; iv). Thereafter, nulliparous-anestrus Dorper ewes (n ¼ 80; LW 42.2 2.3 kg, body condition score 3 0.09 units) were exposed to these treated males. On male-to-female contact, a sexual behavioral test (2 hours 2 days) was conducted to evaluate the ASB and CSB frequencies. Afterward, the female reproductive performance (interval to estrus, estrus response, ovulation response, ovulation rate, and pregnancy rate) was quantified. Although the GGT- males had the best ASB and ASBþCSB (P < 0.05), the GT-males had the best CSB (P < 0.05). The estrus response, ovulation response, and ovulation rate did not differ (P < 0.05) among groups, yet, interval to estrus and pregnancy rate favored (P < 0.05) to the ewes-GGT rams. Our results revealed that the ASB and CSB of young Dorper rams were improved by frequent GGT administration. Moreover, the shortest onset to estrus and the largest pregnancy rate were observed in those ewes exposed to the GGT- treated pubertal rams. Such results are encouraging from a comparative sexual behavior standpoint, while may hold potential translational applications. Ó 2018 Elsevier Inc. All rights reserved. Introduction In small ruminants, mainly under temperate and subtropical conditions, a seasonal pattern of reproductive function has been reported, being more accentuated as genotypes originate from northern latitudes (Goodman et al., 2010). Such reproductive behavior generates a defined pattern of ovarian activity with most Conflict of interest: None of the authors have any conflict of interest to declare. * Address for reprint requests and correspondence: Cesar A. Meza-Herrera, Grad- uate Program, UACH-URUZA, Environmental Animal Physiology Galeana 585 Pte. Ciudad Lerdo, Durango, México 35150. Tel: þ52 872 7760160; Fax: þ52 872 7760190. E-mail addresses: cmeza2020@hotmail.com, cmeza2000@gmail.com (C.A. Meza-Herrera). URL: https://www.researchgate.net/profile/meza-herrera Contents lists available at ScienceDirect Journal of Veterinary Behavior journal homepage: www.journalvetbehavior.com https://doi.org/10.1016/j.jveb.2018.12.008 1558-7878/Ó 2018 Elsevier Inc. All rights reserved. Journal of Veterinary Behavior 30 (2019) 96e102