ISSN 2449-8955 European Journal of Biological Research Research Article European Journal of Biological Research 2020; 10(3): 240-250 DOI: http://dx.doi.org/10.5281/zenodo.3969026 High level dietary inclusion of monosodium glutamate lowers daily sperm production and efficiency in cocks Olumuyiwa Joseph Olarotimi 1,2 *, Olufemi Adesanya Adu 2 , Abosede Oluwakemi Olarotimi 3 1 Animal Physiology Unit, Department of Animal Science, Faculty of Agriculture, Adekunle Ajasin University, P.M.B 001, Akungba-Akoko, Nigeria 2 Animal Physiology Laboratory, Department of Animal Production and Health, School of Agriculture and Agricultural Technology, The Federal University of Technology Akure, P.M.B. 704, Akure, Nigeria 3 Chemistry Laboratory, Department of Research and Development, Engineering Materials Development Institute (EMDI), KM 4, P.M.B. 611, Akure, Nigeria *Correspondence: Phone: +234 803 565 0055; E-mail: olarotimioj@futa.edu.ng Received: 14 May 2020; Revised submission: 12 July 2020; Accepted: 31 July 2020 http://www.journals.tmkarpinski.com/index.php/ejbr Copyright: © The Author(s) 2020. Licensee Joanna Bródka, Poland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/) ABSTRACT: In a 16-week feeding trial, an investigation was carried out with 240 sexually matured cocks of twenty 24 weeks of age to assess the daily sperm production (DSP) and sperm production efficiency (SPE) of cocks fed dietary monosodium glutamate (MSG) at varied inclusion levels (0.00, 0.25, 0.50, 0.75, 1.00 and 1.25 g/kg diet designated diets A, B, C, D, E and F, respectively). The cocks were weighed (1888.33 ± 44.10 kg) and allotted to the 6 treatment diets. Each treatment was replicated 5 times with 8 cocks/ replicate in a completely randomized design. At the end of the feeding trial, 2 cocks per replicate (i.e. 4 cocks per treatment) were humanely sacrificed and their reproductive tracts dissected. The testes were carefully sampled, weighed and processed for estimation of DSP and SPE using both histological and homogenate methods of analyses. Results showed that the inclusion of MSG at 1.25 g/kg significantly reduced the DSP under the two estimation methods (P<0.05). The SPE was equally significantly lowered at 0.75 g MSG/kg diet and above when determined using the homogenate method. It was also observed that MSG at 1.00 g/kg diet and above lowered the DSP and SPE when determined histometrically. A high positive correlation was established between the DSP and the testicular volume of the cocks. However, the paired testicular sperm reserves were not significantly influenced (P≥0.05). Sperm reserves in both testicles of the cocks fed diets B and C were similar to the control. This study therefore, suggests that MSG has a potential to significantly reduce the reproductive potentials of cocks when administered in excess of 0.75 g/kg diet. Keywords: Cocks; Monosodium glutamate; Sperm production; Testes. 1. INTRODUCTION Feed additives are included in diets for the purpose of enhancing palatability and providing enhanced digestibility of the feed materials to achieve improved performance such as weight gain (WG), increased laying performance, enhancing the sperm production capacity for breeding purposes, improved hatchability and prevention of diseases [1]. Monosodium glutamate (MSG) is reputable for enhanced food palatability, and