Gonadorelin increases semen production and does not affect its quality in Leporinus obtusidens

• Published in: Animal reproduction science 2017-10, Vol.185, p.154-160
• Main Authors: Bernardes Júnior, Jurandir Joaquim, Bombardelli, Robie Allan, Nuñer, Alex Pires de Oliveira
• Format: Article
• Language: English
• Subjects: Animals; Artificial reproduction; CASA; Characiformes - physiology; Dose-Response Relationship, Drug; GnRHa; Gonadotropin-Releasing Hormone - administration & dosage; Gonadotropin-Releasing Hormone - pharmacology; Male; Migratory species; Semen - physiology; Semen Analysis; Semen volume; Sperm Motility - drug effects; Spermatozoa - drug effects
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/j.anireprosci.2017.08.015

•Gonadorelin is an effective inducer for Leporinus obtusidens males.•Gonadorelin enhances semen production by increasing total expressible volume.•Sperm quality was similar in gonadorelin-treated, untreated, and CPE-treated fish.•The minimum effective gonadorelin dose for increasing semen volume is 60μgkg−1. Use of carp pituitary extract (CPE) as a hormone inducer for Leporinus obtusidens is cost-prohibitive; moreover, CPE contains unknown concentrations of gonadotropins. We evaluated the efficacy of gonadorelin as a substitute by analyzing its effect on sperm characteristics of L. obtusidens and cost-effectiveness (20, 40, 60, 80, and 100μgkg−1). Untreated and CPE-treated (4mgkg−1) fish were used as negative and positive controls, respectively. Following a single intramuscular dose of hormones, semen was collected at 200°-h. At doses from 60μgkg−1, all fish produced higher milt volume (P0.05) to the positive control (3.52±0.97mLkg−1). Gonadorelin did not affect sperm concentration (P>0.05). The percentage of morphologically normal spermatozoa was >64% in all treatments. The number of spermatozoa with intact membrane (70%–85%) was equal (P>0.05) to that in the controls. Relative to the negative control, gonadorelin did not affect the motility rate (P>0.05). Curvilinear velocity was equal (P>0.05) to that in both controls. The sperm swimming path was linear (0.9) 10s after activation and was not (P>0.05) dose-dependent. Considering the response rate of gonadorelin-induced fish and the similarity of semen quality compared to controls, the lowest effective dose to produce a higher volume of semen in L. obtusidens is 60μgkg−1, and the cost to induce 1kg of L. obtusidens is 14.0% lower than that with CPE.