Effects of a GnRH administration on testosterone profile, libido and semen parameters of dromedary camel bulls

The optimization of the semen collection procedure and the extension of the breeding season are important issues for improve camel reproductive management. GnRH treatment has been suggested to increase male libido in many species, but achieved results are still conflicting in dromedary camels. The aim of this work was to investigate the effect of a single GnRH analogue dose (100 μg of gonadorelin, Fertagyl®) on testosterone level, behavioral and semen parameters. The same camel bulls (n=5) were used as control (C) and experimental (E) group, and the GnRH was administered trice every 48 hours. Blood samples were collected by catheter every 20 minutes, from 2 p.m. to 6 p.m. (T0 - T12) and semen collection procedures started soon after sampling. GnRH did not affect the testosterone basal level (T0, C vs E: 3.0±0.8 vs 3.5±0.9 ng/ml; P=0.94) and no effect of the repetition, was assessed (P=0.41). Testosterone level showed an upward trend only in treated animals, became statistically significant after 1 hour (T3, C vs E: 2.7±0.7 vs 8.8±2.6 ng/ml; P=0.02), peaking after 140 minutes (T7, C vs E: 2.8±1.8 vs 11.9±3.8 ng/ml; P=0.007), and then slowly decreasing (T12: C vs E: 3.6±1.1 vs 8.7±1.6 ng/ml; P=0.02). During the semen collection procedures the bulls showed a tendency increase in libido, reporting a significant rise in sperm concentration (C vs E: 1085.18±139.6 vs 491.26±139.6 106/ml; P=0.02). From our data, the tested GnRH therapy may be suggested to enhance dromedary male’s libido and probably the optimal time window to collected semen should be between 2 and 3 hours after its administration. So, GnRH effects on behavioral and seminal parameters need to be ascertained with further investigations during more appropriate timing