Effect of Gonadotropin Releasing Hormone Treatment on Semen Characteristics and Enzymatic Activities of Awassi Rams in Breeding and Non Breeding Seasons

Abstract

This study was aimed to evaluate the effect of GnRH injection on semen ejaculate characteristics in Awassi rams collected in breeding and non breeding seasons. The study was conducted in late summer to early autumn when breeding activity commences, and in winter during the non breeding season. Twelve mature Awassi rams were used in this study. Animals were randomly allocated into two equal groups, the experimental group received 50 µg IM of GnRH weekly andthe control group received 1 ml of saline. Libido was assessed and semen samples were collected from the Awassi rams 24 hours after IM administration. Scrotal circumference (SC) and testicular volume were measured weekly during the study period. Ejaculates were collected 24 hours after each GnRH/saline administration and assessed for volume, sperm concentration, mass and individual motility, live sperm and sperm abnormalities. Seminal plasma was assayed for the estimation of alanine amino transferase (ALT), aspartate amino transferase (AST), acid phosphatase (ACP), alkaline phosphatase (ALP) and lactic dehydrogenase (LDH). Results show that GnRH treatment improves semen volume, total ejaculated sperm and reaction time in both breeding and non-breeding seasons compared to control (P<0.05). However, GnRH treatment reduces the activity of LDH in both seasons. Other seminal traits show similar values for both seasons. In conclusion, GnRH treatment of Awassi rams improved libido, semen volume, sperm numbers, but not sperm viability.