Twelve rams and forty-eight ewes (½ Finland x ½ Rahmani) were used to study
the possibility of using GnRH or Melatonin to improve the reproductive efficiency
under hot summer conditions. The animals were divided into three equal and similar
groups. The 1st group of rams was subjected to intramuscularly injection of saline
solution (0.9% NaCI) as a control group. The 2nd group was intramuscularly injected
with GnRH and the 3rd groups received Melatonin orally.
GnRH treatment improved (P<0.05) the heat-stressed rams libido, mating activity,
fertility, serum testosterone, semen-ejaculate volume and total sperm output than in
the control. Meanwhile sperm motility, dead spermatozoa, abnormalities, acrosomal
integrity and sperm cell concentration did not change appreciably as a function of this
treatment.
Treatment heat stressed rams with Melatonin increased (P<0.05) mating activity
and fertility but the other reproductive performance traits did not differ than the
control.