Abstract
•GnRH and eCG were given post-insemination to improve fertility and reduce embryo loss in Harri ewes raised under harsh environmental conditions.•Post-insemination treatment with eCG improved pregnancy rates compared to GnRH treatment.•Luteal function not numbers and circulating concentrations of serum progesterone were increased during pregnancy after eCG treatment.
The objective of the present study was to investigate the effects of post-mating treatments with gonadotropin-releasing hormone analogue (buserelin, GnRH) and equine chorionic gonadotropin (eCG) on ovarian functions, serum progesterone and pregnancy rates in Harri ewes. Ewes (n=58) were treated with 4μg buserelin (GnRH, n=30) and 500 IU eCG (eCG, n=28) 10 days post-mating. The eCG ewes had more CLs (57.1%) than GnRH ewes (33.3%) but diameters of new CLs were not different. The eCG ewes had more (P<0.01) serum P4 concentrations (8.1±0.79ng/ml) than the GnRH ewes (3.9±1.02ng/ml) at day 30 (during pregnancy). Similar trend was recorded at day 60 where serum P4 (8.5±0.79ng/ml) remained elevated (P<0.05) in the eCG compared to the GnRH ewes (6.0±0.79ng/ml) but not at day 90. Ewes treated with eCG had higher (P<0.05) pregnancy rate (46.43%, 13/28) than GnRH-treated ewes (20%, 6/30) at day 30. At day 60, there was a tendency (P=0.07) for the eCG ewes to have higher pregnancy rate (60.7%, 17/28) compared to GnRH ewes (36.7%, 11/30). Post-mating treatments with eCG improved the luteal functions and pregnancy rates compared to GnRH in Harri ewes raised under harsh climatic conditions in tropical regions.