The present study was designed to investigate the impact of exogenous administration of GnRH (Receptal VET®, Intervet Pharmaceuticals Ltd., India) on serum progesterone profile and conception rates during mid luteal phase of estrous cycle in buffaloes. Estrus was induced using Cyclix 2 mL. i/m. (Intervet India Pvt. Ltd., India) and animals were bred naturally during observed estrus. The buffaloes (n=40) were grouped as control (n=10) on day 0 and treatment groups (I, II and III, n=10 in each group). GnRH (2.5 mL) was administrated on day 0, 11 and 13 of estrous cycle. Progesterone concentration was significantly higher (P<0.05; 1.782±0.046 ng/mL) in group I on day 5 and in group II on day 13 (4.514±0.038 ng/mL) and day 18 (6.173±0.015). However, in group III progesterone concentration was significantly higher on day 18 (6.554±0.0993) compared to control on day 5 (1.390±0.587 ng/mL), day 13 (3.770±0.103 ng/mL) and day 18 (5.114±0.009 ng/mL), respectively. Although progesterone concentration increased in all the three treatment groups compared to control, it was significantly higher (P<0.05) in pregnant animals of group I on days 5, 11, 12, 13 and 18 than non-pregnant animals of same group. Nevertheless, these differences were significant on days 13 and 18 in group II and on day 18 in group III in pregnant animals compared to non-pregnant animals, respectively. Similarly the conception rate was also significantly higher (P<0.05; 80% vs. 60%) in animals at group III compared to those at control.Comparison of data on progesterone profile between pregnant and non-pregnant (within group) animals of various treatment and control groups showed significantly higher levels of serum progesterone in pregnant animals on days 11, 12, 13 and 18 as compared tonon-pregnant animals of the same group. Thus, the above study revealed positive impact of GnRH administration on progesterone profile during mid luteal phase of estrous cycle, which could be used to improve fertility in buffaloes. پرونده مقاله