This experiment was performed to access the effect of different hormonal protocols during breeding season of mares (March to August) in Punjab. A total of 25 Marwari mares with regular oestrous cycle were selected betweenage group of 4-12 years and divided randomly into 3 groups. Group 1 (n=10) mares were treated with Estrumate (PG) and Chorulon (HcG) based protocol. The ovarian status of each mare was detected by ultrasonography. Mares having mature corpus luteum (CL) and medium size

(20 mm-24 mm) growing follicle (day 1) were injected with Estrumate (cloprostanol sodium 500 μg) 2 ml intramuscularly on day 1 morning and then on morning of 6th day injection Chorulon (3000 I.U.) was administered intravenously. On day 14 mares were again injected with Estrumate 2 ml intramuscularly followed by injection chorulon 3000 I.U. intravenously on 20th day morning. In group 2 (n=10) mares were injected with single injection of Estrumate 2 ml intramuscularly after detection of mature CL and medium size growing follicles (20-24 mm). In group 3 (n=5) all mares were covered during natural oestrus. Mares in all groups were covered twice at 36 hours interval after detection of dominant follicle (≥30 mm diameter), clinical oestrus signs and teasing score. The conception rates were 70% (7/10), 60% (6/10) and 60% (3/5) in Group 1, 2 and 3 respectively. Mares of group 1 had better pregnancy rate than other groups hence it was concluded that exogenous administration of hormones for oestrus synchronization in Marwari mares was quite beneficial and also reduced the rearing cost of the stud farmers.

Highlights

• Unawareness among breeders for synchronization of oestrus by using different hormonal regimens results in increased incidence of various reproductive disorders.
• The conception rate was best in the group treated with PG and HcG based protocol.
• The use to exogenous hormones is quite helpful in synchronization of estrus and timely ovulation in mares which increases the chances of conception during breeding season.