The study was conducted on postpartum (≥ 90 days) acyclic Sahiwal cows (n= 24), which were randomly divided into three treatment (n=18) and a control group (n=06). Animals of all three treatment groups were treated with GnRH @ 10 µg i/m on day 0 with intra-vaginal placement of CIDR® containing 1.38 g progesterone for 7 days. Animals were treated with i/m injection of PMSG@ 300 IU on day 5, which was followed by administration of PGF2α (Cloprostenol) @ 500µg i/m on day 7. Animals of Group-I were treated with second dose of GnRH on day 9, while animals of Group-II were administered with Estradiol Benzoate (EB) @ 5 mg i/m. No treatment was given to animals of Group-III on day 9 and animals were observed for sign of estrus and A.I. was carried out at detected estrus up to 72 hrs. Fixed time artificial insemination (FTAI) was carried out at 16-22 hrs after 2nd dose of GnRH in Group-I and EB in Group-II. No treatment was given to animals of control group. Secondary signs of estrus were recorded in all animals of treatment groups. Mean follicular diameters (mm) on day of A.I. were 16.85±1.1, 15.2±0.88 and 14.22±0.65 with ovulation rate of 100%, 83% and 66.6% in animals of Group-I, II and III, which subsequently recorded conception rate of 83.3%, 66.6% and 66.6% respectively. A significant difference (P ≤ 0.05) in mean follicular diameter was observed between animals of Group I and Group III. The highest conception rate was recorded in animals of Group I, which exhibited the largest mean follicular diameter and the highest ovulation rate.
Paikra et al. (Thu,) studied this question.
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