Artificial insemination (AI) after estrus induction is one of the best reproductive bio-techniques that will help in progressing animal agriculture into the new era. Reproductive efficiency of cow and heifer is an important factor that influence the profitability of any dairy enterprise. Different experiments were conducted to compare the efficacy of estrus synchronization protocols through estrus response and fertility rate in cattle during non-breeding and breeding seasons. Determination of time of ovulation and ovulatory response through peripheral LH surge, progesterone (P4) rise and follicular dynamics were also studied during non-breeding season. A total of 312 non-descript cows and heifers (averaging 3 to 4 years) with body condition score (BCS) ranges between 3.0 to 3.5 were randomly assigned to receive Ovsynch, CIDR alone and CO-Synch+CIDR protocols. Animals were inseminated at 16 h after the injection of second GnRH in Ovsynch, and 48 h after CIDR removal in CIDR inserted groups. The duration of induced estrus in non-descript cows was similar (P = 0.79) to natural estrus whereas, the duration of standing heat was significantly (P < 0.05) increased in induced cows (9.69 ± 0.62 h) compared to non-induced cows (6.66 ± 0.80 h). The results revealed that the Ovsynch protocol was slightly better in terms of inducing heat and enhanced the conception rate (CR) in indigenous cows under farm (87.5%) and field (50.0%) conditions during non-breeding season. In case of non-descript heifers, duration of induced estrus with an average of 18.63 ± 1.03 h, similar (P > 0.05) to natural estrus (18.00 ± 1.58 h). However, a significant difference (P < 0.05, t(18)= 2.515) was observed between the duration of induced (10.63 ± 0.60 h) and natural (8.25 ± 0.73 h) standing heat. It was observed that treatment with CO-Synch+CIDR enhanced the CR at timed artificial insemination (TAI; P > 0.05) in indigenous heifers under farm (50.0%) and field (33.33%) conditions during non-breeding season. To achieve further improvements in results, hormonal analysis and ultrasonography were performed to determine the time of ovulation and to establish the AI at a fixed time without the need for estrus detection. A better synchronous LH peak was observed in Ovsynch group (48.40 ± 0.40 h post PGF2α administration) compared to CIDR alone (71.67 ± 9.74 h) and CO-Synch+CIDR (54.86 ± 4.71 h) protocols. The ovulatory response was induced in 100% cows with Ovsynch and CO-Synch+CIDR protocols as indicated by LH surge and progesterone level; only 83.33% cows responded to CIDR alone treatment during non-breeding season (P > 0.05). The mean follicular diameter (13.98 ± 1.15), growth rate (1.43 ± 0.15) and ovulation rate was highest (100%) with Ovsynch treatment compared to CIDR alone and CO-Synch+CIDR, but the difference was non-significant (P > 0.05). The interval between PGF2α and ovulation was shorter in Ovsynch (77.0 ± 6.0 h) group compared to CIDR alone (93.60 ± 10.32 h) and CO-Synch+CIDR (79.20 ± 2.93 h) groups. The interval between LH surge and ovulation was 28.50 ± 5.85 h, 24.80 ± 7.31 h and 22.0 ± 5.55 h in Ovsynch, CIDR alone and COSynch+ CIDR groups respectively. During breeding season, CR/TAI was similar (47%) in all groups of non-descript cows under field conditions. It was observed that CO-Synch+CIDR treatment yielded the satisfactory (P < 0.05) conception rates under farm conditions compared to field conditions in non-descript heifers. The application of estrus synchronization protocols significantly (P < 0.0001) reduced the service period in non-descript cows and age at first calving in crossbred cows. It is concluded that during non-breeding season, Ovsynch can be an advantageous protocol for non-descript cows and CO-Synch+CIDR for heifers which showed good estrus expression and fertility, and thus, reduce the maintenance cost of dry animals, which in fact is of economic importance to the farmers. During breeding season conception rates at TAI were satisfactory in all groups of cows under field conditions. Treatment of cows and heifers with estrus induction protocols will yield acceptable pregnancy rates.