Evaluation of Ovsynch Estrus Synchronization in Holstein Friesian and Holstein Friesian-Jersey Crossbred Cows at District Thatta, Sindh, Pakistan

The current study was conducted to assess the ovsynch estrus synchronization in imported pure Holstein Friesian and Holstein Friesian-Jersey crossbred cows at district Thatta Sindh. A total 30 Holstein Friesian and Holstein Friesian-Jersey crossbred cattle were selected and divided into three groups i.e., A (10 pure Holstein Friesian cows), B (10 Holstein Friesian-Jersey crossbred cows), and C (5 pure Holstein Friesian and 5 Holstein Friesian–Jersey crossbred cows) as control group. All selected animals were scanned through ultrasound to ensure the normality of reproductive tract. Animals of group A and group B were treated with Ovsynch protocol {GnRH; (Dalmarelin, FATRO) intramuscular at day 0 followed by PGF2α (Dalmazin; FATRO) intramuscular at day 7 and 2 nd GnRH intramuscular at day 9} for estrus synchronization while animals of group C was kept as untreated control (intramuscular injection of normal saline as placebo on day 0, 7 and 9). Animals of all group underwent fixed time insemination at 16 h of last treatment. Results showed that estrus response vary significantly among the groups (P<0.05). Overall estrus response was observed significantly higher in group B (80%), followed by A (60%) and C (10%). Intensity of estrus was determined by observing the estrus signs. Results showed significantly higher intensity of estrus signs in Group B than A and C for mucus discharge 90%, 65%,10%, flehmen 90%, 60%,10%, standing heat80%, 60%, 10% and sniffing vagina 80%, 70%, 10%, respectively. Estrus duration differs significantly among the treatment groups (P<0.05). Significantly maximum estrus duration was noted in group B (15.02 ± 0.21 h), then A (13.58 ± 2.22 h) and C (10 ± 0.00 h). In all groups blood samples were collected from the milk vein on day 0 (the first treatment), day 7, day 11 (one day after artificial insemination), day 18 and day 30 from all groups for determining progesterone level. Statistical analysis showed non-significant differences in progesterone level among groups at day 0. Furthermore, on Day 7, Group C differed significantly in progesterone level than A and B; however non-significant difference were observed in group A and B, while in group C difference was significant. On day 11 significantly highest values of blood progesterone were seen in group C (2.63 ± 0.22) followed by A (1.65 ± 0.35) and then B (1.48 ± 0.22). Statistical analysis showed that group C was significantly different from A and B, but there was non-significant difference between A and B. At day 18 highest P4 values were seen in B (4.20 ± 0.44) followed by A (3.33 ± 0.39) and then C (1.88 ± 0.59). Statistical analysis showed that group B and A had non-significant difference among each other, while both groups had significant differences with group C. Blood progesterone level for all the three groups on day 30 showed highest values in group B (10.90 ± 2.44) followed by A (8.28 ± 3.33) and C (4.53 ± 0.44). Statistical analysis showed significant difference among all three groups on day 30. It was concluded that in term of estrus response, cyclic activities and fertility rate, Ovsynch protocol was more effective in Holstein Friesian- Jersey cross breed cows than in Holstein Friesian pure cows.