STUDIES ON ESTRUS SYNCHRONIZATION AND FOLLICULAR DEVELOPMENT PATTERN IN ONGOLE COWS
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Date
2012-07
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT:
The present investigation was aimed to study the follicular dynamics, serum progesterone concentration during postpartum and effect of GnRH and PGF2α analogues to induce estrus in postpartum anoestrus lactating Ongole cows to reduce the service period. In the ultrasound monitoring of present study in thirteen cows, follicles measuring above 6 mm diameter and corpus luteum measuring 8-10 mm were detected by day 20-25 postpartum period In the present study, the first and second wave of the dominant follicle emerged on day 1.80 + 0.8 and 12.46 + 0.20 days. Where as in three wave cycles first, second and third waves emerged on 1.52 + 0.03, 9.60 + 0.40 and 15.14 + 1.13 days of the estrous cycle, respectively. The mean follicle diameter of the dominant follicles determined by ultrasonography of the ovaries. The first and second wave pattern revealed that 10.23 + 0.40 and 12.30 + 0.36 mm in the two wave cycle. It was observed in the present study that the first wave dominant follicle of three wave cycles attained a maximum size of 10.70+0.20 mm with a mean growth rate of 0.87+0.03 mm per day. In the second wave of the dominant follicle maximum size was 9.80+0.37 mm with growth rate of 0.77+0.06 per day and the third wave maximum diameter was 12.80+0.37 mm with a mean growth rate of 1.46+0.90 mm per day, which is significantly (P< 0.05) bigger and faster in growth rate than the first and second waves in the same estrous cycle. However, the growth rate of second wave and third wave were not significant (P<0.05). In the present study, in natural cycle, the corpus luteum grew to a mean value of maximum diameter of 15.93 + 0.37 and 17.8 + 0.37 mm on the day of 13.1+1.50, 14.6+0.56 and remained up to 14.6+ 1.50 and 15.9+0.45 days of the estrous cycle in two and three wave cycles, respectively.
The wave emergence initiated by the GnRH administration was recorded in the recent study was 1.33+0.21 days and the dominant follicle grew to the maximum diameter of the 12.48 + 0.57 mm with a growth rate of 1.66 + 0.26 mm per day.
In the present investigation about 22.85 per cent (16/70) of the postpartum lactating Ongole cows have shown estrus by day 60 out of seventy postpartum cows. The postpartum onset of behavioral estrus was highly variable and varied from 25 – 195 days with a mean value of 109.50 + 4.66. Estrus was exhibited by 32.50 and 62.50 per cent cows during the day and night time respectively. In the present study, estrus behaviour was classified as intense, normal and weak. Only 18.75 per cent of cows exhibited intense and 18.75 per cent cows exhibited weak estrus and the remaining (62.50 per cent) cows showed normal estrus. In the present study, the mean estrus duration recorded in Ongole cows was 18.23 + 4.20 hours and the mean estrous cycle length was 21.50+0.21 days.
In the present study, 56.25, 57.14 and 100.00 per cent cows required one, two or more artificial inseminations per conception. The mean time required for conception after calving was recorded as 163.60+10.72 (75 -200) days.
The serum progesterone concentration increased steadily from day 0 to 10 in cyclic cows and further increased in fertile cows from day 17 to 25 after breeding and there was a sharp decline in progesterone levels between day 17 to 25 (estrus).
Among the postpartum anoestrus cows synchronized with GnRH + PGF2α + GnRH (Group A) and PGF2α at 12 days interval (Group B) the reproductive performance of group B was found to be better.
The mean conception rate was recorded as 46.15+0.21, 54.54 + 0.36 and 67.00+0.26 in natural estrus , group A and group B, respectively. The conception rate in natural estrus was significantly (P<0.05) lesser than induced groups.
The overall mean time interval from parturition to conception in natural postpartum lactating Ongole cows in control (group C) was 163.60+ 10.72 days with a range of 75-200. Where as the same in treatment groups was 84.95+3.79 with a range of 70-117 in group A and 89.40 + 3.89 with a range of 70-115 days in group B. The statistical analysis of the data revealed that the service period in treatment groups was significantly (P<0.01) shorter than control group (Group C).
From this study, it may be concluded that, treatment of postpartum cows at day 60 with GnRH and PGF2α enhances the fertility significantly (P<0.01) and reduces the service period.
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