EVALUATION OF OVULATION PATTERN AND ITS RELATION TO FERTILITY IN CROSSBRED COWS WITH PROLONGED ESTRUS
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Date
2017-12
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT:
The present investigation “Evaluation of ovulation pattern and its relation to
fertility in crossbred cows with prolonged estrus” was carried out in 48 repeat
breeding cows with known history of prolonged estrus and 12 normal breeding cows
and observed the various aspects of estrus viz. behavioural signs, duration of estrus,
estrus cycle length, follicular growth pattern and hormonal profiles of normal and
prolonged estrus cows. The treatment with GnRH, hCG and clitorial massage were
exercised in repeat breeding cows with prolonged estrus. All the selected animals
were inseminated when follicle diameter reached >12mm on ultra scan examination.
The behavioural signs of estrus viz. bellowing, mounting, lordosis, pink
colouration of vaginal mucous membrane, thin consistency of estrual discharge
were remained for a longer period (≥ 72 h) in prolonged estrus cows than of normal control (≤ 24 h). There was a significant difference in estrus duration between
prolonged (84.0 ± 6.2667 h) and normal estrus (≤24 h) cross bred cows. The
frequency distribution of estrus cycle length was similar between normal (21.25 ±
0.5093 days) and prolonged estrus (21.166 ± 0.6009 days) cows.
The plasma concentrations of E2 was found to be 20.671 ± 1.336, 22.484 ±
1.490, 25.283 ± 1.530, 26.91 ± 1.12, 29.0 ± of 1.50 and 12.097 ± 0.84 pg/ ml on Day
1, Day 2, Day 3, Day 4 and Day 5 of estrus and Day 7 post AI respectively in
prolonged estrus cows. Where as in control it was recorded as 24.0783 ± 0.7644
pg/ml on day of standing estrus and 11.9847 ± 0.7614 on day 7 post AI. There was
no significant difference between two groups of cows. Interestingly concentration of
estradiol on alternative days shown a significant increase (p ≤ 0.05).
The plasma concentration of P4 was significantly higher (suprabasal level) in
prolonged estrus group (> 0.4 ng/ml) than of normal control (basal level <0.4
ng/ml). There was no statistical significance during estrus of prolonged estrus group.
However, there was a significant difference between days of estrus and day of CL in
prolonged estrus group. The mean of maximum diameter of pre ovulatory follicle (13.4125 ± 0.30 Vs 13.2 ± 0.12 mm) and CL diameter (17.8495 ± 1.0893 Vs 17.9971± 1.1219 mm)
were not significant in prolonged estrus group and normal estrus group respectively.
In prolonged estrus group the mean diameter follicle increased non significantly at
successive days, but the increase was significant at alternate days (P ≤ 0.05). The
conception percentage was not enhanced appreciably with treatment.
In this present study the term ‘follicular persistence’, ‘persistent dominance’
and ‘delayed ovulation’ might not be appropriate terms to be used.
It was concluded that it might be tempting to presume that probably there
could have been stress mediated altered endocrine events in follicular growth
resulting in overlapping of proestrus and estrus and thus an apparently extended
estrus.
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