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ThesisItem Open Access ULTRASONOGRAPHIC MONITORING OF OVARIAN FOLLICULAR AND LUTEAL DYNAMICS IN COW(College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2022-03) RALTE, VANLALNGILNEII; Dutta, DevojyotiThe ovarian follicular and luteal dynamics, blood flow pattern in the corpus luteum (CL) including the pattern of follicular wave and luteal development were studied using portable ultrasound device with 5-10 MHz linear array transrectal probe in female Crossbred and Lakhimi, indigenous cattle breed of Assam. In the experiment, twelve each cyclic Crossbred (Jersey X L) and Lakhimi (L) cows were subdivided into two groups viz. Group-I/Natural or Spontaneous oestrus and Group-II/Induced or Synchronized oestrus for each breed comprising of six cows in each group. They were evaluated in the subsequent cycle of natural luteolysis (Group-I) and induced luteolysis by prostaglandin F2α (Group-II) and circulating steroids were estimated on alternate days of the cycle. From scanning the ovaries for two inter-ovulatory cycle the experimental cows exhibited two and three follicular waves per cycle. Most of the cows 30(62.50 %) exhibited 3-wave cycle and 18(37.50 %) had 2-wave cycle. The diameter of 12.4 mm and 10.5 mm were the threshold diameter for ovulation according to follicle diameter in crossbred and Lakhimi cows, respectively. The inter-ovulatory interval (IOI) was found to be significantly longer (P<0.05) in Crossbred cows experiencing 3-wave (21-22 day) than 2-wave (20-21 day) per cycle. The first wave emerged on day 0 (day of ovulation) to day 1 of cycle with mean day of 0.13 ± 0.12 to 0.83 ± 0.38 in both the breed and group. The second wave onset was significantly (P < 0.05) earlier (9.00 ± 0.19, 8.50 ± 0.22) in 3-wave cycle than the 2-wave cycle (10.50 ± 0.29, 10.67 ± 0.21) in both Crossbred and Lakhimi cows. The average number of follicles (≥ 2 mm) observed on wave onset was 10-13 in Crossbred and 9-13 in Lakhimi cows. The first wave dominant follicle (DF) became deviated in between day 3 to 4 in both the breeds, while the second wave DF deviated on day 11-12 in Crossbred and day 10-11 in Lakhimi cows exhibiting 2-wave cycle. Deviation of the third DF occurred on day 17-18 in both the breeds. Maximum mean diameter of DF in the second waves recorded as 8.74 ± 0.52 and 7.70 ± 0.27 mm in Crossbred and Lakhimi cows respectively in 3-wave cycles was significantly smaller (P < 0.05) than the second wave DF diameter (12.83 ± 0.65 and 10.53 ± 0.76 mm) in 2-wave cycles in both crossbred and Lakhimi cows. The DF maximum diameter was attained significantly (P < 0.05) earlier in 3-wave cycle in both the first and second wave than in 2-wave cycle. The average growth rate of ovulatory DF in 3-wave cycle was 1.19 and 1.37 mm/day in Group-I and II respectively in Crossbred while, 0.88 and 1.18 mm/day in Group-I and II respectively in Lakhimi. The dominant follicles of the first wave (non-ovulatory) began atresia on day 8.0 ± 0.41 at the rate of 1.36 to 1.53 mm/day in Crossbred cow and on day 7.75 ± 0.25 at the rate of 0.97 mm/day in Lakhimi cows. The developing CL was detected on day 0 to day 1 in both Crossbred and Lakhimi cows. Maximum diameter (mm) of the CL for the two and three follicular wave cycle in Lakhimi (15.29 ± 0.64 mm and 15.08 ± 0.45 mm) were significantly smaller (P <0.05) than in Crossbred cows (22.98 ± 0.87 mm and 21.94 ± 0.66 mm). Onset of luteal regression of the 2-wave cycles (day 12 to 13 ) was significantly earlier (P < 0.05) than in the 3-wave cycle (day 15 to 16 ). In early luteal phase (day 0 to 5) the Doppler signal increased to 65.73 ± 5.02 mm2 in Crossbred and 57.30 ± 9.83 mm2 in Lakhimi. During the mid-luteal phase (day 7 to 13) the area gradually increased to 119.82 ± 5.54 mm2 in Crossbred and 93.82 ± 4.12 mm2 in Lakhimi cows then rapidly declined in the late luteal phase (day 15 to 18) to 10.66 ± 2.02 mm2 in Crossbred and 11.99 ± 5.38 mm2 in Lakhimi. Similar pattern was observed in 2-wave cycle. On the day of oestrus, the mean serum Oestradiol-17β level ranged from 35.75 ± 0.64 to 51.01 ± 2.13 pg/ml in Crossbred and 32.43 ± 0.74 to 35.74 ± 0.97 pg/ml in Lakhimi while the serum progesterone level ranged from 0.58 ± 0.71 to 1.27 ± 0.33 ng/ml in crossbred and 0.43 ± 0.77 to 0.47 ± 0.76 ng/ml in Lakhimi cows. ii There was a positive correlation between LBF area and progesterone level in 2-wave crossbred (r = 0.92), 2-wave Lakhimi (r= 0.82), 3-wave crossbred (r = 0.81) and 3-wave Lakhimi (r = 0.90) during the cycle. There was positive correlation between DF size and oestradiol level in 2-wave (r = 0.40) also in 3-wave crossbred and Lakhimi cows (r = 0.41). Negative correlation was observed between DF size and progesterone level in 2-wave (r = - 0.47) and in 3-wave (r = - 0.40) in crossbred and Lakhimi cows.
