Journal of Veterinary and Animal Sciences

Volume: 55 Issue: 1

  • Open Access
  • Research Article

Ultrasonographic studies on ovarian characteristics in cows exhibiting prolonged and normal oestrus

R. S. Athira1, C. P. Abdul Azeez1*, K. Promod1, Leeba Chacko1, S. Pramod2 and Renjith Sebastian3

1. Department of Animal Reproduction, Gynaecology and Obstetrics College of Veterinary and Animal Sciences Pookode, Wayanad-673576 Kerala Veterinary and Animal Sciences University Kerala, India

2. Livestock Research Station, Thiruvizhamkunnu, Kerala Veterinary and Animal Sciences University Kerala, India

3. Department of Veterinary Biochemistry, CVAS, Pookode, Kerala Veterinary and Animal Sciences University Kerala, India

*Corresponding author: [email protected], Ph. 9847701028

Year: 2024, Page: 172-177, Doi:

Received: Oct. 13, 2023 Accepted: Jan. 5, 2024 Published: March 31, 2024


Crossbred cows exhibiting prolonged oestrus (oestrus duration > 36 h, n=6, Group I) and normal oestrus duration (n=6, Group II) which are negative for cytological endometritis, were selected for the present study. Ovaries were subjected to ultrasonographic examination on day 0 (day of oestrus) at, 12 h intervals until ovulation, day 10, 15, and 20 of the oestrus cycle to study the changes in the ovarian structure (follicles and corpus luteum (CL)). On day 0, no significant difference (p>0.05) was observed in the largest follicle size between groups I and II (11.02 ± 0.73 vs 10.94 ± 1.03 mm). In contrast, a significant difference (p< 0.05) was noticed in the diameter of the largest follicle on day 1 (11.7 ±0.68 vs 5.48 ± 2.55 mm). In cows exhibiting prolonged oestrus persistence of pre-ovulatory follicle was observed between 36-48 h in three cows (50 %), between 48-60 h in two cows (33.33%) and between 60-72 h in one cow (16.66%) whereas in animals exhibiting normal oestrus, the pre-ovulatory follicle persisted for < 24 h. The mean diameter of CL on days 10, 15 and 20 in cows exhibiting prolonged oestrus and normal oestrus were 20.53 ± 1.43, 17.34 ± 0.96, 14.78 ± 1.21 mm and 21.62 ± 1.62, 19.20 ± 1.26, 13.7 ± 91.1mm, respectively. A decrease in the rate of CL regression was observed on day 20 of the oestrus cycle in animals exhibiting prolonged oestrus compared to normal oestrus. Hence, it can be inferred that B-mode ultrasonography could be a reliable non-invasive tool to study the ovarian characteristics in cows exhibiting prolonged oestrus.

Keywords: Crossbred cow, prolonged oestrus, normal oestrus, ultrasonography, ovarian characteristics


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Cite this article

Athira, R.S., Azeez, A., Promod, K., Chacko, L., Pramod, S., and Sebastian, R. 2024. Ultrasonographic studies on ovarian characteristics in cows exhibiting prolonged and normal oestrus J. Vet. Anim. Sci. 55(1):172-177