Ovarian follicular and luteal dynamics during natural and hormonally induced estrus in Arunachali yak (Bos grunniens)
- 1ICAR-National Research Centre on Yak, Dirang, Arunachal Pradesh, India
- 2College of Veterinary Science, AVFU, Guwahati, Assam, India
- 3Lakhimpur College of Veterinary Science, AVFU, Joyhing, Assam, India
Abstract
This study investigated follicular growth patterns, corpus luteum dynamics and endocrine profiles during natural and hormonally induced estrous cycles in Arunachali yak maintained at the ICAR–NRC on Yak, Nyukmadung, Arunachal Pradesh, India. Thirty-six apparently healthy, cyclic female yaks of second to fourth parity were equally assigned to natural estrus (Group I) or hormonally induced estrus using a modified Ovsynch protocol (Group II). Daily transrectal ultrasonography was performed throughout one estrous cycle to characterize follicular waves and luteal dynamics, along with serial endocrine profiling. Three follicular-wave patterns were observed in natural cycles and four in induced cycles. A two-wave pattern predominated in natural estrus (66.67%), whereas a three-wave pattern predominated following hormonal induction (77.78%). The mean estrous cycle was significantly longer in induced than natural cycles (22.50 ± 0.35 vs. 20.00 ± 0.70 days). The first follicular wave was the longest in both groups, with successive waves showing progressively shorter durations. Corpus luteum size differed significantly between groups, indicating altered luteal dynamics following hormonal induction. Endocrine profiling further showed higher progesterone (5.75 ± 0.13) during induced cycles, increased estradiol (29.20 ± 3.19) at subsequent estrus and the third follicular peak, increased IGF-1 (124.63 ± 2.97) during the mid-and late-luteal phases and elevated cortisol (3.47 ± 0.25) during the early-to-mid luteal phase. Overall, hormonal induction altered follicular-wave patterns, cycle length, luteal development and endocrine dynamics in Arunachali yak. These findings facilitate the optimization of estrus synchronization and fixed-time artificial insemination (FTAI) protocols, thereby enhancing ovulatory precision and overall reproductive performance in yaks (Bos grunniens).
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BibTeX
@article{hussain2026ovarian,
title = {{Ovarian follicular and luteal dynamics during natural and hormonally induced estrus in Arunachali yak (Bos grunniens)}},
author = {Mokhtar Hussain and Lalit Kumar Patel and Arunoday Das and Supriya Bera and Dhrubajyoti Borpujari and Pranjal Borah and Dinamani Medhi and Vijay Paul and Mihir Sarkar},
journal = {Frontiers in Veterinary Science},
year = {2026},
month = oct,
doi = {10.3389/fvets.2026.1967091},
url = {https://doi.org/10.3389/fvets.2026.1967091},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Ovarian follicular and luteal dynamics during natural and hormonally induced estrus in Arunachali yak (Bos grunniens)
AU - Mokhtar Hussain
AU - Lalit Kumar Patel
AU - Arunoday Das
AU - Supriya Bera
AU - Dhrubajyoti Borpujari
AU - Pranjal Borah
AU - Dinamani Medhi
AU - Vijay Paul
AU - Mihir Sarkar
PY - 2026
DA - 2026/10/12
JO - Frontiers in Veterinary Science
DO - 10.3389/fvets.2026.1967091
UR - https://doi.org/10.3389/fvets.2026.1967091
AB - This study investigated follicular growth patterns, corpus luteum dynamics and endocrine profiles during natural and hormonally induced estrous cycles in Arunachali yak maintained at the ICAR–NRC on Yak, Nyukmadung, Arunachal Pradesh, India. Thirty-six apparently healthy, cyclic female yaks of second to fourth parity were equally assigned to natural estrus (Group I) or hormonally induced estrus using a modified Ovsynch protocol (Group II). Daily transrectal ultrasonography was performed throughout one estrous cycle to characterize follicular waves and luteal dynamics, along with serial endocrine profiling. Three follicular-wave patterns were observed in natural cycles and four in induced cycles. A two-wave pattern predominated in natural estrus (66.67%), whereas a three-wave pattern predominated following hormonal induction (77.78%). The mean estrous cycle was significantly longer in induced than natural cycles (22.50 ± 0.35 vs. 20.00 ± 0.70 days). The first follicular wave was the longest in both groups, with successive waves showing progressively shorter durations. Corpus luteum size differed significantly between groups, indicating altered luteal dynamics following hormonal induction. Endocrine profiling further showed higher progesterone (5.75 ± 0.13) during induced cycles, increased estradiol (29.20 ± 3.19) at subsequent estrus and the third follicular peak, increased IGF-1 (124.63 ± 2.97) during the mid-and late-luteal phases and elevated cortisol (3.47 ± 0.25) during the early-to-mid luteal phase. Overall, hormonal induction altered follicular-wave patterns, cycle length, luteal development and endocrine dynamics in Arunachali yak. These findings facilitate the optimization of estrus synchronization and fixed-time artificial insemination (FTAI) protocols, thereby enhancing ovulatory precision and overall reproductive performance in yaks (Bos grunniens).
SN - 2297-1769
ER -