Hormonal and metabolic effects on antral follicle count in dairy cows

This study aimed to investigate the relationship between antral follicle count (AFC) and hormonal profiles as well as metabolic status in dairy cows. A total of 32 Holstein cows aged between 2 and 4 years and in their 60th day of lactation were included. Based on ultrasonographic evaluations, the cows were divided into two groups according to their AFC: low AFC ( 0.05). However, E2 levels on Day 9 were significantly higher in the low AFC group compared to the high AFC group (P = 0.004). Additionally, P4 levels were significantly higher in the low AFC group on Days 0, 6, and 9 (P < 0.05). In contrast, BHBA levels were significantly elevated in the high AFC group across all time points (P < 0.05). Cholesterol levels were consistently higher in the low AFC group throughout the study (P < 0.05). In conclusion, the findings suggest that AFC has a significant effect on hormonal profiles and energy metabolism in dairy cows. Particularly, the elevated steroid hormone levels observed in the low AFC group may reflect a compensatory mechanism to sustain reproductive function in conditions of limited follicular reserve.