Follicle Selection in Cattle: Follicle Deviation and Codominance Within Sequential Waves

• Published in: Biology of reproduction 2001-09, Vol.65 (3), p.839-846
• Main Authors: KULICK, L. J, BERGFELT, D. R, KOT, K, GINTHER, O. J
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cattle - physiology; Estradiol - blood; Female; Follicle Stimulating Hormone - blood; Fundamental and applied biological sciences. Psychology; Kinetics; Luteinizing Hormone - blood; Mammalian female genital system; Morphology. Physiology; Ovarian Follicle - diagnostic imaging; Ovarian Follicle - physiology; Ovulation; Time Factors; Ultrasonography; Vertebrates: reproduction
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod65.3.839

Follicle deviation during bovine follicular waves is characterized by continued growth of a developing dominant follicle and reduction or cessation of growth of subordinate follicles. Characteristics of follicle deviation for waves with a single dominant follicle were compared between wave 1 (begins near ovulation; n = 15) and wave 2 (n = 15). Follicles were defined as F1 (largest), F2, and F3, according to maximum diameter. No mean differences were found between waves for follicle diameters at expected deviation (F1, ≥8.5 mm; Hour 0) or observed deviation or in the interval from follicle emergence at 4.0 mm to deviation. For both waves, circulating FSH continued to decrease ( P < 0.05) after Hour 0, estradiol began to increase ( P < 0.05) at Hour 0, and immunoreactive inhibin began to decrease ( P < 0.05) before Hour 0. A transient elevation in circulating LH reached maximum concentration at Hour 0 ( P < 0.01) in both waves and was more prominent ( P < 0.0001) for wave 1. Waves with codominant follicles (both follicles >10 mm) were more common ( P < 0.02) for wave 1 (35%) than for wave 2 (4%). Codominants (n = 6) were associated with more ( P < 0.05) follicles ≥4 mm and a greater concentration ( P < 0.04) of circulating estradiol at Hours −48 to −8 than were single dominant follicles (n = 15). A mean transient increase in FSH and LH occurred in the codominant group at Hour −24 and may have interfered with deviation of F2. In codominant waves, deviation of F3 occurred near Hour 0 (F1, approximately 8.5 mm). A second deviation involving F2 occurred in four of six waves a mean of 50 h after the F3 deviation and may have resulted from a greater suppression ( P < 0.05) of FSH in the codominant group after Hour 0. In conclusion, follicle or hormone differences were similar for waves 1 and 2, indicating that the deviation mechanisms were the same for both waves. Waves that developed codominant follicles differed in hormone as well as follicle dynamics.