The absence of corpus luteum formation alters the endocrine profile and affects follicular development during the first follicular wave in cattle

Abstract

We previously established a bovine experimental model showing that the corpus luteum (CL) does not appear following aspiration of the preovulatory follicle before the onset of LH surge. Using this model, the present study aimed to determine the profile of follicular development and the endocrinological environment in the absence of CL with variable nadir circulating progesterone (P 4 ) concentrations during the oestrous cycle in cattle. Luteolysis was induced in heifers and cows and they were assigned either to have the dominant follicle aspirated (CL-absent) or ovulation induced (CL-present). Ultrasound scanning to observe the diameter of each follicle and blood collection was performed from the day of follicular aspiration or ovulation and continued for 6 days. The CL-absent cattle maintained nadir circulating P 4 throughout the experimental period and showed a similar diameter between the largest and second largest follicle, resulting in co-dominant follicles. Oestradiol (E 2 ) concentrations were greater in the CL-absent cows than in the CL-present cows at day K1, day 1 and day 2 from follicular deviation. The CL-absent cows had a higher basal concentration, area under the curve (AUC), pulse amplitude and pulse frequency of LH than the CL-present cows. After follicular deviation, the CL-absent cows showed a greater basal concentration, AUC and pulse amplitude of growth hormone (GH) than the CL-present cows. These results suggest that the absence of CL accompanying nadir circulating P 4 induces an enhancement of LH pulses, which involves the growth of the co-dominant follicles. Our results also suggest that circulating levels of P 4 and E 2 affect pulsatile GH secretion in cattle.

Metabolic Profile and Hormonal Status Comparison Between Primiparous and Multiparous Non-Cyclic Cows

“…In contrast, CL-absent cows (low P 4 concentration) have been shown to have a higher E 2 concentration than CL-present cows (high P 4 concentration). which in turn leads to a higher LH pulse frequency that enhances the follicular growth (21). Nevertheless, it should be emphasized that, for cows diagnosed as non-cycling, the major underlying factor for compromised follicular development could be the low LH pulse frequency, although, other metabolic hormones like IGF-1, insulin, growth hormone (GH) that are involved and crucial for normal follicular development should not be avoided (3).…”

Effect of manipulating progesterone before timed artificial insemination on reproductive and endocrine parameters in seasonal-calving, pasture-based Holstein-Friesian cows

“…When the ovulatory follicle arises in a follicular wave that develops in the absence of P4 (i.e., no active CL), codominant follicles resulting in double ovulations occur more frequently (Wiltbank et al, 2000;Hayashi et al, 2008). This is particularly the case for anovular cows at first postpartum ovulation, which had a 41% doubleovulation rate, compared with 4% for cycling cows (Gümen et al, 2003).…”

Physiological and practical effects of progesterone on reproduction in dairy cattle

“…For example, cattle that grow the ovulatory follicular wave in the absence of P4 have an increased percentage of cows with co-dominant follicles and double ovulation (Hayashi et al, 2008). Manipulative studies have now been performed that have demonstrated a decrease in the percentage of cows that double ovulate when circulating P4 is increased (Stevenson et al, 2007a;Cunha et al, 2008;Cerri et al, 2011a).…”