Corpus luteum dynamics after ovulation induction with or without previous exposure to progesterone in prepubertal Nellore heifers

Abstract

The objectives of this study were 1) to monitor corpus luteum (CL) dynamics after two different protocols of ovulation induction in prepubertal Nellore heifers, and 2) to determine differences in luteal function. Fifty-seven heifers (weight 289.61 ± 32.28 kg, BCS 5.66 ± 0.65, age 17.47 ± 0.81 months) were divided into two groups: GP4+GnRH received a progesterone (P4) device of 3rd use for 10 days, followed by the administration of 0.02 mg buserelin acetate (GnRH) 48 h after removal of the device, and GGnRH received only GnRH. The CLs formed were monitored by ultrasonography every 2 days until their functional regression (decrease in the color Doppler signal and serum P4 concentration < 1 ng/mL), determining their diameter and area, numerical pixel value (NPV), pixel heterogeneity, and vascularization percentage. The peak systolic velocity, end diastolic velocity, resistivity index and pulsatility index (PI) of the ovarian artery and serum P4 concentration were also measured. A lifespan of the CL of more than 16 days was classified as normal-function and of less than 16 days as premature regression. The variables were compared between treatments, CL categories (normal-functional, prematurely regressed or non-functional), days of evaluation, and their interactions using the MIXED procedure of the SAS program (p ≤ 0.05). Three animals of each group (6/57 = 11%) did not respond to treatment, corresponding to an ovulation rate of 89%. There was a higher percentage of normal-function CLs in GP4+GnRH (81%) and a higher percentage of non-functional CLs in GGnRH (52%; P4 concentration < 1 ng/mL in all assessments). Normal-function CLs exhibited a greater area, vascularization percentage and P4 concentration than prematurely regressed and non-functional CLs. Lower diameter, area, NPV and P4 concentration were observed for non-functional CLs, but there was no difference in vascularization percentage compared to prematurely regressed CLs. Progesterone concentration was efficient in diagnosing CL function and was positively correlated with CL area (r = 0.62; p < 0.001) and vascularization percentage (r = 0.38; p < 0.001). Diameter and PI were important for the early diagnosis of non-functional and prematurely regressed CLs, respectively. In conclusion, luteal function differed for the first CL that develops after ovulation induction in prepubertal heifers. Ultrasonographic parameters (diameter, area, NPV, vascularization percentage, and PI) can be used to predict CL function.

Caracterización ultrasonográfica modo-B y Doppler del cuerpo lúteo en llamas

“…The echotexture of the LC of recipient llamas effectively shows them to be uniform, circumscribed, hypoechogenic and homogeneous structures (Figure 1), due to the fact that their ovarian stroma is related to the active angiogenic process that occurs during the initial stages of luteal development in mammals, mediated by angiogenic factors such as vascular endothelial growth factor (VEGF), whose increase leads to rapid mitosis of the endothelial cells of the capillaries of the LC14 22,23 , in addition to the fact that most steroidogenic cells are adjacent to one or more capillaries and the perfusion of the luteal blood flow is so intense that it affects the acoustic impedance of the organ, resulting in the characteristic echotexture of the LC12 24 , as occurs in other species with the same hypoechogenic characteristics in relation to the ovarian stroma 25,26 . In B-mode ultrasonography of the CL in recipient llamas show morphometric characteristics such as area, volume and diameter highly related to studies on follicular dynamics in llamas specifically with sizes of donor follicles reaching diameters of 10.0±2.0 mm and 11.8±1.6 mm respectively 3,27 , the maximum follicular diameter is related to the future diameter of the CL since these follicles have active angiogenesis after theca formation, which promotes the permeability of blood vessels, ovulation and subsequent formation of the CL 28 , in cows for meat and milk production, ovulation of a preovulatory follicle of greater diameter leads to a CL of good size; this characteristic seems to be associated with fertility 29,30 .…”

Early luteal development in Santa Inês ewes superovulated with reduced doses of porcine follicle‐stimulating hormone

“…The PI showed to be the first marker for the diagnosis of premature regression in heifers, since females presenting CLs of this category showed higher values of this index in 4th and 6th days after induction of ovulation (Vrisman et al, ). In the present study, PI values were higher on Days 14 and 15 than on Days 11, 12 and 13, which may also be related to regression of part or all of CLs in most (41.35%) of our females.…”

Application of Embryo Transfer Technology to Improve Fertility Using GnRH Plus Progesterone and Estradiol Combination (FTAI) of Local South Pesisir Cow in West Sumatra

“…Thus, the influence of the side of previous pregnancy persisted until the second postpartum ovulation, and this affected postpartum dominant follicle selection and ovulation, but not the development of growing follicles [34]. In addition, postpartum ovarian activity imbalance was not association with the reproductive and productive performance of cows [35]. The relationship between the dominant follicle and CL due to the hormonal concentration such as estrogene and progesterone.…”