Endocrine milieu and developmental dynamics of ovarian cysts and persistent follicles in postpartum dairy cows

Abstract

Ovarian follicular cysts and persistent follicles are follicular pathologies involved in reduced fertility of dairy cows. Two separate experiments were performed on high-yielding Holstein cows to characterize ovarian cyclicity and evaluate the developmental dynamics of follicle pathologies postpartum. In experiment 1, 58 cows were monitored by ultrasonography twice weekly from d 18±1 to 69±2 postpartum. First ovulation occurred 38±3, 27±2, 20±1, and 25±3 d postpartum in cows with 1 cycle (n=11), 2 cycles (n=21), 3 cycles (n=13), and 4 cycles (n=7), respectively. Follicular pathologies were developed in cows that were either acyclic (n=6) or had 1 or 2 cycles, but not in cows with more than 2 cycles. In experiment 2, 47 cows were monitored twice weekly from 10 d postpartum to second ovulation. Follicles ≥17 mm in diameter in 2 consecutive scans were aspirated, and concentrations of various hormones were measured. Cows were defined as cyclic (n=30; 64%) or with the potential to develop follicular pathology (n=17; 36%). Aspirated follicles (n=27) were classified into 3 main groups based on follicular growth rate, follicular diameter, and ovarian activity before and after follicular aspiration. Dominant follicles (n=4) were defined as large follicles (20 mm in diameter) with growth rate ≤1 mm/d and normal ovarian activity. Persistent follicles (n=6) had the same growth rate and diameter as the dominant follicles, but persisted at the same diameter for ≥10 d. Ovarian cysts (n=17) were defined as the largest follicular structures (19 to 32 mm in diameter), with abnormal growth rate (>1 mm/d) and abnormal ovarian activity. Single or turnover cysts did not differ in their growth parameters and were therefore combined and further classified according to follicular-fluid hormone concentrations. Estradiol-dominant cysts (n=7) were characterized by normal estradiol (284 to 659 ng/mL) and progesterone (20 to 113 ng/mL) concentrations, similar to those of the dominant follicle (554 to 993 ng/mL and 44 to 106 ng/mL, respectively). Progesterone-dominant cysts (n=5) were characterized by low estradiol (0.06 to 330 ng/mL) and high progesterone (586 to 3,288 ng/mL) concentrations. Low-steroidogenic active cysts (n=5) were characterized by low concentrations of both estradiol (23 to 61 ng/mL) and progesterone (17 to 205 ng/mL). Characterization of spontaneously forming cysts might enable definition of the formation of ovarian follicular pathologies in postpartum cows.

Thyroidal and Progesterone Hormones in Cows with Ovarian Cysts and Effects of Therapy with Levothyroxine, KI, GnRH and Progesterone or Ovsynch

“…The plasma progesterone concentrations associated with cystic ovaries in this study were similar to those in plasma or milk previously reported in cows with induced or spontaneously occurring cysts (Ribadu et al, 1994;Robinson et al, 2006;Roth et al, 2012;Mutinati et al, 2013;Pusph et al, 2016). …”

ACTH administration during formation of preovulatory follicles impairs steroidogenesis and angiogenesis in association with ovulation failure in lactating cows

“…Cyst formation during the early postpartum period (from calving to 60 d postpartum) varies from 6% to 30% [1,5], presumably because of postpartum stress. For instance, lame cows are 2.6 times more likely to develop an ovarian cyst than nonlame cows [3].…”

“…The major difficulty in studying the underlying mechanism is that cyst formation can only be retrospectively recognized, after the follicle has undergone extensive pathologic changes. Thus, prediction of pathology formation during follicular development is a formidable challenge [1].…”

Acurácia da ultrassonografia e da avaliação comportamental na determinação das características funcionais de estruturas ovarianas císticas

“…A palpação retal é usualmente utilizada no diagnóstico de cistos foliculares em bovinos; porém, apresenta eficiência moderada para detectar estruturas >25 mm e está sujeita a erros nos casos de estruturas císticas menores (Roth et al, 2012). O diagnóstico conclusivo geralmente é feito com base na identificação da estrutura cística em duas avaliações consecutivas, realizadas com intervalo de dez dias, na ausência de corpo lúteo.…”

“…Foram utilizados três rebanhos leiteiros com média de 250 animais em lactação, compostos por animais da raça Girolando, com grau de sangue entre 1/2 e 7/8 Holandês (Roth et al, 2012). Foram registrados o diâmetro médio, em dois eixos perpendiculares, da estrutura cística e a existência ou não de bordo luteinizado (cisto luteinizado) -parede folicular com espessura ≥3 mm e formada por tecido com ecogeinicidade semelhante à de corpo lúteo.…”