Follicular dynamics and concentrations of steroids and gonadotropins in lactating cows and nulliparous heifers

Wolfenson, D.; Inbar, G. F.; Roth, Zvi; Kaim, M.; Bloch, A.; Braw–Tal, R.

doi:10.1016/j.theriogenology.2003.12.020

Cited by 122 publications

(116 citation statements)

References 36 publications

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“…Serum P4 concentration is near to zero around estrus and high during the luteal phase, with average peak levels ranging from 4.1-9.9 ng/ml [4,17,23,38,71]. A high correlation between CL diameter and P4 output was reported in [58,64,81]. However, Adams [4] found a correlation between CL size and P4 serum levels in the early luteal phase only, which could be due to changes in CL vascularity during the cycle, resulting in changes in P4 releasing capacity [46,50].…”

Section: Progesteronementioning

confidence: 87%

“…Small follicles of an emerging cohort may release very small amounts of E2 and Inh per follicle, but taken together, this amount is not negligible. Furthermore, there is always a medium-size or large follicle present [36,80,81], which results in a basal hormone production throughout the cycle. The capacity of follicles to produce E2 and Inh is denoted as "follicular function" in the rest of this paper.…”

Section: Follicle Developmentmentioning

confidence: 99%

“…Continued CL growth is stimulated by autocrine and paracrine mechanisms [68]. The CL develops within 2-3 days after ovulation, grows until a maximum diameter of about 30 mm, and starts to regress at day 17-18 of the cycle [50,73], although P4 levels may start to decline earlier [81]. The primary function of the CL is P4 secretion.…”

Section: Corpus Luteummentioning

confidence: 99%

“…Besides direct effects of E2 on the pituitary, E2 stimulates the LH surge because it stimulates GnRH [32]. The LH surge will shut down E2 and Inh production capacity of the ovulatory follicle [12,81] and induces a shift from E2 to P4 production [19]. LH level in the blood declines because the LH content of the anterior pituitary is reduced and further LH synthesis therein and release to the blood is decreased because E2 is decreased.…”

Section: Luteinizing Hormonementioning

confidence: 99%

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A simple mathematical model of the bovine estrous cycle: Follicle development and endocrine interactions

Bôer

Stötzel

Röblitz

et al. 2011

Journal of Theoretical Biology

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Bovine fertility is the subject of extensive research in animal sciences, especially because fertility of dairy cows has declined during the last decades. The regulation of estrus is controlled by the complex interplay of various organs and hormones. Mathematical modeling of the bovine estrous cycle could help in understanding the dynamics of this complex biological system. In this paper we present a mechanistic mathematical model of the bovine estrous cycle that includes the processes of follicle and corpus luteum development and the key hormones that interact to control these processes. The model generates successive estrous cycles of 21 days, with three waves of follicle growth per cycle. The model contains 12 differential equations and 54 parameters. Focus in this paper is on development of the model, but also some simulation results are presented, showing that a set of equations and parameters is obtained that describes the system consistent with empirical knowledge. Even though the majority of the mechanisms that are included in the model are based on relations that in literature have only been described qualitatively (i.e. stimulation and inhibition), the output of the model is surprisingly well in line with empirical data. This model of the bovine estrous cycle could be used as a basis for more elaborate models with the ability to study effects of external manipulations and genetic differences. AMS MSC 2000: 92C42, 92C30, 90C31, 65L09

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Section: Progesteronementioning

confidence: 87%

Section: Follicle Developmentmentioning

confidence: 99%

Section: Corpus Luteummentioning

confidence: 99%

Section: Luteinizing Hormonementioning

confidence: 99%

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A simple mathematical model of the bovine estrous cycle: Follicle development and endocrine interactions

Bôer

Stötzel

Röblitz

et al. 2011

Journal of Theoretical Biology

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“…Blood concentration of progesterone is the major factor that affects LH pulse frequency in cyclic animals. Generally, lactating Holstein dairy cows tend to have lower blood concentrations of progesterone during the cycle than cyclic heifers (Sartori et al, 2004;Wolfenson et al, 2004). These lower progesterone concentrations tend to allow a subtle increase in LH pulse frequency and allows for prolonged growth of each dominant follicle rather than the faster atresia that occurs in cyclic heifers.…”

Section: Introductionmentioning

confidence: 99%

Parturition to resumption of ovarian cyclicity: comparative aspects of beef and dairy cows

Crowe

Diskin

Williams

2014

Animal

107

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There is a variable anoestrous period following parturition in the cow. Follicular growth generally resumes within 7 to 10 days in the majority of cows associated with a transient FSH rise that occurs within 3 to 5 days of parturition. Dairy cows that are not nutritionally stressed generally ovulate their first postpartum dominant follicle (~15 days), whereas beef suckler cows in good body condition normally have a mean of 3.2 ± 0.2 dominant follicles (~30 days) to first ovulation; moreover, beef cows in poor body condition have a mean of 10.6 ± 1.2 dominant follicles (~70 to 100 days) to first ovulation. The lack of ovulation of dominant follicles during the postpartum period is associated with infrequent LH pulses, with both maternal-offspring bonding and low body condition score (BCS) at calving being implicated as the predominant causes of delayed resumption of cyclicity in nursed beef cows. In dairy cows, the normal pattern of early resumption of ovulation may be delayed in high-yielding Holstein type cows generally owing to the effects of severe negative energy balance, dystocia, retained placental membranes and uterine infections. First ovulation, in both dairy and beef cows, is generally silent (i.e., no behavioural oestrus) and followed by a short inter-ovulatory interval (>70%). The key to optimizing the resumption of ovulation in both beef and dairy cows is appropriate pre-calving nutrition and management so that cows calve down in optimal body condition (BCS; 2.75 to 3.0) with postpartum body condition loss restricted to < 0.5 BCS units.

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Climate Resilient Livestock Production System in Tropical and Subtropical Countries

Hossain,

Rahman,

Karim

et al. 2023

Climate-Resilient Agriculture, Vol 1

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Follicular dynamics and concentrations of steroids and gonadotropins in lactating cows and nulliparous heifers

Cited by 122 publications

References 36 publications

A simple mathematical model of the bovine estrous cycle: Follicle development and endocrine interactions

A simple mathematical model of the bovine estrous cycle: Follicle development and endocrine interactions

Parturition to resumption of ovarian cyclicity: comparative aspects of beef and dairy cows

Climate Resilient Livestock Production System in Tropical and Subtropical Countries

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