Effect of the body condition of ewes on the secretion of LH and FSH and the pituitary response to gonadotrophin-releasing hormone

1989 ◽  
Vol 120 (3) ◽  
pp. 497-502 ◽  
Author(s):  
S. M. Rhind ◽  
S. McMillen ◽  
W. A. C. McKelvey ◽  
F. F. Rodriguez-Herrejon ◽  
A. S. McNeilly
Keyword(s):  
Body Condition ◽  
Luteal Phase ◽  
Body Condition Score ◽  
Pulse Amplitude ◽  
Ovarian Hormones ◽  
Pulse Frequency ◽  
Follicular Phase ◽  
High Body ◽  
Condition Score ◽  
Gonadotrophin Releasing Hormone

ABSTRACT The effects of body fat content (body condition) of ewes on hypothalamic activity and gonadotrophin-releasing hormone (GnRH) secretion and on pituitary sensitivity to GnRH were investigated using Scottish Blackface ewes. Two groups of 12 ewes were fed so that they achieved either a high body condition score (2·98, s.e.m. = 0·046; approximately 27% of empty body weight as fat) or a low body condition score (1·94, s.e.m. = 0·031; approximately 19% of empty body weight as fat) by 4 weeks before the period of study. Thereafter, they were differentially fed so that the difference in mean condition score was maintained. Oestrus was synchronized, and on day 11 of the subsequent cycle half of the ewes of each group were ovariectomized. On day 12, the remaining ewes were injected (i.m.) with 100 μg prostaglandin F2α analogue and ovariectomized 30 h later. Numbers of large ovarian follicles and corpora lutea present at ovariectomy were recorded. Blood samples were collected at 15-min intervals for 12 h on day 10 of the cycle (luteal phase) and at 10-min intervals from 24 to 30 h after prostaglandin injection (follicular phase). At days 2 and 7 after ovariectomy, samples were collected at 15-min intervals for 8 h and ewes were then injected with 10 μg GnRH and samples were collected for a further 3 h. Samples were assayed for LH and FSH. Ewes in high body condition had more more large follicles than ewes in low body condition during the luteal phase (15·3 vs 6·5; P < 0·05) and follicular phase (11·5 vs 7·0; NS) and a slightly higher mean ovulation rate (1·50 vs 1·20; NS). However, during the luteal and follicular phases of the cycle before ovariectomy there was no effect of condition score on mean LH or FSH concentrations or mean LH pulse frequency or pulse amplitude. Two days after ovariectomy, ewes of high body condition had a higher mean LH pulse frequency than ewes of low body condition (P < 0·05) and higher mean FSH concentrations (P < 0·05). Mean LH concentration and pulse amplitude were not affected. LH and FSH profiles were not affected by body condition on day 7. GnRH-induced increases in LH and FSH concentrations on days 2 and 7 were not affected by body condition. At day 7, but not day 2, ewes ovariectomized during the luteal phase of the cycle had a significantly (P < 0·05) greater GnRH-induced LH release compared with ewes ovariectomized during the follicular phase. It is concluded that body condition directly affects hypothalamic activity and GnRH secretion, but not pituitary sensitivity to GnRH, and that effects on reproductive performance are also mediated through changes in ovarian hormones or in hypothalamo-pituitary sensitivity to ovarian hormones. Journal of Endocrinology (1989) 120, 497–502

The effect of body condition and previous nutrition on the herbage intakes of ewes grazing autumn pastures at two sward heights

1994 ◽  
Vol 58 (2) ◽  
pp. 231-235 ◽  
Author(s):  
A. M. Sibbald ◽  
W. G. Kerr
Keyword(s):  
Body Condition ◽  
Body Condition Score ◽  
Day Treatment ◽  
Live Weight ◽  
Feeding Level ◽  
High Body ◽  
Sward Height ◽  
Herbage Intake ◽  
Condition Score ◽  
Grazing Period

AbstractTo examine the effects of body condition and previous nutrition on the herbage intake of ewes grazing swards of different heights in autumn, 96 Scottish Blackface X Border Leicester ewes with a wide range of body condition (score 1·75 to 3·50), were initially housed and given 50 g dry matter (DM) per kg metabolic live weight (M)0·75 per day (treatment L) or 95 g DM per kg M0·75 per day (treatment H) of a pelleted dried grass diet (11·6 MJ metabolizable energy per kg DM) for 6 weeks after weaning in July. The H ewes gained more live weight (9·0 v. 2·7 kg) and body condition score (0·39 v. 0·17) than the L ewes. Half the animals from each treatment were then allocated to each of two ryegrass pastures with a sward height of 5 cm (LS) or 10 cm (HS) for a further 6-week grazing period. During the grazing period there was no significant effect of indoor feeding level on herbage intake, but the L ewes gained more live weight (6·4 v. 5·0 kg) than the H ewes. On the HS, compared with the LS sward, mean herbage intakes were higher (70·0 v. 60·5 g DM per kg M0·75) as were gains in live weight and condition score (7·9 v. 3·4 kg; 0·18 v. 0·0). There were no interactions between the effects of sward height and previous feeding level on herbage intake. Ewes in low body condition (< 2·5) at the start of the grazing period ingested the same amount of herbage on both swards (70·3 g DM per kg M0·75) whereas ewes in high body condition (> 2·5) ingested more (67·0 v. 51·6 g DM per kg M0·75) on the HS compared with the LS sward. The responses of ewes in low and high body condition to different sward heights are discussed in relation to appetite drive and aspects of grazing behaviour.

Effects of body condition, food intake and temporary calf separation on the duration of the post-partum anoestrous period and associated LH, FSH and prolactin concentrations in beef cows

1987 ◽  
Vol 45 (3) ◽  
pp. 395-402 ◽  
Author(s):  
I. A. Wright ◽  
S. M. Rhind ◽  
A. J. F. Russel ◽  
T. K. Whyte ◽  
Alison J. McBean ◽  
...  
Keyword(s):  
Body Condition ◽  
Body Condition Score ◽  
Post Partum ◽  
Beef Cows ◽  
Pulse Frequency ◽  
Metabolizable Energy ◽  
Barley Straw ◽  
Blood Samples ◽  
Feeding Level ◽  
Condition Score

ABSTRACTAn experiment was conducted to examine factors affecting the length of the post-partum anoestrous period and associated effects on LH, FSH and prolactin. Forty-six cows (24 Hereford × Friesian and 22 Blue-Grey) ranging in body condition score at calving from 1·50 to 2·75 were used. They were individually fed chopped barley straw and concentrate at either 50 (low) or 91 (high) MJ metabolizable energy per day from calving. At 34 days post partum half the cows were separated from their calves for 48 h. The duration of the post-partum anoestrous period was estimated from progesterone concentrations in thrice weekly blood samples. Blood samples were collected every 20 min for 10 h periods immediately prior to calf separation, during the last 10 h of calf separation and 1 week later. All samples were analysed for LH, and every third sample was analysed for FSH and prolactin.There were no significant effects of genotype, feeding level or calf separation on the length of the post-partum anoestrous period. There was a negative association between body condition score at calving and the length of the anoestrous period, with each unit increase in body condition score reducing the anoestrous period by 43 (s.e. 20) days. There was some evidence that feeding level affected the number of thin cows (body condition score ≤2·25 at calving) which were still acyclic at the end of the experiment, but not the number of fat cows (body condition score ≥2·5 at calving).FSH levels were not affected by any of the factors examined. Prolactin concentrations were higher in fatter cows, in cows on the higher level of feeding and in Blue-Grey cows. Prolactin concentrations decreased during the period of calf separation. Genotype and feeding level had no effect on LH concentration or LH pulse frequency. LH pulse frequency was increased (P < 0·05) during the period of calf separation, but there was no effect 1 week later. There was a significant positive relationship between LH puise frequency and body condition score at calving in two of the three sampling periods.It is suggested that the effect of body condition on the duration of the post-partum anoestrous period i s mediated through effects on LH pulse frequency.

scholarly journals Short communication: Effects of serum obtained from dairy cows with low or high body condition score on in vitro embryo development

2013 ◽  
Vol 96 (3) ◽  
pp. 1668-1671 ◽  
Author(s):  
M. Oba ◽  
S. Miyashita ◽  
R. Nishii ◽  
M. Koiwa ◽  
H. Koyama ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Embryo Development ◽  
Body Condition ◽  
Short Communication ◽  
Body Condition Score ◽  
High Body ◽  
Communication Effects ◽  
Condition Score

Effect of graded doses of gonadotrophin-releasing hormone on serum LH concentrations in mares in various reproductive states: comparison with endogenously generated LH pulses

1986 ◽  
Vol 110 (1) ◽  
pp. 19-26 ◽  
Author(s):  
S. L. Alexander ◽  
C. H. G. Irvine
Keyword(s):  
Luteal Phase ◽  
Pulse Frequency ◽  
Follicular Phase ◽  
Hormone Release ◽  
Response Curves ◽  
Releasing Hormone ◽  
Serum Lh ◽  
Small Doses ◽  
Gonadotrophin Releasing Hormone ◽  
Log Linear

ABSTRACT Luteinizing hormone release induced by a range of small (3·3–33 μg) and large (300–500 μg) i.v. doses of gonadotrophin-releasing hormone (GnRH) was measured in acyclic (n = 4), luteal phase (n = 3) and follicular phase (n = 5) mares and compared with endogenously generated LH pulses in the same reproductive states. Extrapolation from log–linear dose–response curves showed that an LH pulse comparable to an endogenous one would be simulated by i.v. injection of 7·0 (n = 4) and 4·1 (n = 6) μg GnRH in luteal and follicular phase mares respectively; a much smaller dose than the 500 μg usually given clinically or experimentally. In acyclic mares (n = 4), LH pulses occurred too infrequently to be characterized. At small doses of GnRH the amount of LH released by the same dose was similar in all three reproductive states, although the steroid hormone milieu differed markedly. This implies that observed differences between states in mean (± s.e.m.) serum LH concentrations (0·7 ± 0·01, 1·2 ± 0·03 and 11·6 ± 0·33 (μg/l) in acyclic, luteal and follicular phase mares respectively) were produced by differences in GnRH pulse frequency and/or amplitude and not by steroid-mediated changes in pituitary response to GnRH. In acyclic, luteal and follicular phase mares, LH pulse frequency was: immeasurably low, 0·09 and 1·14 pulses/h respectively, which supports the important contribution of pulse frequency to determining mean LH concentration. The LH response to large doses of GnRH was significantly greater in the luteal than in the follicular phase, and was greater than the response to 33 μg in the luteal phase but not in the other two states. Thus, to a large but not to a small dose of GnRH, the pituitary appeared most responsive in the luteal phase. Therefore, in studies of the physiology of the hypothalamic-pituitary system, small doses of GnRH, which induce physiologically sized LH responses, may be preferred to large doses, which result in a level of stimulation to which the pituitary is never naturally exposed and to which it may respond in a non-physiological manner. J. Endocr. (1986) 110, 19–26

Effect of prepartum somatotropin injection in late pregnant Holstein heifers with high body condition score on metabolic parameters, resumption of ovulation and milk production

2013 ◽  
Vol 93 (2) ◽  
pp. 287-292 ◽  
Author(s):  
Diego Andres Velasco Acosta ◽  
Luiz Francisco Machado Pfeifer ◽  
Eduardo Schmitt ◽  
Augusto Schneider ◽  
Pedro Augusto Silva Silveira ◽  
...  
Keyword(s):  
Energy Balance ◽  
Milk Production ◽  
Body Condition ◽  
Body Condition Score ◽  
Post Partum ◽  
Dairy Heifers ◽  
Follicular Wave ◽  
High Body ◽  
Condition Score ◽  
Post Partum Period

Acosta, D. A. V., Pfeifer, L. F. M., Schmitt, E., Schneider, A., Silveira, P. A. S., Jacometo, C. B., Brauner, C. C., Rabassa, V. R., Corrêa, M. N. and Del Pino, F. A. B. 2013. Effect of prepartum somatotropin injection in late pregnant Holstein heifers with high body condition score on metabolic parameters, resumption of ovulation and milk production. Can. J. Anim. Sci. 93: 287–292. In the early post-partum period of dairy cows the duration and intensity of negative energy balance, the level of body condition score (BCS) loss and the milk yield are strongly associated with the timing of the first ovulation. The aim of this study was to determine the effect of pre-partum injections of somatotropin in dairy heifers with high BCS on the metabolism, resumption of ovarian activity and milk production. Holstein heifers (n=20) with high BCS, were divided randomly into two groups: somatotropin (n=10), which received two doses of somatotropin (500 mg) at −28 and −14 d from calving and Control (n=10), which received placebo. Blood samples were collected for evaluation of β-hydroxybutyrate (BHBA) and non-esterified fatty acids (NEFA) concentrations. Follicular development was also monitored via ultrasound. Somatotropin had no effect on plasma NEFA (P=0.35 and P=0.46) or BHBA (P=0.20 and P=0.44,) concentrations in the pre-partum and post-partum period, respectively. Milk production was not different between control (17.53±0.66 kg cow−1 d−1) and somatotropin groups (16.13±0.67 kg cow−1 d−1) (P=0.14). Pre-partum somatotropin administration did not affect (P=0.28) the time of the first post-partum ovulation. The proportion of cows ovulating the first post-partum follicular wave was not different between groups (P=0.49). In conclusion, pre-partum somatotropin treatment in dairy heifers with high body condition score seems not to have any effect on markers of energy balance, milk production or development of the first follicular wave in the early post-partum period.

Effect of epidermal growth factor on reproductive function of ewes

1985 ◽  
Vol 107 (3) ◽  
pp. 429-436 ◽  
Author(s):  
G. Shaw ◽  
G. I. Jorgensen ◽  
R. Tweedale ◽  
M. Tennison ◽  
M. J. Waters
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Luteal Phase ◽  
Reproductive Function ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Follicular Phase ◽  
Plasma Progesterone ◽  
Lh Surge ◽  
Epidermal Growth

ABSTRACT Adult Merino ewes were infused via the jugular vein with either saline (n = 5) or epidermal growth factor (EGF) (4·2 μg/kg per h, n = 6) for 24 h in either the luteal phase or the follicular phase of the oestrous cycle and reproductive function was examined. Infusion of EGF during the luteal phase caused no detectable change in plasma progesterone or prolactin concentrations over a 7-day period compared with the controls. Infusion of EGF during the follicular phase suppressed the oestrous rise in plasma oestradiol. Luteinizing hormone pulse amplitude was increased and pulse frequency was decreased by the end of the infusion. All control ewes had a pro-oestrous LH surge and mated, but the LH surge and oestrus were prevented by EGF infusion. Nevertheless, plasma progesterone levels rose subsequently in the EGF-infused ewes in parallel with the control ewes, suggesting that the preovulatory follicle had luteinized. Both LH and FSH rose over the 7 days after EGF infusion to levels similar to those in ovariectomized ewes. Thus EGF appears to inhibit follicular oestradiol production, although it does not affect luteal progesterone production or follicular luteinization. We suggest that the alteration in gonadotrophin secretion patterns results from a disturbance of feedback mechanisms between the ovary and the hypothalamopituitary axis, although a direct effect in the brain or the pituitary gland cannot yet be excluded. J. Endocr. (1985) 107, 429–436

scholarly journals Effects of hyperandrogenemia and increased adiposity on reproductive and metabolic parameters in young adult female monkeys

2014 ◽  
Vol 306 (11) ◽  
pp. E1292-E1304 ◽  
Author(s):  
W. K. McGee ◽  
C. V. Bishop ◽  
C. R. Pohl ◽  
R. J. Chang ◽  
J. C. Marshall ◽  
...  
Keyword(s):  
Luteal Phase ◽  
Polycystic Ovary ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Follicular Phase ◽  
Antral Follicles ◽  
Reproductive Axis ◽  
Early Follicular Phase ◽  
Follicular Size ◽  
Cholesterol Control

Many patients with hyperandrogenemia are overweight or obese, which exacerbates morbidities associated with polycystic ovary syndrome (PCOS). To examine the ability of testosterone (T) to generate PCOS-like symptoms, monkeys received T or cholesterol (control) implants ( n = 6/group) beginning prepubertally. As previously reported, T-treated animals had increased neuroendocrine drive to the reproductive axis [increased luteinizing hormone (LH) pulse frequency] at 5 yr, without remarkable changes in ovarian or metabolic features. To examine the combined effects of T and obesity, at 5.5 yr (human equivalent age: 17 yr), monkeys were placed on a high-calorie, high-fat diet typical of Western cultures [Western style diet (WSD)], which increased body fat from <2% (pre-WSD) to 15–19% (14 mo WSD). By 6 mo on WSD, LH pulse frequency in the controls increased to that of T-treated animals, whereas LH pulse amplitude decreased in both groups and remained low. The numbers of antral follicles present during the early follicular phase increased in both groups on the WSD, but maximal follicular size decreased by 50%. During the late follicular phase, T-treated females had greater numbers of small antral follicles than controls. T-treated monkeys also had lower progesterone during the luteal phase of the menstrual cycle. Although fasting insulin did not vary between groups, T-treated animals had decreased insulin sensitivity after 1 yr on WSD. Thus, while WSD consumption alone led to some features characteristic of PCOS, T + WSD caused a more severe phenotype with regard to insulin insensitivity, increased numbers of antral follicles at midcycle, and decreased circulating luteal phase progesterone levels.

Pulsatile secretion of inhibin, oestradiol and androstenedione by the ovary of the sheep during the oestrous cycle

1990 ◽  
Vol 126 (3) ◽  
pp. 385-393 ◽  
Author(s):  
B. K. Campbell ◽  
G. E. Mann ◽  
A. S. McNeilly ◽  
D. T. Baird
Keyword(s):  
Luteal Phase ◽  
Venous Blood ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Blood Samples ◽  
Early Follicular Phase ◽  
Lh Secretion ◽  
Late Follicular Phase

ABSTRACT The pattern of pulsatile secretion of inhibin, oestradiol and androstenedione by the ovary at different stages of the oestrous cycle in sheep was studied in five Finn–Merino ewes in which the left ovary had been autotransplanted to the neck. The ewes had jugular venous blood samples collected at 4-hourly intervals from 42 h before the induction of luteolysis by i.m. injection of cloprostenol (100 μg) on day 10 of the oestrous cycle, until day 3 of the following cycle. There were five periods of intensive blood sampling, when both ovarian and jugular venous blood samples were collected, as follows: (a) mid-luteal phase, before the second injection of cloprostenol on day 10 (15-min intervals for 6 h); (b) early follicular phase, 24 h after the second injection of cloprostenol (10-min intervals for 4 h); (c) late follicular phase, 48 h after the second injection of cloprostenol (10-min intervals for 4 h); (d) after the LH surge on day 1 of the cycle, 76 h after the second injection of cloprostenol (10-min intervals for 4 h); (e) early luteal phase on day 3 of the cycle, 120 h after the second injection of cloprostenol (10-min intervals for 3 h). Plasma was collected and the samples assayed for LH, FSH, progesterone, oestradiol, androstenedione and inhibin. The ovarian secretion rates for oestradiol, androstenedione and inhibin were calculated. All ewes responded normally to the luteolytic dose of cloprostenol with the preovulatory surge of LH occurring within 56·4±1·6 h (mean ± s.e.m.) followed by the establishment of a normal luteal phase. The pulse frequency of LH, oestradiol and androstenedione increased in the transition from the luteal to the follicular phase (P<0·01). On day 1 of the cycle LH secretion consisted of low-amplitude high-frequency pulses (1·0±0·1 pulse/h) to which androstenedione, but not oestradiol, responded. On day 3 of the cycle LH secretion was similar to that on day 1 but both androstenedione and oestradiol secretion were pulsatile in response to LH, indicating the presence of oestrogenic follicles. The stage of the cycle had no significant effects on LH pulse amplitude and nadir but the ovarian secretory response to LH stimulation did vary with the stage of the cycle. Prolactin pulse frequency, amplitude and nadir were higher (P<0·05) during the follicular phase than the luteal phase. Prolactin pulse frequency was depressed (P<0·05) on day 1 of the cycle but increased to follicular phase levels on day 3. Prolactin pulse frequency was significantly correlated to oestradiol pulse frequency (r = 0·54; P<0·01). During the luteal phase there were insufficient oestradiol pulses to obtain an estimate of pulse amplitude and nadir but both these parameters reached their highest level during the late follicular phase, fell to negligible levels on day 1 and increased to early follicular phase levels on day 3. Androstenedione pulse amplitude and nadir exhibited similar but less marked variation. Inhibin secretion was episodic at all stages of the cycle examined but did not exhibit significant variation with stage of cycle in any of the parameters of episodic secretion measured. Inhibin pulses were not related to either LH or prolactin at any stage of the cycle. FSH secretion was not detectably pulsatile but jugular venous concentrations of FSH at each stage of the oestrous cycle were negatively correlated with mean oestradiol (r= −0·52; P<0·01 but not inhibin secretion (r = 0·19). We conclude that (i) LH secretion is pulsatile at all stages of the oestrous cycle but the steroidogenic responses of the ovary varies with the stage of the cycle, reflecting changes in characteristics of the follicle population, (ii) ovarian inhibin secretion is episodic and displays little change with the stage of the oestrous cycle and (iii) episodic inhibin secretion is not related to either pulses of LH or prolactin. The aetiology of these inhibin pulses therefore remains unknown. Journal of Endocrinology (1990) 126, 385–393

Circulating concentrations of LH and FSH and pituitary responsiveness to GnRH in intact and ovariectomized suckled beef cows in two levels of body condition

1990 ◽  
Vol 51 (1) ◽  
pp. 93-101 ◽  
Author(s):  
I. A. Wright ◽  
S. M. Rhind ◽  
T. K. Whyte ◽  
A. J. Smith ◽  
S. R. McMillen ◽  
...  
Keyword(s):  
Body Condition ◽  
Body Condition Score ◽  
Post Partum ◽  
Live Weight ◽  
High Sensitivity ◽  
Fold Increase ◽  
Beef Cows ◽  
Pulse Frequency ◽  
Condition Score ◽  
Physiological Dose

ABSTRACTThe effect of body condition on hypothalamic and pituitary function in post-partum suckled beef cows was studied. Thirty-eight Blue-Grey cows were calved at a body condition score of either 2·35 (L) or 2·80 (H), fed to maintain live weight and body condition thereafter and ovariectomized at either 5 or 9 weeks post partum. The H cows had higher LH pulse frequencies before ovariectomy (0·36 v. 0·28 pulses per h; P < 0·05) and 15 days after ovariectomy (0·86 v. 0·72 pulses per h; P < 0·01), indicating a direct effect of body condition on GnRH release from the hypothalamus. Body condition had no effect on the ability of the pituitary to release LH in response to a physiological dose (2·5 u.g) of GnRH in entire or ovariectomized cows at 5 or 9 weeks post partum. The magnitude of the increase in circulating levels of LH following GnRH injection was greater at 9 weeks compared with 5 weeks post partum (2·23 v. 1·73 u.g/1; P < 0·001) in entire cows, but there was no difference between 5 and 9 weeks in ovariectomized cows. Following ovariectomy there was a 2·5-fold increase in LH pulse frequency within 15 days and LH pulse frequency approached 1 pulse per h in all treatments groups. It is concluded that both the hypothalamus and the pituitary are capable of functioning normally by 5 weeks post partum in suckled beef cows, that the pulsatile release of GnRH from the hypothalamus is inhibited, possibly due to a very high sensitivity to oestradiol, and that the sensitivity of the pituitary to the negative feedback effect of oestradiol may decrease with time post partum.

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