Nutrient effects on ovulation rate, ovarian function and the secretion of gonadotrophic and metabolic hormones in sheep

In adult ewes, we tested whether ovarian function, including the response to short-term supplementation, was affected by the nutrition of their mothers during the pre-/post-natal period. A 2×2 factorial design was used with nutrition in early life (low or high) and a 6-day supplement (with or without) as factors. All ewes received three prostaglandin (PG) injections 7 days apart, and the supplement (lupin grain) was fed for 6 days from 2 days after the second until the third PG injection. We measured reproductive and metabolic hormones, studied follicle dynamics (ultrasonography), and evaluated granulosa cell numbers, aromatase activity and oestradiol (E2) concentrations in follicular fluid in healthy follicles at days 3 and 7 of supplementation. Ovulation rate was increased by 25% by exposure to high pre-/post-natal nutrition (1.5 vs 1.2; P<0.05), in association with a small decrease in FSH concentrations (P=0.06) and a small increase in insulin concentrations (P=0.07). The number of healthy antral follicles was not affected. Acute supplementation increased the number of granulosa cells (3.7±0.2 vs 3.0±0.2 million; P<0.05) in the largest follicle, and the circulating concentrations of E2 (4.6±0.3 vs 3.9±0.3 pmol/l; P<0.05) and glucose (3.4±0.03 vs 3.3±0.03 mmol/l; P<0.01). Both early life nutrition and acute supplementation appear to affect ovulation rate through changes in glucose–insulin homoeostasis that alter follicular responsiveness to FSH and therefore E2–FSH balance.

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The use of a ‘first-wave’ model to study the effect of nutrition on ovarian follicular dynamics and ovulation rate in the sheep

Reproduction ◽

10.1530/rep-10-0196 ◽

2010 ◽

Vol 140 (6) ◽

pp. 865-874 ◽

Cited By ~ 27

Author(s):

C Viñoles ◽

B Paganoni ◽

K M M Glover ◽

J T B Milton ◽

D Blache ◽

...

Keyword(s):

Body Condition ◽

Wave Model ◽

Ovulation Rate ◽

Short Term ◽

Metabolic Hormones ◽

Follicular Waves ◽

Follicular Wave ◽

The Third ◽

High Concentrations ◽

Follicular Dynamics

We have developed an experimental model in which groups of ewes are simultaneously experiencing the first ovarian follicular wave of their oestrous cycle. We used this ‘first-wave model’ in a 2×2 factorial experiment (ten ewes per group) to study the effect of body condition (BC) and a short-term supplement on follicular dynamics and ovulation rate. The ‘first-wave’ was established by giving ewes three injections of prostaglandin (PG), 7 days apart. The 6-day supplement (lupin grain) began 2 days after the second PG injection and continued until the third. Follicles were studied by ultrasound, and blood was sampled to measure glucose and hormones. The supplement increased (P<0.01) the concentrations of glucose, insulin and leptin, decreased FSH concentrations (P<0.01) and tended to increase oestradiol concentrations (P=0.06). The supplement tended to increase the number of 3 mm follicles (P=0.06). Compared with low-BC ewes, high-BC ewes had more follicular waves (P<0.05), higher concentrations of insulin, leptin and IGF1 (P<0.05) and tended to have higher FSH concentrations (P=0.09). Leptin and insulin concentrations remained high until the end of supplementation in high-BC ewes, whereas they decreased after the third day of supplementation in low-BC ewes. In conclusion, high concentrations of metabolic hormones in fat ewes are associated with the development of more follicular waves. When a supplement is superimposed on this situation, changes in glucose and metabolic hormones allow more follicles to be selected to ovulate.

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Plasma leptin concentration and its interrelation with some blood metabolites, metabolic hormones and the resumption of cyclic ovarian function in postpartum dairy cows supplemented with monensin or inert fat in feed

BSAP Occasional Publication ◽

10.1017/s0263967x00034005 ◽

2001 ◽

Vol 26 (2) ◽

pp. 405-409 ◽

Cited By ~ 3

Author(s):

Gy. Huszenicza ◽

M. Kulcsar ◽

J. A. Nikolic ◽

J. Schmidt ◽

P. Korodi ◽

...

Keyword(s):

Dairy Cows ◽

Low Dose ◽

Ovarian Function ◽

Metabolic Hormones ◽

Delayed Onset ◽

Wide Range ◽

Significant Difference ◽

Minimal Concentration ◽

Plasma Leptin ◽

Ovarian Cyclicity

AbstractThe postpartum changes in plasma leptin levels of dairy cows ovulated within 35 days after calving were compared to of those with delayed onset of cyclicity in two experiments. The cows were sampled for leptin, insulin, IGF-1, thyroid hormones (T4, T3, rT3), Cortisol and also for some metabolites (glucose, NEFA, BHB and TCH) on day 1-3 after calving and again four times 7 days apart (Exp. 1), or in weeks 1, 2, 3, 5 and 10 postpartum (Exp. 2). In Exp. 1 also the standard low dose ACTH-induced Cortisol response and TRH-stimulated T4/T3 responses were determined on days 1-3 and 28-35. In cows of Exp. 1 the leptin level varied within a wide range with a mean of about 4 ng/ml HE in the first samples. Up to week 5 it remained unchanged in cows ovulated within day 35 but reduced in those with delayed onset of cyclicity, resulting in significant difference between the two group means.In cows of Exp. 2 the week 1 leptin levels were lower and less variable than that of Exp. 1. In weeks 2 and 3 a slightly increasing tendency of leptin pattern was seen in cows resuming their ovarian cyclicity within 35 days whereas in those with delayed onset of cyclicity the leptin level remained unchanged. Up to week 5 this tendency resulted in exactly the same leptin values as seen in Exp. 1 with significant differences between the group means in both of the weeks 5 and 10. It was concluded that the plasma leptin concentration in postpartum dairy cows may interfere with resumption of cyclic ovarian function, but its influence may be only permissive (e.g. a minimal concentration above a supposed threshold seems to be the prerequisite of the onset of cyclicity)

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Factors affecting folliculogenesis in ruminants

Animal Science ◽

10.1017/s1357729800050293 ◽

1999 ◽

Vol 68 (2) ◽

pp. 257-284 ◽

Cited By ~ 65

Author(s):

R. Webb ◽

R. G. Gosden ◽

E. E. Telfer ◽

R. M. Moor

Keyword(s):

New Technologies ◽

Ovarian Function ◽

Major Gene ◽

Follicular Development ◽

Oocyte Quality ◽

Ovulation Rate ◽

Follicular Growth ◽

Stages Of Development ◽

Hormone Production ◽

Factors Affecting

AbstractThis review addresses the reasons for the lack of progress in the control of superovulation and highlights the importance of understanding the mechanisms underlying follicular development. The present inability to provide large numbers of viable embryos from selected females still restricts genetic improvement, whilst variability in ovarian response to hormones limit the present capacity for increasing reproductive efficiency.Females are born with a large store of eggs which rapidly declines as puberty approaches. If these oocytes are normal then there is scope for increasing the reproductive potential of selected females. Oocytes must reach a certain size before they can complete all stages of development and the final changes that occur late in follicular development. It is likely that oocytes that do not produce specific factors at precise stages of development will not be viable. Hence, it is important to characterize oocyte secreted factors since there are potential indicators of oocyte quality.The mechanisms that determine ovulation rate have still not been fully elucidated. Indeed follicular atresia, the process whereby follicles regress, is still not known. A better understanding of these processes should prove pivotal for the synchronization of follicular growth, for more precise oestrous synchronization and improved superovulatory response.Nutrition can influence a whole range of reproductive parameters however, the pathways through which nutrition acts have not been fully elucidated. Metabolic hormones, particularly insulin and IGFs, appear to interact with gonadotrophins at the level of the gonads. Certainly gonadotropins provide the primary drive for the growth of follicles in the later stages of development and both insulin and IGF-1, possibly IGF-2, synergize with gonadotrophins to stimulate cell proliferation and hormone production. More research is required to determine the effects of other growth factors and their interaction with gonadotropins.There is evidence, particularly from studies with rodents, that steroids can also modulate follicular growth and development, although information is very limited for ruminants. There may be a rôle for oestrogens in synchronizing follicular waves, to aid in oestrous synchronization regimes and for removing the dominant follicle to achieve improved superovulatory responses. However more information is required to determine whether these are feasible approaches.Heritability for litter size is higher in sheep than in cattle. Exogenous gonadotropins are a commercially ineffective means of inducing twinning in sheep and cattle. Although there are differences in circulating gonadotropin concentrations, the mechanism(s) responsible for the high ovulation appear to reside essentially within the ovaries. The locus of the Booroola gene, a major gene for ovulation rate, has been established but not specifically identified. However sheep possessing major genes do provide extremely valuable models for investigating the mechanisms controlling ovulation rate, including a direct contrast to mono-ovulatory species such as cattle.In conclusion, the relationship between oocyte quality, in both healthy follicles and those follicles destined for atresia, must be resolved before the future potential for increasing embryo yield can be predicted. In addition, a greater understanding of the factors affecting folliculogenesis in ruminants should ensure that the full benefits ensuing from the precise control of ovarian function are achieved. The improved use of artificial insemination and embryo transfer that would ensue from a greater understanding of the processes of folliculo genesis, coupled with the new technologies of genome and linkage mapping, should ensure a more rapid rate of genetic gain.

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Female Mice Haploinsufficient for an Inactivated Androgen Receptor (AR) Exhibit Age-Dependent Defects That Resemble the AR Null Phenotype of Dysfunctional Late Follicle Development, Ovulation, and Fertility

Endocrinology ◽

10.1210/en.2007-0248 ◽

2007 ◽

Vol 148 (8) ◽

pp. 3674-3684 ◽

Cited By ~ 90

Author(s):

K. A. Walters ◽

C. M. Allan ◽

M. Jimenez ◽

P. R. Lim ◽

R. A. Davey ◽

...

Keyword(s):

Androgen Receptor ◽

Ovarian Function ◽

Gene Dosage ◽

Early Embryo ◽

Ovulation Rate ◽

Corpora Lutea ◽

Cell Stage ◽

Gene Dosage Effect ◽

Female Mice ◽

Age Dependent

The role of classical genomic androgen receptor (AR) mediated actions in female reproductive physiology remains unclear. Female mice homozygous for an in-frame deletion of exon 3 of the Ar (AR−/−) were subfertile, exhibiting delayed production of their first litter (AR+/+ = 22 d vs. AR−/− = 61 d, P < 0.05) and producing 60% fewer pups/litter (AR+/+: 8.1 ± 0.4 vs. AR−/−: 3.2 ± 0.9, P < 0.01). Heterozygous females (AR+/−) exhibited an age-dependent 55% reduction (P < 0.01) in pups per litter, evident from 6 months of age (P < 0.05), compared with AR+/+, indicating a significant gene dosage effect on female fertility. Ovulation was defective with a significant reduction in corpora lutea numbers (48–79%, P < 0.01) in 10- to 12- and 26-wk-old AR+/− and AR−/− females and a 57% reduction in oocytes recovered from naturally mated AR−/− females (AR+/+: 9.8 ± 1.0 vs. AR−/−: 4.2 ± 1.2, P < 0.01); however, early embryo development to the two-cell stage was unaltered. The delay in first litter, reduction in natural ovulation rate, and aromatase expression in AR+/− and AR−/− ovaries, coupled with the restored ovulation rate by gonadotropin hyperstimulation in AR−/− females, suggest aberrant gonadotropin regulation. A 2.7-fold increase (AR+/+: 35.4 ± 13.4 vs. AR−/−: 93.9 ± 6.1, P < 0.01) in morphologically unhealthy antral follicles demonstrated deficiencies in late follicular development, although growing follicle populations and growth rates were unaltered. This novel model reveals that classical genomic AR action is critical for normal ovarian function, although not for follicle depletion and that haploinsufficiency for an inactivated AR may contribute to a premature reduction in female fecundity.

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Ovulation rate and the concentrations of gonadotrophic and metabolic hormones in ewes fed lupin grain

Reproduction ◽

10.1530/jrf.0.1030137 ◽

1995 ◽

Vol 103 (1) ◽

pp. 137-145 ◽

Cited By ~ 97

Author(s):

J. A. Downing ◽

J. Joss ◽

P. Connell ◽

R. J. Scaramuzzi

Keyword(s):

Ovulation Rate ◽

Metabolic Hormones

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Effect of active immunization of heifers against inhibin on plasma FSH concentrations, ovarian follicular development and ovulation rate

Journal of Endocrinology ◽

10.1677/joe.0.1340011 ◽

1992 ◽

Vol 134 (1) ◽

pp. 11-18 ◽

Cited By ~ 30

Author(s):

R. G. Glencross ◽

E. C. L. Bleach ◽

B. J. McLeod ◽

A. J. Beard ◽

P. G. Knight

Keyword(s):

Synthetic Peptide ◽

Ovarian Function ◽

Statistical Significance ◽

Follicular Development ◽

Ovarian Response ◽

Active Immunization ◽

Ovulation Rate ◽

Corpora Lutea ◽

Α Subunit ◽

Ovarian Follicular Development

ABSTRACT To study the effects of immunoneutralization of endogenous inhibin on gonadotrophin secretion and ovarian function, prepubertal heifers (n = 6) were actively immunized against a synthetic peptide replica of the N-terminal sequence of bovine inhibin α subunit bIα(1–29)Tyr30) coupled to ovalbumin. In contrast to ovalbumin-immunized controls (n=6), bIα(1–29)Tyr30-immunized heifers had detectable inhibin antibody titres (% binding to 125I-labelled bovine inhibin at 1:2000 dilution of plasma) of 17 ± 3% (s.e.m.) at puberty, rising to 31 ± 5% by the end of the study period 7 months later. Neither age (immunized: 295 ± 8 days; controls: 300 ± 5 days) nor body weight (immunized: 254 ± 13 kg; controls 251 ± 9 kg) at onset of puberty differed between groups. Although the difference did not reach statistical significance, mean plasma FSH concentrations recorded in inhibin-immunized heifers remained 35–40% higher than in controls throughout the 12-week period leading up to puberty (P = 0·14) and during nine successive oestrous cycles studied after puberty (P=0·10). Plasma LH concentrations did not differ between groups at any time during the study. Inhibin immunization had no effect on oestrous cycle length (immunized: 19·8±0·5 days; controls: 19·9±0·5 days). However, in comparison with controls, inhibinimmunized heifers had more medium sized (≥0·5 to <1 cm diameter) follicles during both the preovulatory (95%, P<0·001) and post-ovulatory (110%, P < 0·05 waves of follicular growth and more large (>1 cm diameter) follicles during the preovulatory wave (49%, P<0·05). In addition, the number of corpora lutea observed during the post-ovulatory phase of each cycle was significantly greater in the inhibin-immunized group (43%, P<0·01), as was the recorded incidence of cycles with multiple ovulations (19/56 in the inhibin-immunized group compared with 0/54 in controls; P<0·001). All six inhibinimmunized heifers had at least one cycle with multiple ovulation whereas none of the control heifers did so. These results support the conclusion that immunoneutralization of endogenous inhibin using a synthetic peptide-based vaccine can enhance ovarian follicular development and ovulation rate in heifers. Whether this ovarian response is dependent upon the expected increase in secretion of FSH remains to be established. Journal of Endocrinology (1992) 134, 11–18

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P884 Improvement of the ovarian function, follicular growth and ovulation rate using Metformin in patients with polycystic ovarian syndrome

International Journal of Gynecology & Obstetrics ◽

10.1016/s0020-7292(09)62372-9 ◽

2009 ◽

Vol 107 ◽

pp. S663-S663

Author(s):

E. Trajkovska ◽

G. Dimitrov ◽

E. Dzikova ◽

I. Andonova ◽

L. Hodza

Keyword(s):

Polycystic Ovarian Syndrome ◽

Ovarian Function ◽

Ovulation Rate ◽

Follicular Growth ◽

Ovarian Syndrome

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Effects of active immunization against growth differentiation factor 9 and/or bone morphogenetic protein 15 on ovarian function in cattle

Reproduction ◽

10.1530/rep-09-0009 ◽

2009 ◽

Vol 138 (1) ◽

pp. 107-114 ◽

Cited By ~ 37

Author(s):

Jennifer L Juengel ◽

Norma L Hudson ◽

Martin Berg ◽

Keith Hamel ◽

Peter Smith ◽

...

Keyword(s):

Bone Morphogenetic Protein ◽

Ovarian Function ◽

Follicular Development ◽

Active Immunization ◽

Ovulation Rate ◽

Differentiation Factor ◽

Morphogenetic Protein ◽

Growth Differentiation Factor 9 ◽

Bone Morphogenetic Protein 15 ◽

Ovarian Follicular Development

Growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are essential for ovarian follicular growth in sheep, whereas only GDF9 is essential in mice suggesting that the roles of these oocyte-derived growth factors differ among species. At present, however, there is only limited information on the action of BMP15 and GDF9 in other species. Thus, the aim of this experiment was to determine the effect of neutralizing GDF9 and/or BMP15in vivoon ovarian follicular development and ovulation rate in cattle through active immunization using the mature regions of the proteins or peptides from the N-terminal area of mature regions. Immunization with the BMP15 peptide, with or without GDF9 peptide, significantly altered (increased or decreased) ovulation rate. In some animals, there were no functional corpora lutea (CL), whereas in others up to four CL were observed. From morphometric examination of the ovaries, immunization with GDF9 and/or BMP15 reduced the level of ovarian follicular development as assessed by a reduced proportion of the ovarian section occupied by antral follicles. In addition, immunization against GDF9 and/or BMP15 peptides reduced follicular size to <25% of that in the controls. In conclusion, immunization against GDF9 and BMP15, alone or together, altered follicular development and ovulation rate in cattle. Thus, as has been observed in sheep, both GDF9 and BMP15 appear to be key regulators of normal follicular development and ovulation rate in cattle.

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Milk progesterone profiles, blood metabolites, metabolic hormones and pregnancy rates in Awassi ewes treated by gestagen + eCG at the early breeding season

Veterinární Medicína ◽

10.17221/20/2009-vetmed ◽

2009 ◽

Vol 54 (No. 11) ◽

pp. 507-516 ◽

Cited By ~ 3

Author(s):

A. Marton ◽

V. Faigl ◽

M. Kerestes ◽

M. Kulcsar ◽

S. Nagy ◽

...

Keyword(s):

Ovarian Function ◽

Transition Period ◽

Late Summer ◽

Ovarian Response ◽

Fixed Time ◽

Conception Rate ◽

Metabolic Hormones ◽

Igf I ◽

Pre Treatment ◽

Almost All

The ovarian response to a standard chronogest + eCG treatment with plasma levels of insulin, insulin-like growth factor-I (IGF-I), thyroids, non-esterified fatty acids (NEFA), OH-butyrate (BHB) and urea-N (PUN) was studied in lactating Awassi ewes (n = 105) during the late-summer – early autumn transition period. The ewes were inseminated with diluted fresh semen after gestagen removal, and mated thereafter; 26 of them conceived at the fixed-time AI (fix AI; conception rate is calculated from lambing dates). Ovarian function was monitored by milk progesterone (P4) profiles. Before synchronization, the ovary was still acyclic in 33 and already cyclic in 72 ewes. Twenty-nine and 43 of the cyclic animals were in the follicular and luteal phases, respectively. After gestagen removal almost all (n = 104) ewes ovulated, although at AI elevated P4 levels related to the presence of partially luteinized follicles, and short-lived CL-s were observed in 10 and five animals (none of them re-conceived at the fixed time AI). Cycling ewes showed higher insulin and IGF-I levels than the acyclic animals, and those who had not conceived had higher PUN than the pregnant ones. The other metabolic parameters did not differ. Neither conception rate, nor the ovarian response was influenced by the pre-treatment.

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