Overview of the response of anoestrous ewes to the ram effect

2004 ◽  
Vol 16 (4) ◽  
pp. 479 ◽  
Author(s):  
R. Ungerfeld ◽  
M. Forsberg ◽  
E. Rubianes
Keyword(s):  
Post Partum ◽  
Ovarian Response ◽  
Short Length ◽  
Present Review ◽  
Response Patterns ◽  
Endocrine Response ◽  
Lh Pulsatility ◽  
Reproductive Response ◽  
Endocrine Parameters ◽  
Ram Effect

The present review summarises knowledge of the reproductive response of anoestrous ewes to the introduction of rams – in other words, the ram effect. The ovarian and endocrine response, the factors that determine whether ewes will respond or not (associated with both the stimulus and the receptivity of the ewes) and some aspects of practical management are discussed. Information on the use of the ram effect to stimulate post-partum, prepubertal and cyclic ewes is also given. New insights are provided on ovarian response patterns, including recently collected information on luteal responses. The existence of delayed ovulation (5–7 days after the introduction of the rams) followed by luteal phases of normal or short length, luteal cysts and luteinised follicles is reported after scanning the ovaries with ultrasound. Endocrine parameters for depth of anoestrus, such as LH pulsatility and FSH concentrations, and how the concentrations of these hormones should be considered are discussed. Particular attention is paid to the observation of spontaneous, higher LH pulsatility and higher FSH concentrations in anoestrous ewes that respond to rams with luteal phases than in those that fail to respond. The use of progestogen priming and single progestogen administration and the possible advantages for synchronisation of oestrus are also discussed. Other factors that should be considered before the ram effect is applied, such as the strength of the stimulus and some practical considerations, are also included.

The pattern of LH secretion and the ovarian response to the ‘ram effect’ in the anoestrous ewe is influenced by body condition but not by short-term nutritional supplementation

2014 ◽  
Vol 26 (8) ◽  
pp. 1154 ◽  
Author(s):  
R. J. Scaramuzzi ◽  
L. Oujagir ◽  
J-B. Menassol ◽  
S. Freret ◽  
A. Piezel ◽  
...  
Keyword(s):  
Body Condition ◽  
Ovarian Response ◽  
Nutritional Supplementation ◽  
Short Term ◽  
Blood Concentrations ◽  
Lh Surge ◽  
Lh Pulsatility ◽  
Lower Glucose ◽  
Good Nutrition ◽  
Ram Effect

In sheep, the ‘ram effect’ induces out-of-season fertility and good nutrition increases prolificacy. This experiment determined if fatness or short-term nutritional supplementation modified the response to the ‘ram effect’. A group of 48 Île-de-France ewes were fed diets that produced groups with body-condition scores (BCS) of >3.0 and <2.0. Within each BCS group animals were supplemented daily with 500 g of lupins from Day –5 to Day 0 (ram introduction) resulting in four groups: low BCS, supplemented (n = 7) and non-supplemented (n = 8) and high BCS, supplemented (n = 12) and non-supplemented (n = 11). The blood concentrations of glucose and insulin and the LH response to gonadotrophin-releasing hormone (GnRH) were determined. After the ‘ram effect’ the pattern of LH pulsatility, the LH surge and ovarian responses were analysed. Low BCS ewes had lower glucose and insulin (P < 0.001) and supplementation increased both (P ≤ 0.001). The increase in LH induced by GnRH was reduced in low BCS ewes (P = 0.015) but it was not affected by supplementation. Similarly, LH pulsatility was reduced in low BCS ewes (P < 0.05). The LH surge and ovarian cyclicity were not affected but the follow-up cycle was delayed (P = 0.034) and progesterone was reduced (P = 0.029) in low BCS ewes. There was an effect of BCS on ovulation rate (P < 0.05). These results show that the BCS can modify the response to the ‘ram effect’ and that supplementation has little effect on this response.

Comparison of reproductive responses after PGF2α and GnRH-PGF2α oestrous synchronisation schemes in Holstein cows

2001 ◽  
Vol 26 (2) ◽  
pp. 467-470
Author(s):  
J.F. Cox ◽  
F. Saravia ◽  
O. Torrealba ◽  
A. Zavala ◽  
A. Lobos
Keyword(s):  
Dairy Cows ◽  
Corpus Luteum ◽  
Detection Efficiency ◽  
Post Partum ◽  
Conception Rate ◽  
Milk Samples ◽  
Reproductive Response ◽  
Holstein Friesian ◽  
Breeding Schemes ◽  
Friesian Cows

AbstractControlled breeding schemes for oestrous detection constitutes a proactive technical response that balances the infrastructural requirement for a profitable dairy operation and the demands for optimal animal performance. The present study compared (a) the reproductive response of a treatment based on a short vs longer-acting PGF2α analogue (tiaprost vs luprostiol), and (b) the reproductive response after a treatment of GnRH-PGF2α vs PGF2α alone for synchronizing dairy cows. Holstein-Friesian cows averaging 9000 kg milk/lactation and fed according to their requirements were used in the study. Cows were cyclic, at least 60 days post partum and were clinically sound before being considered for the experiments. In Experiment 1, animals were synchronised using an i.m. injection of either 15 mg of luprostiol or 0.75 mg of tiaprost, based on ultrasonic diagnosis of a corpus luteum. Animals were inseminated at observed oestrus. In Experiment 2, cows were synchronised, at random, by either an injection of 10pg ofbuserelin (day 0) followed by 0.75 mg of tiaprost at day 7 (GnRH-PGF2α) orjust 0.75 mg of tiaprost (PGF2α). For both treatments only cows with an ultrasonically detected corpus luteum were treated. Animals were inseminated at oestrus. At the time of treatment and again 3 days later, milk samples were collected and assayed for progesterone by RIA. Cows with progesterone concentrations >1 ng/ml were considered to have corpus luteum. Luteolysis was considered to have occurred when concentrations of progesterone were > 1 ng/ml at day 0 and <0.8 ng/ml at day 3. In Experiment 1, both analogues gave similar results in terms of induced luteolysis [luprostiol: 36/39 (92.3%) vs tiaprost: 36/41 (87.8%)], oestrous detection efficiency [luprostiol: 26/36 (72.2%) vs tiaprost: 30/36 (83.3%], oestrous distribution [day 2, 3 and 4, respectively: luprostiol: 26.9%, 50.0%, 19.2% vs tiaprost: 36.7%, 50.0%, 13.3%], and conception rates [luprostiol: 12/25 (48.0%) vs tiaprost: 14/28 (50.0%); P>0.05]. In Experiment 2, oestrous detection efficiency, interval to oestrus and conception rate were similar between treatments [97/149 (65.1%), 71.1 h, 43/95 (45.3%) for PGF2α vs 130/188 (69.1%), 68.2h, 65/126 (51.6%) for GnRH-PGF2α, respectively]. However the oestrous distribution was more concentrated in GnRH-PGF2α treated animals (P<0.01).

Ram effect: Adult rams induce a greater reproductive response in anestrous ewes than yearling rams

2008 ◽  
Vol 103 (3-4) ◽  
pp. 271-277 ◽  
Author(s):  
R. Ungerfeld ◽  
M.A. Ramos ◽  
S.P. González-Pensado
Keyword(s):  
Reproductive Response ◽  
Ram Effect

Endocrine response patterns and psychological correlates

1982 ◽  
Vol 26 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Ragnar Vaernes ◽  
Holger Ursin ◽  
Austin Darragh ◽  
Ronan Lambe
Keyword(s):  
Response Patterns ◽  
Endocrine Response ◽  
Psychological Correlates

Ovarian response patterns to human menopausal gonadotropin in mixed hyperandrogenemia

1990 ◽  
Vol 123 (6) ◽  
pp. 598-602
Author(s):  
Miklos Hamori ◽  
Attila Török ◽  
Manfred Zwirner ◽  
Hans-Rudolf Tinneberg
Keyword(s):  
Follicular Development ◽  
Ovarian Response ◽  
Human Menopausal Gonadotropin ◽  
Response Patterns ◽  
Polycystic Ovaries ◽  
Ovarian Volume ◽  
Wide Range ◽  
Suppression Test ◽  
Dexamethasone Suppression ◽  
Stimulation Of

Abstract. Twenty-eight hyperandrogenemic women suffering from infertility owing to chronic anovulation were treated with hMG. Only 7 patients exhibited the typical polycystic ovarian appearance of multiple subcortical cysts, however, a wide range (6-15 cm3) of ovarian volume was observed. The LH/FSH ratio was consistently lower than 2.5 and circulating androgens of both ovarian and adrenal origin were elevated. The 4 days dexamethasone suppression test showed more than 80% suppression of dehydroepiandrosterone-sulphate and a variable (40-60%) reduction of testosterone and androstenedione levels. Two different patterns of follicular development were observed in response to hMG. Sixteen patients exhibited polycystic ovarian reaction, whereas 12 women had a follicular growth pattern similar to that seen in hMG-stimulated normo-ovulatory subjects. Patients with polycystic ovarian reaction showed a significantly increased androstenedione response to hMG when compared with the other group. Moreover, the non-stimulated ovarian volume was found to be markedly greater than in subjects without polycystic reaction. Thus, ovarian stimulation of patients with mixed hyperandrogenemia may elucidate the presence of borderline polycystic ovaries; furthermore the increased accumulation of androstenedione may suggest an inherent ovarian failure.

Endocrine Response Patterns to Acute Unilateral and Bilateral Resistance Exercise in Men

2010 ◽  
Vol 24 (1) ◽  
pp. 128-134 ◽  
Author(s):  
Matthew J Migiano ◽  
Jakob L Vingren ◽  
Jeff S Volek ◽  
Carl M Maresh ◽  
Maren S Fragala ◽  
...  
Keyword(s):  
Resistance Exercise ◽  
Response Patterns ◽  
Endocrine Response

Declining fertility in dairy cattle: changes in traditional and endocrine parameters of fertility

2000 ◽  
Vol 70 (3) ◽  
pp. 487-501 ◽  
Author(s):  
M. D. Royal ◽  
A. O. Darwash ◽  
A. P. F. Flint ◽  
R. Webb ◽  
J. A. Woolliams ◽  
...  
Keyword(s):  
Reproductive Performance ◽  
Average Rate ◽  
Post Partum ◽  
Current Status ◽  
Dairy Herds ◽  
Type I ◽  
Type Ii ◽  
Holstein Friesian ◽  
Endocrine Parameters ◽  
Comparison Of The Results

AbstractReproductive performance of 714 Holstein Friesian dairy cows was monitored between October 1995 and June 1998 using thrice weekly milk progesterone determinations. Defined endocrine parameters such as interval topost-partumcommencement of luteal activity, inter-ovulatory interval and length of luteal and inter-luteal intervals were used with a number of traditional measures of reproductive performance to investigate the current status of fertility in a sample of United Kingdom dairy herds. A comparison of the results of the 1995 to 1998 trial with those of a previous (1975 to 1982) milk progesterone database, which included 2503 lactations in British Friesian cows monitored using a similar milk sampling protocol, revealed a decline infertility between these periods.Between 1975-1982 and 1995-1998, pregnancy rate to first service declined from 55·6% to 39·7% (P< 0·001), at a derived average rate approaching 1% per year. This decline was associated with an increase (P< 0·001) in the proportion of animals with one or more atypical ovarian hormone patterns from 32% to 44%. There was a significant (P< 0·001) increase in the incidence of delayed luteolysis during the first cyclepost partum(delayed luteolysis type I; 7·3% to 18·2%) and during subsequent cycles (delayed luteolysis type II; 6·4% to 16·8%), although the incidence of prolonged anovulation post partům (delayed ovulation type I; 10·9% to 12·9%) and prolonged inter-luteal intervals (delayed ovulation type II; 12·9% to 10·6%) did not alter significantly. These changes resulted in an increase in mean luteal phase length from 12·9 (s.e. 0·09) to 14·8 (s.e. 0·17) days and an increase in inter-ovulatory interval from 20·2 (s.e. 0·1) to 22·3 (s.e. 0·2) days. The decline infertility was also reflected in traditional measures of fertility since although interval to first service remained relatively unchanged (74·0 (s.e. 0·4) to 77·6 (s.e. 1·1) days) calving interval lengthened from 370 (s.e. 2·2) to 390 (s.e. 2·5) days. Collectively these changes may have contributed to the decline in pregnancy rates observed over the last 20 years.

scholarly journals The reproductive response of rams to thyroidectomy: mediation by impaired inhibin feedback rather than a change in LH pulsatility

Reproduction ◽  
2003 ◽  
pp. 353-364 ◽  
Author(s):  
GM Anderson ◽  
KR Lapwood ◽  
PG Knight ◽  
TJ Parkinson
Keyword(s):  
Follicular Fluid ◽  
Suppressive Effect ◽  
Late Winter ◽  
Lh Pulsatility ◽  
Reproductive Response ◽  
Thyroid Glands ◽  
Series Of Experiments ◽  
Hypothalamic Mechanism ◽  
Stimulation Of

A series of experiments was conducted to examine the mechanism by which removal of the thyroid glands in seasonally suppressed rams brings about rapid testicular growth. In the first experiment, thyroidectomy at the nadir of the testicular cycle (late winter) initiated testis growth without any detectable change in the extent of spermatogenesis compared with sham-operated controls. The serum concentration of FSH, but not LH, was also markedly increased by thyroidectomy. In the second experiment, serum FSH concentration was again increased by thyroidectomy in late winter but there was no effect of thyroidectomy on LH concentration, LH pulses (measured in frequent blood samples) or testosterone concentration. Furthermore, there was no evidence of a change in central dopaminergic inhibition of GnRH, as measured by the pulsatile LH response to an i.m. injection of the dopaminergic D(2) agonist bromocriptine or antagonist sulpiride. The rapid increase in FSH concentration occurred despite a markedly increased serum inhibin A concentration in thyroidectomized rams. Therefore, the efficacy of inhibin feedback was examined by testing the FSH-suppressive effect of an inhibin preparation (5 ml charcoal-stripped bovine follicular fluid i.v.) in long-term thyroidectomized and thyroid intact castrated rams. Bovine follicular fluid suppressed FSH concentrations in control rams as expected but in marked contrast, was completely without effect in thyroidectomized animals. In castrated rams, the FSH concentration was only marginally increased by thyroidectomy, indicating that there is a major component of the mediation of the effects of thyroidectomy that is testicular in origin. It was concluded that a reduction in the ability of endogenous inhibin to inhibit FSH release at the pituitary, rather than a hypothalamic mechanism, is the primary cause of the stimulation of testis growth by thyroidectomy.

The effect of melatonin treatment on the ovarian response of ewes to the ram effect

2006 ◽  
Vol 31 (1) ◽  
pp. 52-62 ◽  
Author(s):  
J.A. Abecia ◽  
I. Palacín ◽  
F. Forcada ◽  
J.A. Valares
Keyword(s):  
Ovarian Response ◽  
Melatonin Treatment ◽  
Ram Effect
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