Seasonal variation in oestrus and ovarian activity of Finnish Landrace, Tasmanian Merino and Scottish Blackface ewes

1977 ◽  
Vol 24 (3) ◽  
pp. 363-376 ◽  
Author(s):  
A. G. Wheeler ◽  
R. B. Land
Keyword(s):  
Seasonal Variation ◽  
Breeding Season ◽  
Venous Blood ◽  
Plasma Free Fatty Acid ◽  
Reproductive Activity ◽  
Ovulation Rate ◽  
Ovarian Activity ◽  
Progesterone Concentration ◽  
Luteal Function ◽  
Breeding Seasons

SUMMARYThe patterns of seasonal variation in reproductive activity were observed over a period of 15 mo for approximately 15 females of each of three breeds: Finnish Landrace (Finn), Tasmanian Merino (Merino) and Scottish Blackface (Blackface). The incidence of oestrus was measured by teasing with vasectomized rams, and the incidence and rate of ovulation were determined frequently by laparoscopy. Luteal function was assessed from peripheral venous blood progesterone concentration on days 7 and 11 of the oestrous cycle. Nutritional status was monitored by recording body weight and plasma-free fatty acid levels throughout the study.The breeding seasons differed significantly: Finn, October to May; Merino, September to February; and Blackface, October to February. Variation in the incidence of ovulation was similar to that in the incidence of oestrus for each breed. The incidence of silent ovulation varied with the breed, being greatest in the Merino and least in the Finn. The ovulation rate varied among breeds (Finn, 2·99; Merino, 1·08 and Blackface, 1·30), and during the breeding season (e.g. Finn: November, 3·5; March, 2·6). Follicles were observed in each breed throughout the period of study.The pattern of variation in progesterone concentration was similar for each breed despite their different breeding seasons. In addition to breed differences in ovulation rate and in onset and end of the breeding season, the sensitivity to oestrogen was apparently such that, with the Finn if oestrogen secretion was high enough to stimulate ovulation it would usually also stimulate oestrus, whereas with the Merino ovulation often occurred without oestrus; this suggests that in the Merino the centres controlling ovulation are more sensitive to oestrogen than those controlling behaviour.

scholarly journals Effect of a GnRH agonist (deslorelin) on ovarian activity in leopard geckos (Eublepharis macularius)

2019 ◽  
Vol 64 (No. 5) ◽  
pp. 228-230
Author(s):  
E Cermakova ◽  
M Oliveri ◽  
Z Knotkova ◽  
Z Knotek
Keyword(s):  
Gnrh Agonist ◽  
Weight Control ◽  
Healthy Adult ◽  
Reproductive Function ◽  
Reproductive Activity ◽  
Ovarian Activity ◽  
Eublepharis Macularius ◽  
Nesting Sites ◽  
Healthy Adult Male ◽  
Breeding Seasons

The aim of this study was to evaluate the effectiveness of deslorelin acetate in the regulation of reproductive activity in captive leopard geckos (Eublepharis macularius). Fourteen healthy adult females were separated into two groups. Under general anaesthesia, deslorelin acetate implants (4.7 mg) or placebo implants were administered into the coelom of ten female geckos and four female geckos, respectively. One healthy adult male Leopard gecko was added to each group of females (five females with GnRH implants and two females with placebo implants). The geckos were regularly monitored over two breeding seasons (visual examination, weight control). Nesting sites were checked daily. There were no postoperative complications or any other health problems during the study. Implant administration did not result in long-term suppression of reproductive function. No significant differences were found in the number of clutches between the female groups (deslorelin implants versus placebo implants) or in the number of clutches between the two breeding seasons. Deslorelin acetate implants did not interfere with ovarian activity in captive female leopard geckos. The use of GnRH agonist implants is not an appropriate method for control of reproductive function in female leopard geckos.

Influence of lambing date on subsequent ovarian cyclicity and ovulation rate in ewes

1997 ◽  
Vol 65 (1) ◽  
pp. 75-81 ◽  
Author(s):  
L. M. Mitchell ◽  
M. E. King ◽  
R. P. Aitken ◽  
J. M. Wallace
Keyword(s):  
Breeding Season ◽  
Ovulation Rate ◽  
Breeding Period ◽  
Ovarian Activity ◽  
Blood Samples ◽  
Natural Breeding ◽  
Seasonal Decline ◽  
Ovarian Cyclicity ◽  
Ovarian Cycles ◽  
Subsequent Onset

AbstractThe effect of lambing date on the subsequent onset and duration of ovarian cyclicity in Mule (Bluefaced Leicester × Scottish Blackface) ewes was investigated. Nineteen ewes which had lambed in January (16 January 1993 (s.e. 3 days)) and been weaned in February-March and 22 comparable ewes which had lambed in May (14 May 1993 (s.e. 2 days)) and been weaned on 23 August were maintained at pasture as two isolated groups. A raddled vasectomized ram was continually present with each group from 14 July 1993 to 26 May 1994 and marked (oestrous) ewes were recorded twice weekly. Ovarian activity was assessed by measuring peripheral progesterone concentrations in blood samples collected twice weekly and by laparoscopic viewing of the ovaries of all ewes during October, January and March. The onset and duration of ovarian activity were significantly affected by the previous lambing date. For January and May lambing ewes, mean dates of onset were 5 September 1993 (s.e. 2 days) v. 25 September 1993 (s.e. 4 days) (P < 0·001) and of cessation were 5 April 1994 (s.e. 5 days) v. 10 April 1994 (s.e. 3 days). Mean durations of ovarian activity were 212 (s.e. 6) and 195 (s.e. 5) days (P < 0·05) during which 12·4 (s.e. 0·29) and 11·5 (s.e. 0·38) ovarian cycles respectively were recorded. Ovulation rate was not affected by previous lambing date but was significantly lower in March compared with October (January lambing ewes 1·7 (s.e. 0·1) v. 2·3 (s.e. 0·1) (P < 0·001); May lambing ewes 1·6 (s.e. 0·1) v. 2·1 (s.e. 0·1) (P < 0·01)). Results demonstrate that (i) Mule ewes have a potential breeding season of up to 8 months duration; (ii) the onset and duration of ovarian activity can be influenced by previous lambing date; and (Hi) a seasonal decline in ovulation rate may, in practical terms, result in a lower lambing percentage for animals bred towards the end of their natural breeding period.

Effects of immunization against recombinant bovine inhibin α subunit on circulating concentrations of gonadotrophins in ewes

1989 ◽  
Vol 120 (1) ◽  
pp. 59-65 ◽  
Author(s):  
J. K. Findlay ◽  
B. Doughton ◽  
D. M. Robertson ◽  
R. G. Forage
Keyword(s):  
Breeding Season ◽  
Untreated Control ◽  
Luteal Phase ◽  
Plasma Concentrations ◽  
Follicular Phase ◽  
Ovulation Rate ◽  
Α Subunit ◽  
Keyhole Limpet Haemocyanin ◽  
Fourfold Increase ◽  
Breeding Seasons

ABSTRACT Immunization of ewes against a pure recombinant preparation of the α subunit of bovine inhibin (α-bI) resulted in a three- to fourfold increase in ovulation rate, associated with antibodies in plasma recognizing pure native 31 kDa inhibin. The aim of this study was to examine the effects of this immunization on basal and GnRH-stimulated plasma concentrations of FSH and LH in ewes during the anoestrous and breeding seasons. The groups were untreated control ewes (n = 5), control ewes treated with keyhole limpet haemocyanin (KLH alone, n = 4), ewes treated with α-bI alone (n = 4) and α-bI–KLH conjugate-treated ewes (n = 3). There were no effects of immunization on basal FSH or LH in anoestrous ewes, despite the presence of antibodies recognizing 31 kDa inhibin. In the breeding season, immunization against α-bI resulted in increased basal (follicular phase, P < 0·1; luteal phase P < 0·05) and GnRH-stimulated (follicular phase only, P < 0·001) release of FSH, but not LH. The data are compatible with the hypotheses that the increase in ovulation rate in immunized ewes is due to an increase in circulating FSH concentrations and that inhibin may only have a major peripheral influence on FSH in sheep during the breeding season. Journal of Endocrinology (1989) 120, 59–65

scholarly journals Direct in vivo effects of leptin on ovarian steroidogenesis in sheep

Reproduction ◽  
2004 ◽  
Vol 128 (6) ◽  
pp. 757-765 ◽  
Author(s):  
N R Kendall ◽  
C G Gutierrez ◽  
R J Scaramuzzi ◽  
D T Baird ◽  
R Webb ◽  
...  
Keyword(s):  
Ovarian Function ◽  
Venous Blood ◽  
Regulatory System ◽  
Reproductive Activity ◽  
High Dose ◽  
Passive Immunisation ◽  
Direct Role ◽  
Ovarian Steroidogenesis ◽  
Luteal Function

Leptin, the metabolic fat hormone, has been shown to have effects on reproduction in mice and to modulate steroid production by cultured ovarian somatic cells in a number of species. However, a direct role of leptin on normal ovarian function in vivo has not been shown. In this paper the effect of passive immunisation against leptin (experiment 1; 20 ml antiserum or non-immune plasma i.v.; n = 6/treatment) and direct ovarian infusion of leptin (experiment 2; 0, 2 or 20 μg recombinant ovine leptin; n = 4/treatment) during the early follicular phase was investigated in sheep with ovarian autotransplants, which allow recovery of ovarian venous blood and regular non-invasive scanning of the ovary. Passive immunisation against leptin resulted in an acute increase (P < 0.05) in ovarian oestradiol secretion but had no effect on gonadotrophin concentrations, ovulation or subsequent luteal function. Conversely, direct ovarian arterial infusion of the low dose of leptin resulted in an acute decline (P < 0.05) in ovarian oestradiol secretion whereas the high dose, which resulted in supra-physiological leptin concentrations, had no effect on oestradiol production compared with the controls. Neither dose of leptin had any effect on gonadotrophin concentrations or ovulation but both doses resulted in an increase (P < 0.05) in progesterone concentrations over the subsequent luteal phase. In conclusion, together these data provide strong in vivo evidence that leptin can modulate ovarian steroidogenesis directly and acutely in ruminants and suggest that leptin is an alternate regulatory system whereby nutritional status can regulate reproductive activity.

Studies on Progesterone Concentration and Fertility Response in Postpartum Subestrus Buffaloes during Breeding and Low Breeding Seasons

2021 ◽  
Author(s):  
B. Chandra Prasad ◽  
G. Venkata Naidu ◽  
M. Srinivas ◽  
M. Raghunath ◽  
Ashwini Kumar
Keyword(s):  
Breeding Season ◽  
Bubalus Bubalis ◽  
Pregnancy Rates ◽  
Progesterone Concentration ◽  
Murrah Buffaloes ◽  
Farming Community ◽  
Livestock Sector ◽  
Gross Income ◽  
Breeding Seasons ◽  
Reproductive Problem

Background: The dairy and livestock sector plays a very important role in national economy of India by contributing close to one third of gross income of rural households and nearly half of gross income in case of those without land. Subestrus is the most prevalent, frustrating and challenging problem encountered in postpartum buffaloes. Postpartum subestrus is one of the most prevalent, frustrating and challenging reproductive problem encountered in rural resulting into prolonged inter-calving period, reduced milk production and thus greatly affecting the economy of our farming community. Methods: The present study was carried out on Graded Murrah buffaloes during the period from September 2017 to August 2019 (includes breeding and low breeding season) which were maintained at farm and field. Treatment of sub-estrus lactating graded Murrah buffaloes (Bubalus bubalis) using Double PGF2 α (DPG) and Presynch-Ovsynch (POVS) their influence on fertility in farm and field condition during breeding and low breeding season was studied. Total cholesterol and progesterone concentration was recorded during different days/period of protocols. Further, overall per cent conception and pregnancy rates were recorded and compared between two protocols. Result: Progesterone levels increased significantly on day 21 post AI in pregnant buffaloes, whereas decreased significantly in non-pregnant buffaloes both in farm and field during breeding and low breeding season. The overall per cent conception and pregnancy rates were higher in POVS group than DPG group at both farm and field as well as during breeding and low breeding seasons.

Seasonal variation in the ovarian activity of Merino ewes

1970 ◽  
Vol 10 (44) ◽  
pp. 267 ◽  
Author(s):  
IC Fletcher ◽  
PE Geytenbeek
Keyword(s):  
Seasonal Variation ◽  
Breeding Season ◽  
Early Summer ◽  
Constant Level ◽  
Ovarian Activity ◽  
Natural Breeding ◽  
Sudden Introduction

Ovulation was studied in a flock of medium Peppin Merino ewes known to show little seasonal variation in the incidence of twin births. In the absence of rams, ovarian activity was lowest in the spring and highest in the autumn, but the proportion of twin ovulations did not vary significantly from a constant level throughout the year. The incidence of twin ovulations, following an advanced onset of the breeding season, initiated by the sudden introduction of rams in the early summer, did not differ from that occurring during the 'natural' breeding season.

A note on the reproductive activity of Hampshire and Suffolk ewes outside the breeding season

1974 ◽  
Vol 19 (1) ◽  
pp. 123-126 ◽  
Author(s):  
L. L. Bellinger ◽  
V. E. Mendel
Keyword(s):  
Breeding Season ◽  
Reproductive Activity ◽  
Ovarian Activity ◽  
Natural Light ◽  
Cervical Smear ◽  
Light Reduction ◽  
Group I ◽  
Group Ii

SUMMARYThe present study investigated the intensity of the anoestrous period in 36 Hampshire and Suffolk ewes as influenced by the photoperiod and the presence of the ram. The study began on 4 April and terminated on 11 June. Ewes kept under natural light in the absence of the ram (Group I) exhibited a limited amount of ovarian activity as determined by cervical smear. Ewes kept under natural light, but in the presence of a ram (Group II) showed an increased amount of cycling (P < 0·05) when compared to that in Group I. Two ewes from Group II mated during the so-called anoestrous period and subse-quently lambed. Ten of 12 ewes, subjected to a decreased photoperiod (Group HI), increased ovarian activity within a few days of light reduction. Five ewes in this group lambed.

Seasonal Variation of the Intraepithelial Gland in Camel Epididymis with Special Reference to Autophagosome

2019 ◽  
Vol 25 (4) ◽  
pp. 1052-1060 ◽  
Author(s):  
Fatma M. Abdel-Maksoud ◽  
Manal T Hussein ◽  
Abdelraheim Attaai
Keyword(s):  
Seasonal Variation ◽  
Breeding Season ◽  
Reproductive Activity ◽  
Electron Microscopic ◽  
Transmission Electron Microscopic Study ◽  
Nonbreeding Season ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Ultrastructural Characteristics

AbstractThe key role of the epididymis is contributing to sperm storage, maturation, and survival. The epididymis of camel has a unique structure called the intraepithelial gland. The present work aimed to investigate the structure of the epididymal intraepithelial gland with special references to the seasonal variation. The samples were collected from the distal part of the corpus epididymes of completely healthy mature camels (Camelus dromedarius) in the breeding and nonbreeding seasons. Tomato lectin-positive material had been demonstrated within the epididymal spermatozoa. Here, we provide the first transmission electron microscopic study for the intraepithelial gland of camel epididymis detecting the autophagy during the nonbreeding season. The autophagosomes originated from the endoplasmic reticulum, surrounding mitochondria, and located mainly next to the basement membrane. This location is probably valuable for subsequent passing of their contents into the interstitium for possible recycling. The histochemical and ultrastructural characteristics of the gland in the breeding season indicated a hyperactive secretory microenvironment enriched with the glycoprotein-producing machinery, which could be controlled by androgens. The present data suggest that the camel intraepithelial gland has a significant impact on the reproductive activity through their secretory microenvironment during the breeding season. Moreover, it recycles the unused organelles or proteins for reuse or to supply energy under stress conditions in the nonbreeding season.

A QUANTITATIVE STUDY OF GENETIC DIFFERENCES IN THE INCIDENCE OF OESTRUS, OVULATION AND PLASMA LUTEINIZING HORMONE CONCENTRATION IN THE SHEEP

1973 ◽  
Vol 58 (2) ◽  
pp. 305-317 ◽  
Author(s):  
R. B. LAND ◽  
J. PELLETIER ◽  
J. THIMONIER ◽  
P. MAULÉON
Keyword(s):  
Seasonal Variation ◽  
Luteinizing Hormone ◽  
Breeding Season ◽  
Quantitative Study ◽  
Genetic Differences ◽  
Ovulation Rate ◽  
The Other ◽  
Corpora Lutea ◽  
Hormone Concentration ◽  
Luteinizing Hormone Concentration

SUMMARY Seasonal variation in the ovulation rate and incidence of ovulation was examined in 15 Romanov and 15 Solognote ewes by endoscopy. The ovulation rate of the Romanovs was found to be related to the incidence of ovulation (r = 0·78) and to the incidence of oestrus as measured by daily teasing with aproned entire rams (r = 0·83). The ovulation rate of the Romanovs was greater than that of the Solognotes, and was 2·6 and 1·1 corpora lutea in the two breeds, respectively, in the autumn. The durations of the breeding season and of oestrus of the Romanovs exceeded those of the Solognotes. The characteristics of the preovulatory discharge of luteinizing hormone (LH) and the daily plasma LH levels were studied by radioimmunoassay in the Romanov and Solognote ewes and in ewes of the Berrichon and Berrichon × Romanov breeds. The interval between the onset of oestrus and the discharge of LH was greater in the Romanovs (17·6 h) than in the other breeds (mean = 7·5 h). The total release of LH, however, was not related to the number of corpora lutea formed.

The effect of season on the ovulation rates of Merino and crossbreed ewes in Western Australia

1969 ◽  
Vol 9 (38) ◽  
pp. 267 ◽  
Author(s):  
HE Fels ◽  
HG Neil ◽  
IG Ralph ◽  
RJ Suiter
Keyword(s):  
Body Weight ◽  
Breeding Season ◽  
Body Condition ◽  
Ovulation Rate ◽  
The Other ◽  
Low Incidence ◽  
Breeding Seasons ◽  
Agricultural Areas ◽  
Western Australian ◽  
Teaser Rams

Five experiments involving Merino and Border Leicester X Merino crossbred ewes were carried out to investigate the effect of season on ovulation and ovulation rate in the Western Australian agricultural areas. In one experiment, involving Murray Merinos only, effects of body weight and of introduction of teaser rams were also investigated. In 1966 the breeding season began in January for Murray Merinos, but in 1966-67 some ewes had already ovulated in December. Introduction of teaser rams in early December made teased ewes ovulate sooner than unteased ewes. The number of ovulations per ewe ovulating increased during the breeding season, reaching peaks of 1.8 eggs per ewe ovulating in April and early May 1966, and 1.6 eggs per ewe ovulating in February 1967. Supplementary feeding hastened the onset of the breeding season and tended to increase ovulation rate. Peppin Merinos showed a low incidence of ovulation, which was ascribed to their very poor body condition. The Border Leicester X Merino crossbred ewes began their breeding season in March in one experiment, but more than half the ewes had already ovulated in December in the other experiment, perhaps because they were much heavier. Both group's showed marked increases in ovulation rate as their breeding seasons progressed.

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