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Abstract
Estrus synchronization and manipulation are a tool that has been used by producers to provide uniform lamb and kid meat production and dairy sheep and goat milk production, to concentrate work and labor cost, and to plan for the lambing and kidding time. Breeders can also use estrus synchronization to stimulate ewes and does to exhibit estrus and ovulate outside of the breeding season, although both the ovulation rate and pregnancy rate may be decreased. To increase the ovulation rate outside of the breeding season, a variety of estrus synchronization methods have been used.
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Affiliation(s)
| | - Michelle Anne Kutzler
- Animal and Rangeland Science, Oregon State University, 112 Withycombe Hall, Corvallis, OR 97331, USA
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Hawken PAR, Smith JT, Jorre de St Jorre T, Esmaili T, Scott CJ, Rodger J, Blache D, Martin GB. Patterns of preoptic-hypothalamic neuronal activation and LH secretion in female sheep following the introduction and withdrawal of novel males. Reprod Fertil Dev 2019; 31:1674-1681. [PMID: 31511142 DOI: 10.1071/rd19079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/14/2019] [Indexed: 11/23/2022] Open
Abstract
The neuroendocrine response of female sheep to a novel male involves neural activation in the hypothalamus. However, if males are removed, the gonadotrophic signal declines, so the neural activity is likely to change. We examined Fos-immunoreactive (IR) cells in hypothalamic tissues from seasonally anovulatory female sheep exposed to males for 2 or 6h, or for 2h followed by 4h isolation from males. Control females were killed in the absence of male exposure. Male introduction increased LH secretion in all females; male removal was associated with a reduction only in mean and basal LH concentrations. Females exposed to males for 2h had more Fos-IR cells in the arcuate nucleus (ARC), ventromedial nucleus of the hypothalamus (VMH) and organum vasculosum of the lamina terminalis (OVLT) than control females. Fos-IR cells in the preoptic area (POA) were only greater than in control females after 6h exposure to a male. Removal of males decreased the number of Fos-IR cells in the ARC, VMH and OVLT, but not in the POA. Thus, hypothalamic neural activation and LH secretion in female sheep are stimulated by males and decline after male removal. However, activation in the POA persists after removal and may explain the incomplete decline in the LH response.
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Affiliation(s)
- Penny A R Hawken
- School of Agriculture and Environment, The University of Western Australia, Crawley, WA 6009, Australia
| | - Jeremy T Smith
- School of Human Sciences, The University of Western Australia, Crawley, WA 6009, Australia
| | - Trina Jorre de St Jorre
- School of Agriculture and Environment, The University of Western Australia, Crawley, WA 6009, Australia
| | - Tammi Esmaili
- La Trobe University, Cnr Plenty Road and Kingsbury Drive, Melbourne, Vic. 3086, Australia
| | - Christopher J Scott
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
| | - Jennifer Rodger
- School of Biological Sciences, The University of Western Australia, Crawley, WA 6009, Australia; and Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia
| | - Dominique Blache
- School of Agriculture and Environment, The University of Western Australia, Crawley, WA 6009, Australia
| | - Graeme B Martin
- School of Agriculture and Environment, The University of Western Australia, Crawley, WA 6009, Australia; and Corresponding author.
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Christian CA, Moenter SM. The neurobiology of preovulatory and estradiol-induced gonadotropin-releasing hormone surges. Endocr Rev 2010; 31:544-77. [PMID: 20237240 PMCID: PMC3365847 DOI: 10.1210/er.2009-0023] [Citation(s) in RCA: 207] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 02/18/2010] [Indexed: 12/14/2022]
Abstract
Ovarian steroids normally exert homeostatic negative feedback on GnRH release. During sustained exposure to elevated estradiol in the late follicular phase of the reproductive cycle, however, the feedback action of estradiol switches to positive, inducing a surge of GnRH release from the brain, which signals the pituitary LH surge that triggers ovulation. In rodents, this switch appears dependent on a circadian signal that times the surge to a specific time of day (e.g., late afternoon in nocturnal species). Although the precise nature of this daily signal and the mechanism of the switch from negative to positive feedback have remained elusive, work in the past decade has provided much insight into the role of circadian/diurnal and estradiol-dependent signals in GnRH/LH surge regulation and timing. Here we review the current knowledge of the neurobiology of the GnRH surge, in particular the actions of estradiol on GnRH neurons and their synaptic afferents, the regulation of GnRH neurons by fast synaptic transmission mediated by the neurotransmitters gamma-aminobutyric acid and glutamate, and the host of excitatory and inhibitory neuromodulators including kisspeptin, vasoactive intestinal polypeptide, catecholamines, neurokinin B, and RFamide-related peptides, that appear essential for GnRH surge regulation, and ultimately ovulation and fertility.
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Affiliation(s)
- Catherine A Christian
- Departments of Medicine and Cell Biology, University of Virginia, Charlottesville, 22908, USA.
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Delgadillo JA, Gelez H, Ungerfeld R, Hawken PAR, Martin GB. The 'male effect' in sheep and goats--revisiting the dogmas. Behav Brain Res 2009; 200:304-14. [PMID: 19374015 DOI: 10.1016/j.bbr.2009.02.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Male-induced ovulation in sheep and goats (the 'male effect'), documented during the period 1940-1960, has long been shrouded in preconceptions concerning how, when and why it worked. These preconceptions became dogmas but recent research is challenging them so, in this review, we have re-visited some major physiological (breed seasonality; characteristics of the response; the nature of the male stimuli) and physical factors (duration of male presence; isolation from male stimuli) that affect the phenomenon. We reject the dogma that ewes must be isolated from males and conclude that male 'novelty' is more important than isolation per se. Similarly, we reject the perception that the neuroendocrine component of the male effect is restricted to anovulatory females. Finally, we re-assess the relative importance of olfactory and non-olfactory signals, and develop a perspective on the way male-induced ovulation fits with preconceptions about pheromonal processes in mammals. Overall, our understanding of the male effect has evolved significantly and it is time to modify or reject our dogmas so this field of research can advance. We can now ask new questions regarding the application of the male effect in industry and develop research so we can fully understand this biological phenomenon.
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Affiliation(s)
- J Alberto Delgadillo
- Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, Coahuila, Mexico.
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Ungerfeld R, Carbajal B, Rubianes E, Forsberg M. Endocrine and ovarian changes in response to the ram effect in medroxyprogesterone acetate-primed Corriedale ewes during the breeding and nonbreeding season. Acta Vet Scand 2005; 46:33-44. [PMID: 16108211 PMCID: PMC2202782 DOI: 10.1186/1751-0147-46-33] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Two experiments were performed to determine the endocrine and ovarian changes in medroxyprogesterone acetate (MAP)-primed ewes after ram introduction. Experiment 1 was performed during the mid-breeding season with 71 ewes primed with an intravaginal MAP sponge for 12 days. While the control (C) ewes (n = 35) were in permanent contact with rams, the ram effect (RE) ewes (n = 36) were isolated for 34 days prior to contact with rams. At sponge withdrawal, all ewes were joined with eight sexually experienced marking Corriedale rams and estrus was recorded over the next 4 days. The ovaries were observed by laparoscopy 4-6 days after estrus. Four weeks later, pregnancy was determined by transrectal ultrasonography. In eight ewes from each group, ovaries were ultrasonographically scanned; FSH, LH, and estradiol-17beta were measured every 12 hours until ovulation or 96 hours after estrus. The response to the rams was not affected by the fact that ewes had been kept or not in close contact with males before teasing. No differences were found in FSH, LH, estradiol-17beta concentrations, growth of the ovulatory follicle, onset of estrus, ovulation rate, or pregnancy rate. Experiment 2 was performed with 14 ewes during the nonbreeding season. Ewes were isolated from rams for 1 month, and received a 6-day MAP priming. Ovaries were ultrasonographically scanned every 12 hours, and FSH, LH, estradiol-17beta, and progesterone were measured. Ewes that ovulated and came into estrus had higher FSH and estradiol-17beta levels before introduction of the rams than did ewes that had a silent ovulation. The endocrine pattern of the induced follicular phase of ewes that came into estrus was more similar to a normal follicular phase, than in ewes that had a silent ovulation. The follicle that finally ovulated tended to emerge earlier and in a more synchronized fashion in those ewes that did come into estrus. All ewes that ovulated had an LH surge and reached higher maximum FSH levels than ewes that did not ovulate, none of which had an LH surge. We conclude that (a) the effect of ram introduction in cyclic ewes treated with MAP may vary depending on the time of the breeding season at which teasing is performed; (b) patterns of FSH, and estradiol-17beta concentrations, as indicators of activity of the reproductive axis, may be used to classify depth of anestrus; and (c) the endocrine pattern of the induced follicular phase, which is related to the depth of anestrus, may be reflected in the behavioral responses to MAP priming and the ram effect.
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Affiliation(s)
- R Ungerfeld
- Departamento de Fisiología, Facultad de Veterinaria, Lasplaces 1550, Montevideo 11600, Uruguay.
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Martínez G, Urrutia J, Martínez L, Meza-Herrera CA. Reproductive Performance of Merino Rambouillet Prepubertal Ewes Under Highland Sub-Tropical Conditions II. Male Stimulation of Seasonal Anestrous. JOURNAL OF APPLIED ANIMAL RESEARCH 2005. [DOI: 10.1080/09712119.2005.9706531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Ungerfeld R, Forsberg M, Rubianes E. Overview of the response of anoestrous ewes to the ram effect. Reprod Fertil Dev 2004. [DOI: 10.1071/rd04039] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
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.
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Blache D, Fabre-Nys C, Venier G. Inhibition of sexual behaviour and the luteinizing hormone surge by intracerebral progesterone implants in the female sheep. Brain Res 1996; 741:117-22. [PMID: 9001713 DOI: 10.1016/s0006-8993(96)00907-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In female sheep, progesterone blocks the induction by oestradiol of both sexual behaviour and the pre-ovulatory surges of gonadotrophin releasing hormone (GnRH) and luteinising hormone (LH). However, the central sites of action of progesterone remain poorly defined, so we attempted to locate them by implanting progesterone intracerebrally in ovariectomised ewes treated with exogenous steroids to induce oestrous behaviour and the LH surge. Single bilateral implants or a double bilateral implants filled with progesterone or cholesterol were placed in the ventromedial hypothalamus (VMH) or the preoptic area (POA). Control ewes were not implanted. To determine the inhibitory capacity of the central progesterone implants, ewes received an injection (i.m.) of 8 micrograms or 16 micrograms of oestradiol. The single bilateral implants of progesterone failed to block oestrous behaviour and the LH surge induced by 8 micrograms of oestradiol. Double bilateral progesterone implants in the VMH blocked the sexual behaviour (P < 0.05) and the LH surge (P < 0.05), but implants in the POA blocked only sexual receptivity (P < 0.05). No changes were observed after central implantation of cholesterol. Our results support the hypothesis that progesterone acts centrally in the VMH and the POA to inhibit the induction of LH surge and sexual behaviour by oestradiol.
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Affiliation(s)
- D Blache
- Centre de Recherche INRA/URA 1921, Laboratoire de Comportement Animal, Nouzilly, France.
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Blache D, Batailler M, Fabre-Nys C. Oestrogen receptors in the preoptico-hypothalamic continuum: immunohistochemical study of the distribution and cell density during induced oestrous cycle in ovariectomized ewe. J Neuroendocrinol 1994; 6:329-39. [PMID: 7920599 DOI: 10.1111/j.1365-2826.1994.tb00590.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Oestrogen plays a key role in the regulation of the endocrine and behavioural events associated with the oestrous cycle. It is important, therefore, to know the location of neurones receptive to this steroid and to know whether their distribution varies with the oestrous cycle. We have undertaken experiments to identify the location of oestrogen receptors (ER) within the preoptico-hypothalamic continuum of ovariectomized ewes submitted to a variety of different hormone replacement regimes which mimic the different stages of the oestrous cycle. We used a monoclonal antibody to ER and detected receptors with immunohistological methods in the non-vascular part of the organum vasculosum of the lamina terminalis, the lateral septum, the medial preoptic area, the supraoptic, suprachiasmatic and arcuate (ARC) nuclei, the ventromedial hypothalamus (HVM) and in the region close to the mamillari recess. ER neurones were scarce or absent from the anterior hypothalamus and the paraventricular nucleus. The density of ER staining in the HVM, but in no other localization, was found to be higher, and in a more lateral position, during the induced luteal phase (progesterone treatment) than during the follicular phase (7 days of progesterone treatment followed by oestradiol) or in the ovariectomized female. In all areas studied, except for the ARC, the apparent surface area of the nucleus in ER immunoreactive cells varied with hormonal treatment. These data, and especially those in the HVM, contribute towards our understanding of how steroids may act in the ovine to control sexual behaviour.
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Affiliation(s)
- D Blache
- Centre de Recherches INRA/CNRS URA 1291, Laboratoire de Comportement Animal, Nouzilly, France
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Ovarian stimulation following repeated injections of LH or LH + FSH in Ile-de-France sheep in early and mid-seasonal anoestrus. Anim Reprod Sci 1993. [DOI: 10.1016/0378-4320(93)90029-q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Effect of season on plasma concentrations of prolactin and cortisol in pregnant, non-pregnant and lactating ewes. Anim Reprod Sci 1991. [DOI: 10.1016/0378-4320(91)90051-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Thiery JC. Monoamine content of the stalk-median eminence and hypothalamus in adult female sheep as affected by daylength. J Neuroendocrinol 1991; 3:407-11. [PMID: 19215484 DOI: 10.1111/j.1365-2826.1991.tb00295.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Abstract In the ewe, plasma luteinizing hormone and prolactin concentrations exhibit seasonal variations. During long days, inhibition of pulsatile luteinizing hormone secretion is mediated by monoamines. In a model of ovariectomized ewes bearing a subcutaneous oestradiol implant, we previously showed that the steroid-dependent inhibition of luteinizing hormone involves the A15 dopaminergic nucleus of the retrochiasmatic area. In the present work, we compared the aminergic activities of tele-diencephalic structures in groups of ovariectomized ewes under artificial illumination for short versus long days (8 versus 16 h/day of light, respectively). Half the animals in each group were bearing a subcutaneous oestradiol implant. Using high-performance liquid chromatography and electrochemical detection, we measured the levels of amines and amine metabolites in 'punches' of tissues from regions containing luteinizing hormone-releasing hormone axon terminals or cell bodies and catecholaminergic structures. Concurrently, we checked the pulsatile luteinizing hormone release and plasma prolactin concentration to assess the ability of our model to mimic seasonal changes in the hormonal status. As expected, ovariectomized ewes with a subcutaneous oestradiol implant showed an inhibition of the pulsatile luteinizing hormone release under long days. A higher concentration of plasma prolactin was also observed under long days, without any effect of the steroid treatment. Under this light regimen, statistically significant higher contents of dopamine than under short days were found in the stalk-median eminence. Larger contents of homovanillic acid, a dopamine metabolite, and 4-hydroxy-3-methoxyphenylethyleneglycol (MHPG), a noradrenaline metabolite were observed in the infundibular nucleus, while the catechola-mines themselves remained unchanged. Furthermore, oestradiol also significantly increased the content of MHPG in the latter structure. During long days, animals without oestradiol treatment exhibited a significant lower content of noradrenaline in the A15 nucleus, without any alteration of the dopamine content. Daylength or oestradiol treatment had no significant effects on the levels of amines or amine metabolites in the preoptic or septal areas. Thus, our results in the ewe underline the role played by the medial basal hypothalamus in the catecholaminergic regulation of seasonal changes in hormone release and suggest modifications in the turnover of the neurotransmitters in some structures.
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Affiliation(s)
- J C Thiery
- INRA, Reproductive Physiology Station, 37380 Nouzilly, France
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Blache D, Fabre-Nys CJ, Venier G. Ventromedial hypothalamus as a target for oestradiol action on proceptivity, receptivity and luteinizing hormone surge of the ewe. Brain Res 1991; 546:241-9. [PMID: 2070261 DOI: 10.1016/0006-8993(91)91488-m] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Most of the literature suggests that in sheep as in rodents nervous structures involved in female sexual behaviour are not necessarily identical to those involved in the LH surge. In rodents, oestradiol triggers female sexual behaviour by acting on a restricted area of the mediobasal hypothalamus whereas the concomitant induction of the preovulatory LH surge is at least partially under the control of more anterior structures. The central sites of oestradiol action, however, remained poorly defined in sheep. To provide this definition, 37 ovariectomized ewes were stereotaxically implanted unilaterally or bilaterally with a guide cannula in preoptic area (POA), anterior, mediobasal, lateral, or posterior hypothalamus (AH, MBH, LHT, PH). Experiments were made during the breeding season (Br) and the anoestrous period (An: unilat only) and females were primed with a peripheral treatment of progesterone and a dose of 17 beta-oestradiol subthreshold for both the LH surge and sexual behaviour. Intracranial implants (i.d. = 0.45 mm) of crystalline E2 were lowered 16 h after progesterone removal and left in the brain for 48 h. Whereas POA implants never had any significant effects on either the behaviour or the LH surge, all MBH implants caused receptivity (11 bilat, 5 unilat Br and 5 unilat An). Bilateral MBH implants also induced proceptivity in 9 of 11 ewes and increased the LH levels in 7 of them. These proportions do not differ significantly from those observed after a 25 microgram peripheral injection of E2. Unilateral MBH implants had no significant effect on proceptivity and LH increase but oestrous behaviour was induced by some implants placed laterally to the MBH (25 recept and 3/5 procept).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D Blache
- Centre de recherche INRA/CNRS Tours, Unité de physiologie de la reproduction des mammifères domestiques, Monnaie, France
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King R, Martin G. Relationships between protein intake during lactation, LH levels and oestrous activity in first-litter sows. Anim Reprod Sci 1989. [DOI: 10.1016/0378-4320(89)90101-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Artificial breeding of adult goats and kids induced with hormones to ovulate outside the breeding season. Small Rumin Res 1988. [DOI: 10.1016/0921-4488(88)90041-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Martin GB, Sutherland SR, Lindsay DR. Effects of nutritional supplements on testicular size and the secretion of LH and testosterone in Merino and Booroola rams. Anim Reprod Sci 1987. [DOI: 10.1016/0378-4320(87)90098-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Martin GB, Oldham CM, Cognié Y, Pearce DT. The physiological responses of anovulatory ewes to the introduction of rams — A review. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/0301-6226(86)90031-x] [Citation(s) in RCA: 205] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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