Seasonal Changes in the Semen of Rams

Cupps, P. T.; McGowan, Brenda K.; Rahlmann, D. F.; Reddon, Adam R.; Weir, W. C.

doi:10.2527/jas1960.191208x

Cited by 29 publications

(24 citation statements)

References 3 publications

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“…In domestic sheep two annual peaks in the percentage of normal spermatozoa have been reported (Cupps, McGowan, Rahlmann, Reddon & Weir, 1980;Mickelsen et ai, 1981). Furthermore, endocrine and histological studies in red deer, white-tailed deer, black-tailed deer and roe deer (Capreolus capreolus) indicate that the seasonal rhythm does not have just one peak.…”

Section: Discussionmentioning

confidence: 93%

Relationships between seasonal changes in serum testosterone concentrations, scrotal circumference and sperm morphology of male wapiti (Cervus elaphus)

Haigh¹,

Cates²,

Glover³

et al. 1984

Reproduction

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One 2-year-old and 4 adult (greater than 3 years old) wapiti were studied throughout 1 year. Serum testosterone concentrations, scrotal circumference and % normal spermatozoa in the ejaculate peaked around September. Testosterone levels fell sharply by November, but scrotal circumference declined less sharply and normal sperm production occurred until March. There were indications of a secondary peak in these values around February-March.

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Section: Discussionmentioning

confidence: 93%

Relationships between seasonal changes in serum testosterone concentrations, scrotal circumference and sperm morphology of male wapiti (Cervus elaphus)

Haigh¹,

Cates²,

Glover³

et al. 1984

Reproduction

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“…The early lambs were slaughtered in July and the late lambs at the beginning of December. British sheep breeds, including the Suffolk, are known to respond to shorter daylight length, showing greater sex drive (Chang, 1945;Cupps, McGowan, Rahlmann, Reddon & Weir, 1960;Lees, 1965). Ortavant, Mauléon & Thibault (1964) have published results showing a higher fructose concentration in the seminal vesicles of rams exposed to short daylight hours and Cupps et al (1960) found fructose concentration in the ejaculate reached a maximum in Suffolks in October.…”

Section: Discussionmentioning

confidence: 99%

Puberty in Suffolk and Cross-Bred Rams

Skinner¹,

Rowson²

1968

Reproduction

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Changes during puberty were studied in the live ram lamb by collecting electro-ejaculates and measuring fructose and citric acid concentration and sperm density and morphology. Fructose and citric acid secretion preceded spermatogenesis. Sperm motility improved with decreasing numbers of abnormal spermatozoa. Observations are included on the separation of the penis from the prepuce. In addition, the influence of season of birth on lamb ejaculates was studied. Reproductive development in lambs born in late summer was delayed, androgen secretion being more markedly affected than spermatogenesis.The results of these studies support the view that the onset of male puberty coincides with the time when the testes become androgenically active, the accessory glands begin to secrete fructose and citric acid, and the animal exhibits characteristic male behaviour. to study the effect of birth date on sexual function. Six of these lambs were born in February/March, and will be referred to as spring lambs, and six were born in July/August and will be referred to as late summer lambs. Data from six mature Suffolk rams have been included for comparison. The lambs were weaned at 3 \ months when supplementary creep feeding was provided at a rate of ¿ lb pelleted concentrates per day (Diet 302, BOCM Ltd).Semen was collected by electrical stimulation (Rowson & Murdoch, 1954) at weekly intervals, using a polypropylene probe 25 cm long and 2 cm diameter, with four embedded brass electrodes, 7 cm long and 0-5 cm wide, alternately connected; the probe was inserted to a depth of about 12 cm inside the anus. Attempts to collect semen by electro-ejaculation were made from 30 days of age onwards. In the spring lambs, Suffolk and cross-bred, these attempts were successful at 42 days of age but in the late summer lambs not until 63 days of age. The total ejaculate was obtained, the appearance noted and volume recorded at weekly intervals.Immediately after collection, a sample of semen was examined under the microscope for the presence of spermatozoa and to observe their motility. If no spermatozoa were present the ejaculate was frozen in solid C02. When spermatozoa first appeared samples were taken after complete ejaculation for nigrosin-eosin staining (Campbell, Dott & Glover, 1956) and haemocytometer counts. When sperm density increased, the bulk of the ejaculate was collected into test tubes in dry ice but a small volume was collected into a separate tube for staining and counting. The percentage of live spermatozoa was determined from the nigrosin-eosin stained slides as well as the morphologi¬ cal abnormalities as classified by Blom (1950).Fructose and citric acid determinations were carried out according to the methods of Roe (1934) and Speck, Moulder, & Evans (1946), respectively, as modified by Mann (1946Mann ( , 1964 and Mann, Davies & Humphrey (1949). Estimations were made on samples of seminal plasma after centrifugation to remove the spermatozoa so that the estimates were made on the same volume of seminal plasma in each case.Obs...

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“…La histologia testicular relacionada con la epoca del afio, muestra que durante el anestro la espermatogenesis se disminuye y en ocasiones desaparece en la mayoria de los rubulos seminiferos, pocos tubos contienen espermatozoides maduros (CuPPS et al, 1960). Algunas de las celulas espermatogcnicas pueden mostra cambios degenerativos, con una gran disminuci6n en el nurnero de las celulas de Leydig.…”

Section: Introductionunclassified

La Función Endócrina del Testículo en el Carnero Criollo Mexicano Durante las Diferentes Epocas del Año y su Control Opioidergico Durante el Anestro

Fuentes

Sánchez

González

et al. 1997

Journal of Veterinary Medicine Series A

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Summary This work was carried out with the objective of studying the endocrine function of the testes in the Mexican Crossbred Ram (Suffolk × Hampshire) during the different seasons of the year in a latitude of 19°13′N. Also studied was the opioidergic control of this gland during anoestrus. For this purpose 8 rams were used, from which 3 ml of jugular blood were obtained three times a week to study the seasonal fluctuations in plasma testosterone. The experiment was carried out from May 1993 until June 1994. The androgen was determined by radioimmunoassay. To study the opioidergic control of androgen secretion during seasonal anoestrous (May—June) four of the rams were selected at random and treated with 0.5 mg naloxone at 12 h intervals during 3 continuous weeks. It was observed that blood testosterone was lowest during long days, and concentration was highest during the breeding season. Chronic naloxone medication during anoestrus resulted in a significant increase in blood testosterone (P < 0.001), an effect that was evident after the first week of treatment. When naloxone administration was discontinued, blood testosterone levels returned to basal. With this experiment it was demonstrated that an opioid antagonist such as naloxone administered in low doses, is capable of altering plasma testosterone concentration in the anoestrus ram, giving further support to endogenous opioids as important modulators of reproduction in seasonal breeders such as sheep. Resumen Con el proposito de estudiar la función endócrina del testículo en el carnero criollo mexicano (Suffolk × Hampshire) a una latirud de 19° 13′ N; y asimismo tambien estudiar su control opiodergico durante la epoca de anestro. Se utilizaron 8 carneros machos de los cuales se obtuvieron muestras sanguineas tres veces por semana para deterrninar las concentraciones de testosterona por radio immunoanálisis desde mayo de 1993 hasta junio de 1994. Durante el periodo de anestro estacional; del grupo de ocho; se escogieron al azar cuatro borregos, y fueron medicados con 0.5 mg/12 horas de naloxona durante tres semanas. La concentración sanguinea de testosterona mostró una variación circanual, con los niveles hormonales mas bajos durante el fotoperiodo largo; y los mas altos durante la época de empadre. La medicación crónica con naloxona incrementó significativamente (p < 0.001) los niveles sanguíneos de testosterone, efecto que se hizo evidente hasta la segunda semana de tratamiento. Al descontinuar la administración del antagonista opioide los niveles sanguíneos de testosterona regresaron a los niveles basales iguales a los del grupo no medicado. Este experimento demuestra que dosis bajas del antagonista opioide naloxona pueden modificar los patrones endócrines reproductivos de los animales poliestricos estacionales, como la oveja y respalda el postulado de que los opioides endógenos estan jugando un papel importante en la reproducción de los animales domésticos.

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Seasonal Changes in the Semen of Rams

Cited by 29 publications

References 3 publications

Relationships between seasonal changes in serum testosterone concentrations, scrotal circumference and sperm morphology of male wapiti (Cervus elaphus)

Relationships between seasonal changes in serum testosterone concentrations, scrotal circumference and sperm morphology of male wapiti (Cervus elaphus)

Puberty in Suffolk and Cross-Bred Rams

La Función Endócrina del Testículo en el Carnero Criollo Mexicano Durante las Diferentes Epocas del Año y su Control Opioidergico Durante el Anestro

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