STUDIES ON THE DURATION OF THE BREEDING SEASON AND PHOTOREFRACTORINESS IN FEMALE FERRETS PINEALECTOMIZED OR TREATED WITH MELATONIN

1976 ◽  
Vol 70 (2) ◽  
pp. 255-262 ◽  
Author(s):  
PENELOPE A. THORPE ◽  
J. HERBERT
Keyword(s):  
Pineal Gland ◽  
Breeding Season ◽  
Prolonged Exposure ◽  
Breeding Cycle ◽  
Summer Solstice ◽  
Short Days

SUMMARY Oestrous ferrets became anoestrous on exposure to short photoperiods (8 h light: 16 h darkness, 8L:16D) at the summer solstice, and this effect was prevented by pinealectomy. Removal of the pineal alone did not alter the duration of oestrus in animals kept in natural daylight. Melatonin (1 mg, thrice weekly) given to oestrous ferrets kept in daylight also terminated oestrus prematurely. Animals made photorefractory by prolonged exposure to long photoperiods (14L:10D) became photosensitive again if either given melatonin or transferred to short photoperiods (8L:16D) for 7 weeks. These findings show that the pineal gland of the oestrous ferret is involved in the termination of oestrus when the animal is exposed to experimental short photoperiods. This is in addition to its role in inducing oestrus when anoestrous animals are exposed to long days, an effect shown previously. Thus, neither phase of the annual breeding cycle is altered by experimental lighting regimes in pinealectomized animals. Furthermore, some of the effects of short days (but not of long days), including that on photosensitivity, can be replicated by melatonin in the ferret.

Effect of melatonin implants on reproductive performance in ewes

1988 ◽  
Vol 1988 ◽  
pp. 51-51
Author(s):  
W. Haresign ◽  
A.R. Peters ◽  
G.M. Webster ◽  
J.W.B. King ◽  
L.D. Staples
Keyword(s):  
Pineal Gland ◽  
Breeding Season ◽  
Reproductive Performance ◽  
Present Experiment ◽  
Reproductive Activity ◽  
Breeding Cycle ◽  
Melatonin Secretion ◽  
Neural Signal ◽  
Retinal Photoreceptors ◽  
Subcutaneous Implant

It has been known for many years that the annual breeding cycle of the sheep is controlled by photoperiod. More recently it has become apparent that this process involves the pineal gland. Light is effectively monitored by retinal photoreceptors within the eye which transmit a neural signal to the pineal gland, and this in turn responds by secreting melatonin during the period of darkness. As daylength decreases in the autumn, the duration of elevated melatonin secretion increases, and this changing ratio of high:low melatonin during each 24h period stimulates breeding activity.Both timed (by afternoon feeding or injection) and continuous (by subcutaneous or vaginal implant) administration of exogenous melatonin to ewes in mid-summer have recently been shown to mimic the effects of decreasing photoperiod by advancing the onset of the breeding season. The present experiment was undertaken to investigate the ability of a subcutaneous implant of melatonin to manipulate reproductive activity of ewes under field conditions in the U.K.

Breeding biology and movements of Australian sea-lions, Neophoca cinerea, off the west coasst of Western Australia

1992 ◽  
Vol 19 (4) ◽  
pp. 405 ◽  
Author(s):  
NJ Gales ◽  
AJ Cheal ◽  
GJ Pobar ◽  
P Williamson
Keyword(s):  
Breeding Season ◽  
Western Australia ◽  
West Coast ◽  
Metropolitan Region ◽  
Breeding Cycle ◽  
Sea Lion ◽  
The West ◽  
Breeding Sites ◽  
Sea Lions ◽  
Neophoca Cinerea

The Australian sea-lion, Neophoca cinerea, has a 17-18-month breeding cycle on islands off the west coast of Western Australia. Buller, North Fisherman and Beagle Is are the main pupping sites, with several very small colonies (n> 3) at the Abrolhos Is. The 4-5-month pupping seasons are synchronised at North Fisherman and Beagle Is, but the sea-lions from Buller I. breed one month later and those from the Abrolhos Is two months earlier. Pup production and pup mortality were highly variable between seasons over which observations were recorded: 129 pups were born at the main breeding sites in early 1988, the mortality in the first five months was 7.1%, whereas 181 pups were born in late 1989 of which 24.3% died. Pups remain in the vicinity of their natal islands for the first 4-5 months of life before leaving, perhaps on foraging trips, with their mothers. Most return to their natal island, although others haulout on islands up to 27 km away. Some male N. cinerea congregate in bachelor colonies on islands adjacent to the Perth metropolitan region during the non-breeding season and migrate up to 280 km north each breeding season. The status of the isolated, west-coast N. cinerea population is unknown. The current high level of human pressure on sea-lion terrestrial habitats and their food resources indicate a need for further monitoring of this species.

scholarly journals Effects of Oestradiol on Plasma Concentrations of Luteinizing Hormone in Ovariectomized Ewes with Clover Disease

1983 ◽  
Vol 36 (3) ◽  
pp. 295 ◽  
Author(s):  
NR Adams ◽  
GB Martin
Keyword(s):  
Luteinizing Hormone ◽  
Breeding Season ◽  
Intravenous Injection ◽  
Intramuscular Injection ◽  
Prolonged Exposure ◽  
Plasma Concentrations ◽  
Oestradiol Benzoate ◽  
Baseline Levels ◽  
The Difference ◽  
Clover Pasture

The effects of oestradiol on plasma luteinizing hormone (LH) concentrations were examined in 15 ovariectomized control ewes and 15 similar ewes with permanent infertility after prolonged grazing on oestrogenic clover pasture ('clover disease'). Before treatment, the plasma concentrations of LH were similar in the control and affected ewes. After intravenous injection with 40 pg oestradiol-I 7 p during the anoestrous season, the decline in LH concentration was greater in the clover-affected ewes and the subsequent elevation above original baseline levels was smaller. After intramuscular injection with 15 or 30 pg oestradiol benzoate during the normal breeding season, fewer clover-affected ewes showed a surge of LH, and the response was both reduced and retarded. This difference between the two groups has not been observed in studies on intact ewes, and it is suggested that in intact ewes the difference is masked by a greater tonic LH activity in affected ewes. The results of the present study are consistent with the hypothesis that prolonged exposure to oestrogenic pasture has a differentiating, or 'androgenizing' effect on the adult ewe.

Light and the pineal gland in the control of the breeding season in the female ferret

1975 ◽  
Vol 19 (4) ◽  
pp. 280-281 ◽  
Author(s):  
J. Herbert ◽  
P. A. Thorpe ◽  
M. Klinowska
Keyword(s):  
Pineal Gland ◽  
Breeding Season

scholarly journals Aspects de la Dynamique des Populations Chez un Isopode Interstitiel

1981 ◽  
Vol 51 (1) ◽  
pp. 20-30 ◽  
Author(s):  
Nicole Coineau
Keyword(s):  
Population Structure ◽  
Breeding Season ◽  
Western Mediterranean ◽  
Breeding Cycle ◽  
Embryological Development ◽  
Maximum Life Span ◽  
Dynamique Des Populations ◽  
Reproduction Season ◽  
Increasing Temperature ◽  
Interstitial Waters

A study of the breeding cycle and population structure of Angeliera phreaticola (Isopoda, Asellota, Microparasellidae) has been carried out in the western Mediterranean. The species shows a seasonal reproductive cycle. The breeding season occurs from mid-April to the end of September. Release of juveniles is limited to the period from June to the end of September. Fourty to seventy days are necessary for the embryological development which is very long, eighty days for the post-marsupial one. It is suggested that in spring the increasing temperature of the interstitial waters accelerates the maturity of the ovocyte and post-embryonic development, and causes an advance of the breeding season. Each summer-born generation reproduces next year and yields reproducing animals two years after. Each female produces two broods (rarely three) per reproduction season and can get three to six descendants at most. Sex ratio of males to females is expressed as a function of the season and the size; males outnumber females. A. phreaticola has a maximum life span of about two years and two or three months.

INITIAL OBSERVATIONS ON PINEALECTOMIZED FERRETS KEPT FOR LONG PERIODS IN EITHER DAYLIGHT OR ARTIFICIAL ILLUMINATION

1972 ◽  
Vol 55 (3) ◽  
pp. 591-597 ◽  
Author(s):  
J. HERBERT
Keyword(s):  
Pineal Gland ◽  
Pituitary Gland ◽  
Breeding Season ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Artificial Light ◽  
Long Day ◽  
Artificial Illumination ◽  
Second Year

SUMMARY Removal of the pineal gland from ferrets kept entirely in daylight prevented the appearance of the normal annual oestrous rhythm. Animals were operated upon in the autumn; that is, at the start of their anoestrum. Oestrus in pinealectomized ferrets began at the usual time the following spring, as in control-operated and normal animals. However, during the second year after operation, pinealectomized ferrets came into oestrus 20–30 weeks after controls. Mean intervals between onsets of successive oestrous periods were: pinealectomized, 73·8 weeks (4 animals); control-operated, 52·9 weeks (7 animals); and normal animals, 52·5 weeks (10 animals). The duration of the oestrous period was not altered by removing the pineal. Three other pinealectomized ferrets kept in artificial photoperiods (14 h light: 10 h darkness) showed an oestrous rhythm indistinguishable from those pinealectomized and kept in daylight, whereas four controls that had also been put into artificial light showed greatly prolonged oestrous periods lasting more than a year. These experiments indicate that the pineal is concerned with timing the annual breeding season of ferrets in natural daylight as well as in artificial illumination. The anterior pituitary gland of pinealectomized ferrets seems unresponsive to either natural or artificial light under the conditions used in these studies. The duration of oestrus may be self-limited, but can be prolonged if the pineal gland is stimulated by the artificial 'long day'.

scholarly journals Diet specialization of Olrog's Gull Larus atlanticus during the breeding season at Golfo San Jorge, Argentina

2005 ◽  
Vol 15 (1) ◽  
pp. 89-97 ◽  
Author(s):  
GONZALO HERRERA ◽  
GABRIEL PUNTA ◽  
PABLO YORIO
Keyword(s):  
Breeding Season ◽  
Carapace Width ◽  
Breeding Cycle ◽  
Percentage Contribution ◽  
Diet Specialization ◽  
Olrog’S Gull ◽  
Main Component ◽  
Prey Items

We studied the diet of breeding Olrog's Gulls Larus atlanticus during 1994 at two colonies in Golfo San Jorge, Argentina, through the analysis of 207 regurgitated pellets. The diet at Isla Felipe and Isla Vernaci Sudoeste comprised only a few items (9 vs 7 respectively), of which crabs were the main component. At Isla Felipe, the crabs Cyrtograpsus altimanus and C. angulatus were present in 91.2% and 89.2% of pellets, respectively, while the percentage contribution of each species was 76.1% and 21.7%, respectively. At Isla Vernaci Sudoeste, the figures were similar (96.2% and 80% of pellets, and percentage contributions 79.4% and 19.5%). All other taxa were present in less than 11% of pellets. No significant differences were found between colonies in the number of prey items, prey individuals per pellet, and consumption of crabs. Percentage contribution of crabs differed significantly between stages of the breeding cycle at Isla Felipe but not at Isla Vernaci Sudoeste. At both colonies, the proportion of male C. altimanus in pellets was larger than that of females. The proportion of female C. angulatus in pellets at Isla Vernaci Sudoeste was larger than that of males, but no significant differences were found in the consumption of each sex at Isla Felipe. Mean maximum carapace width of male crabs in pellets was not significantly different from that of females at either Isla Felipe or Isla Vernaci. Our study at Golfo San Jorge confirms that Olrog's Gull is fairly specialized, feeding mainly on crabs during the breeding season.

The effect of the breeding season, cryopreservation and physiological extender on selected sperm and semen parameters of four ferret species: implications for captive breeding in the endangered black-footed ferret

2009 ◽  
Vol 21 (2) ◽  
pp. 351 ◽  
Author(s):  
G. van der Horst ◽  
R. M. Kitchin ◽  
M. van der Horst ◽  
R. W. Atherton
Keyword(s):  
Breeding Season ◽  
Sperm Motility ◽  
Captive Breeding ◽  
Assisted Reproductive Technologies ◽  
Sperm Quality ◽  
Reproductive Technologies ◽  
Semen Parameters ◽  
Breeding Cycle ◽  
Sperm Characteristics ◽  
Motion Characteristics

In the present investigation, comparative baseline information on selected sperm characteristics of ejaculate spermatozoa of the domestic (Mustela putorius furo), fitch (Mustela sp.) and black-footed ferrets (Mustela nigripes) and the Siberian polecat (Mustela eversmanni) are presented. The main emphasis was to establish differences and similarities among these species in relation to semen and sperm quality during the breeding season, in cryopreservation success and in supporting sperm motility in different extenders or physiological media. The results confirm that most sperm morphology abnormalities were evident during the beginning of the breeding cycle in all four species. No significant interspecies differences were apparent in the sperm attributes examined, for all sampling months during the breeding season. Moreover, all species exhibited comparable patterns of reproductive seasonality. Cryopreservation suppressed sperm characteristics equally in all species studied. Ejaculate spermatozoa of closely related ferret species shared many similar motion characteristics using computer-aided sperm motility analysis. These results suggest that the basic sperm physiology of the ferret species under examination is very similar. Disparate to the interspecies comparisons, there were significant differences for most sperm motion parameters when spermatozoa of any of the ferrets were compared in different extenders. Assisted reproductive technologies developed for use in domestic ferret, fitch ferret or Siberian polecat may be successfully applied to captive breeding of the black-footed ferret using semen during any of the functional breeding months.

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