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Parameters for Seasonally Breeding Populations
Ecology, 1967Lotka's equations relating the parameters of populations with no seasonal trend in birth rates and Fisher's formula for "reproductive value" are modified to describe populations with restricted annual seasons of birth. The parameters "net reproductive rate" and "mean generation length" provide statistics and dubious utility for populations with ...
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Out-of-Season Breeding in Goats
Veterinary Clinics of North America: Food Animal Practice, 1990Maintenance of winter milk production and the production of meat kids for seasonal specialty markets are two major reasons for out-of-season breeding. Strategies include the manipulation of light cycles and the administration of exogenous gonadotrophins following progestogen priming with either vaginal sponges or subcutaneous implants. A number of does
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Breed Differences in the Breeding Season in Sheep
1985The literature has been surveyed for evidence of genetic variation in sexual function of rams throughout the year and in the timing of onset and duration of the breeding season in female sheep. The results of studies on the breeding season of several ewe breeds in Ireland are also presented.
J. F. Quirke, J. P. Hanrahan
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Kisspeptin: A key link to seasonal breeding
Reviews in Endocrine and Metabolic Disorders, 2007In seasonal species, photoperiod (i.e. daylength) tightly regulates reproduction to ensure that birth occurs at the most favorable time of year. In mammals, a distinct photoneuroendocrine circuit controls this process via the pineal hormone melatonin. This hormone is responsible for the seasonal regulation of reproduction, but the anatomical substrate ...
Florent G, Revel +6 more
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Inherent seasonality in the breeding seasons of African mammals: evidence from captive breeding
Transactions of the Royal Society of South Africa, 2002Breeding records from zoos provide a virtually untapped source of information for determining reproductive patterns of species unconstrained by nutritional variables and may be important in planning conservation strategies for rare species for which little “wild” data exist.
J. D. SKINNER, D. G. MOSS, D. C. SKINNER
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BREEDING SEASONS IN THE GALAPAGOS.
Ibis, 1950Summary. The Galapagos are on the equator. In the cool and cloudy dry season the south‐east trade wind blows and the cold Humboldt current flows strongly round the islands. In the rainy season, which is very variable but usually lasts from about January to April, the weather is calm, warm and sunny, with periodic heavy rain, while the northern ...
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Nature, 1937
IT has recently been shown by Marshall and Bowden1 that not only duration but also intensity of illumination can affect the onset of a breeding season, and that ultra-violet as well as visible light is effective. These discoveries have an important bearing on seasonal phenomena in the tropics.
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IT has recently been shown by Marshall and Bowden1 that not only duration but also intensity of illumination can affect the onset of a breeding season, and that ultra-violet as well as visible light is effective. These discoveries have an important bearing on seasonal phenomena in the tropics.
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THE DURATION OF THE BREEDING SEASON OF FOUR BREEDS OF SHEEP
Canadian Journal of Animal Science, 1974Three breeds of sheep (Dorset, Leicester, and Suffolk) and a crossbred line from these breeds (DLS) were observed throughout 1 yr to determine their sexual activity by daily exposure of the ewes to vasectomized rams. The DLS and Dorset ewes exhibited their first estrus earlier in the year (P < 0.01) and stopped cycling later than the Leicester and ...
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On the breeding season in the sheep
The Journal of Agricultural Science, 1944Ewes. There was some variation from year to year in the times of onset and end of the breeding season; on the average it was evenly spaced on either side of the shortest day. Occasionally ewes were served and became pregnant at times well outside the normal limits of the breeding season.
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Seasonal Variation in the Breeding Activity of Rams
Nature, 1965MOST investigations into the breeding season, of sheep in Britain have been concerned with the behaviour of females. Little attention has been paid to the desire or ability of males to mate at different times of the year, for it is generally considered that under temperate conditions there is no discernible non-breeding season in rams of the British ...
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