Urinary androgen concentrations and social status in two species of free ranging zebra (Equus burchelli and E. grevyi)

Chaudhuri, M.; Ginsberg, Joshua R.

doi:10.1530/jrf.0.0880127

Cited by 12 publications

(7 citation statements)

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“…These observations are in agreement with the data reported by Kirkpatric, et al [10] who showed that testosterone concentration of bachelor stallions was significantly lower than of stud stallions. These results are consistent with the hypotheses that the presence of females may be a social stimulus influencing testosterone secretion [3], and that individual differences in harem size among feral stallions may be influenced by testosterone concentration, which affect the reproductive success of stallions. However, there may be many complex factors involved in determining harem size, such as avoidance of the parent-child relationship, strength of aggression of males, mental factor of mares.…”

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confidence: 90%

“…These males were still immature with a reduced libido, which is consistent with the results of Chaudhuri and Ginsberg [3] who noted that males that have access to females, excrete more androgen than non-breeding males. Whereas, mature stallions (3 years or older), have a seasonal pattern of testosterone concentrations which were significantly higher in the breeding than the non-breeding season (p<0.01).…”

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confidence: 90%

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Relationship between Plasma Testosterone Concentrations and Age, Breeding Season and Harem Size in Misaki Feral Horses.

Khalil

Murakami

Kaseda

1998

The Journal of Veterinary Medical Science

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ABSTRACT. Jugular vein blood samples were collected from 23 young and sexual mature feral stallions to examine the relationship between plasma testosterone concentration and age, breeding season or harem size. Testosterone concentration increased with the age of the stallions until they formed their own harems, at about 4 to 6 years old. Seasonal variations in testosterone concentrations were observed, and found to be significantly higher (P<0.001) throughout the breeding season than non-breeding season, from 3 years of age. Testosterone levels were correlated with harem size for individual stallions. It can be inferred from these results that there is a relationship between plasma testosterone concentration and age, breeding season and harem size. -KEY WORDS: equine (wild), harem, testosterone.J. Vet. Med. Sci. 60(5): 643-645, 1998 Fresh water ponds are plentiful in the range. The grasslands are restricted to the upper area (about 40 ha) half way up the two hills (about 290 m above sea level) which are located in the center of the range and covered with various kinds of native grasses. Other areas of the range are mostly occupied by artificial forests with Japanese cedars and a variety of copses [8]. Generally, the warm climate and abundant rain provide a lot of vegetation in summer. In the first experiment, twenty-three feral male horses, ranging from 1 to 6 years of age, were used to determine the relationship between testosterone levels and age, or breeding season. All animals were in good physical conditions during the experiment. Individual horses were readily identified by the number branded on the hip. Almost Misaki horses were individually recorded the birth date and parents (identified by DNA analysis). Blood samples were collected four times every two weeks from 23 individual horses in May and June of 1994, and mean values of testosterone for each were obtained. These data was used to relate testosterone concentrations to age for the breeding season. Similarly blood samples were collected four times every two weeks in October and November of 1994, to provide data for the non-breeding season.In the second experiment, we randomly selected 7 males at different ages (4-9 years old) with or without a harem, and examined the change of harem size and testosterone levels during two Breeding seasons from 1993 to 1995, in order to investigate their relationship. Blood samples were collected from the 7 individual males in May of both 1994 and 1995 and harem formation was observed. The horses were extremely dangerous to handle and were restrained with Xylazine as recommended by Dodman [5]. A dose of 4 mg/kg body weight was injected using a special syringe, fired from a blowgun at a few meters from the horse (hind quarter), for accuracy. Some of the horses never adjusted to the restraint procedures and so we tried again on other days. Blood samples were taken by jugular vene puncture into heparinised tubes and placed on ice, plasma was obtained by centrifugation and was stored at 20°C until Testosterone is the ...

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confidence: 90%

supporting

confidence: 90%

Relationship between Plasma Testosterone Concentrations and Age, Breeding Season and Harem Size in Misaki Feral Horses.

Khalil

Murakami

Kaseda

1998

The Journal of Veterinary Medical Science

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“…Sperm production is proportional to testis size (Willet and Ohms 1957) and in various ways to the presence of elevated levels of testosterone (van Tienhoven 1983), and the amount actually delivered is proportional to the number of ejaculations. In both species of zebra, breeding stallions have been shown to maintain higher levels of testosterone when compared with non-breeding males (Chaudhuri and Ginsberg 1989). Relatively larger testes have been found in promiscuous species of primates (Harcourt et al 1981), cervids (Clutton-Brock et al 1983), and mammals from elephants to mice (Kenagy and Trombulak 1986).…”

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confidence: 99%

Sperm competition and variation in zebra mating behavior

Ginsberg

Rubenstein

1990

Behav Ecol Sociobiol

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Data are presented on the breeding behavior of two zebra species to test whether intra-and interspecific variation in male reproductive behavior and physiology are correlated with differences in female promiscuity. In one species, plains zebra (Equus burchel-I/) females live in closed membership single male groups and mate monandrously. In the other species, the Grevy's zebra (E. grevyi) females live in groups whose membership is much more temporary. Typically, associations with individual males are brief and mating is polyandrous. However, some females -those having just given birth -reside with one male for long periods, mating monandrously. These differences in female mating behavior generate variability in the potential for sperm competition. We show that behavioral differences in male investment in reproductive activities correlate with the potential for sperm competition. When mating with promiscuous mares, Grevy's zebra stallions made a greater investment in reproductive behavior (calling, mounting, ejaculations) than did stallions of either species when mating with monandrous females. The evolution of large testes size in the Grevy's zebra, when compared to the congeneric plains zebra, horse, and moun: tain zebra, allows for this increased investment.

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“…Moreover, stress caused by capture and administration of an anesthetic agent can affect hormone levels in the blood [7,8]. Hormone levels have been measured in materials other than blood, such as feces, milk, saliva and urine [9][10][11][12][13][14]. Of these sources, feces can be collected conveniently and noninvasively, and hormone levels in feces from a wide variety of wild animals have been investigated to investigate their reproductive functions [15][16][17][18][19][20].…”

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confidence: 99%

Plasma and Fecal Sex Steroid Hormone Profiles During the Estrous Cycle in a Japanese Serow (Capricornis crispus)

Togashi

Tsujimoto²,

Yamauchi

et al. 2009

Journal of Reproduction and Development

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Abstract. We aimed to determine plasma progesterone and estradiol-17β concentrations, as well as fecal progesterone concentrations during the estrous cycle in a female 8-year-old Japanese serow (Capricornis crispus). The step frequencies during the night were recorded by a pedometer attached to the serow's hind leg from October to the following June. Estrous behavior was also monitored during the day. Blood samples were taken once a day from 8 February to 10 March from an indwelling catheter placed in the jugular vein. Fecal samples were taken once or twice a day from 1 January to 29 April. Plasma and fecal progesterone and plasma estradiol concentrations were determined using timeresolved fluoroimmunoassays. The estrus behavior observed lasted for 2-3 days. Peak step frequencies were recorded between November and April, at intervals of 17-19 days. Plasma progesterone concentrations remained elevated (1-7.7 ng/ml) for 12 days during non-estrus, and plasma estradiol concentrations were highest when the peak step frequency and estrous behavior were observed.Step frequency increased around the times fecal progesterone levels fell to basal levels. Progesterone concentrations in feces were significantly correlated with those in sera. Thus, measurement of fecal progesterone concentrations might be useful for monitoring the reproductive status of the Japanese serow.

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Urinary androgen concentrations and social status in two species of free ranging zebra (Equus burchelli and E. grevyi)

Cited by 12 publications

References 12 publications

Relationship between Plasma Testosterone Concentrations and Age, Breeding Season and Harem Size in Misaki Feral Horses.

Relationship between Plasma Testosterone Concentrations and Age, Breeding Season and Harem Size in Misaki Feral Horses.

Sperm competition and variation in zebra mating behavior

Plasma and Fecal Sex Steroid Hormone Profiles During the Estrous Cycle in a Japanese Serow (Capricornis crispus)

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