Volatile substances in feces, urine and urine-marked feces of feral horses

The identity and amount of volatile substances in the feces, urine and feces scent-marked with urine (i.e., feces mixed with urine) of feral horses was determined by acid/steam distillation and gas chromatography–mass spectrometry. The frequency of excretion and scent marking, as evaluated in the breeding and non-breeding seasons, showed clear evidence of seasonal behavioral differences. The concentration of each substance (fatty acids, alcohols, aldehydes, phenols, amines and alkanes) in the feces differed according to maturity, sex and stage in the reproductive process. They had a characteristic chemical fingerprint. Although the levels of tetradecanoic and hexadecanoic acids in the feces of estrous mares were significantly higher than the respective levels in the feces of non-estrous mares, in the case of scent-marked feces by stallions, the levels of them in the feces from estrous mares had decreased to levels similar to those in non-estrous mares. The concentration of these substances in mares were not significantly different. The presence of a high concentration of cresols in the urine of stallions in the breeding season suggests that one role of scent marking by stallions is masking the odor of the feces produced by mares. Key words: Odors (volatile), excrement, scent-marking, masking, horse (feral), (releaser) pheromone

17α,20β-Dihydroxy-4-pregnen-3-one: a steroidal primer pheromone increasing milt volume in the goldfish, Carassius auratus

The volume of milt that could be stripped from male goldfish, Carassius auratus, increased dramatically when fish were exposed overnight to water with concentrations of 17α,20β-dihydroxy-4-pregnen-3-one (17,20P) as low as 10−10 M. A variety of free steroids (pregnenolone, androstenedione, testosterone, 11-ketotestosterone, 17β-estradiol) and glucuronated steroids (etiocholanolone glucuronide, testosterone glucuronide, 17β-estradiol glucuronide), suggested by others to function as pheromones in fish, failed to increase milt volume at a concentration of 5 × 10−9 M. The milt response appears to be specific to 17,20P and progesterone precursors (17α-hydroxyprogesterone, progesterone), but is most sensitive to 17.20P. Because bilateral section of the olfactory tracts completely blocked the milt response to 17.20P, it is believed to be a pheromone. Selective sectioning of the lateral and medial subdivisions of the olfactory tracts demonstrated that the milt response to 17,20P is dependent on the medial tract. Increases in milt in response to 17,20P are not affected by interaction with conspecifics; exposure to 17,20P induced equivalent responses in males held in isolation, paired with a male, or paired with a female. It is proposed that 17,20P, which is produced during oocyte final maturation in the female, is a "primer" pheromone released to the water and that it increases milt volume in the male. This effect is discussed in relation to releaser pheromone effects previously demonstrated in goldfish.