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Seasonal variation in serum testosterone, testicular measurements and semen characteristics in the collared peccary (Tayassu tajacu). 1989

E C Hellgren, and R L Lochmiller, and M S Amoss, and S W Seager, and S J Magyar, and K P Coscarelli, and W E Grant
Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station 77843.

Blood samples and testicular measurements were obtained from 4-8 captive adult collared peccaries monthly for 18 months and from wild adult males during summer (N = 16) and winter (N = 22) seasons. Serum concentrations of testosterone were determined by radioimmunoassay. Semen samples were collected monthly by electroejaculation from captive males for 1 year. Serum testosterone concentrations and testicular measurements varied in a low-amplitude circannual pattern, with maximum mean testosterone concentrations in fall and winter (1150-1400 pg/ml) and minimum values in summer (500-700 pg/ml). Circannual rhythms appeared to be related to dominance. Serum testosterone levels in wild males generally were lower than in captive males, although this difference was not significant (P greater than 0.05). Semen characteristics did not exhibit a circannual rhythm. These results suggest that the male peccary remains reproductively fertile throughout the year, yet may undergo a facultative summer quiescence influenced by ambient temperature and social factors.

UI MeSH Term Description Entries
D008297 Male Males
D010507 Periodicity The tendency of a phenomenon to recur at regular intervals; in biological systems, the recurrence of certain activities (including hormonal, cellular, neural) may be annual, seasonal, monthly, daily, or more frequently (ultradian). Cyclicity,Rhythmicity,Biological Rhythms,Bioperiodicity,Biorhythms,Biological Rhythm,Bioperiodicities,Biorhythm,Cyclicities,Periodicities,Rhythm, Biological,Rhythmicities,Rhythms, Biological
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001188 Artiodactyla An order of mammals which consists of the even-toed ungulates and includes both RUMINANTS and SWINE. Hippopotamus,Peccary,Peccaries
D012621 Seasons Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Seasonal Variation,Season,Seasonal Variations,Variation, Seasonal,Variations, Seasonal
D012661 Semen The thick, yellowish-white, viscid fluid secretion of male reproductive organs discharged upon ejaculation. In addition to reproductive organ secretions, it contains SPERMATOZOA and their nutrient plasma. Seminal Plasma,Plasma, Seminal
D013076 Sperm Count A count of SPERM in the ejaculum, expressed as number per milliliter. Sperm Number,Count, Sperm,Counts, Sperm,Number, Sperm,Numbers, Sperm,Sperm Counts,Sperm Numbers
D013081 Sperm Motility Movement characteristics of SPERMATOZOA in a fresh specimen. It is measured as the percentage of sperms that are moving, and as the percentage of sperms with productive flagellar motion such as rapid, linear, and forward progression. Motilities, Sperm,Motility, Sperm,Sperm Motilities
D013094 Spermatozoa Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility. Sperm,Spermatozoon,X-Bearing Sperm,X-Chromosome-Bearing Sperm,Y-Bearing Sperm,Y-Chromosome-Bearing Sperm,Sperm, X-Bearing,Sperm, X-Chromosome-Bearing,Sperm, Y-Bearing,Sperm, Y-Chromosome-Bearing,Sperms, X-Bearing,Sperms, X-Chromosome-Bearing,Sperms, Y-Bearing,Sperms, Y-Chromosome-Bearing,X Bearing Sperm,X Chromosome Bearing Sperm,X-Bearing Sperms,X-Chromosome-Bearing Sperms,Y Bearing Sperm,Y Chromosome Bearing Sperm,Y-Bearing Sperms,Y-Chromosome-Bearing Sperms
D013737 Testis The male gonad containing two functional parts: the SEMINIFEROUS TUBULES for the production and transport of male germ cells (SPERMATOGENESIS) and the interstitial compartment containing LEYDIG CELLS that produce ANDROGENS. Testicles,Testes,Testicle

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