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Endocrine and Testicular Changes Associated with Season, Artificial Photoperiod, And the Peri-Pubertal Period in Stallions

1992; Elsevier BV; Volume: 8; Issue: 1 Linguagem: Inglês

10.1016/s0749-0739(17)30465-0

1558-4224

Colin M. Clay, Joan N. Clay,

Effects of Environmental Stressors on Livestock

Stallions have a seasonal reproductive cycle that is characterized by annual fluctuations in testicular size and weight, sperm production and output, libido, and serum concentrations of luteinizing hormone, follicle-stimulating hormone, and testosterone. This seasonal reproductive cycle is responsive to manipulation by photoperiod such that sexual recrudescence can be hastened by the application of long days. Stallions may possess an endogenous circannual rhythm in reproductive function that is synchronized by the annual changes in day length. The peripubertal period in colts extends to 83 weeks and is characterized by low to gradually increasing gonadotropin concentrations and a marked increase in testosterone secretion at approximately the mean age of puberty.