Horn growth related to testosterone secretion in two wild Mediterranean ruminant species: the Spanish ibex (Capra pyrenaica hispanica) and European mouflon (Ovis orientalis musimon).
Seasonal variations in the horn development and testicular activity of the Spanish ibex (Capra pyrenaica hispanica) (n=6) and European mouflon (Ovis orientalis musimon) (n=5) were monitored to determine the role of increasing testosterone concentration on the arrest of horn growth during the rutting season. Marked seasonal variations in the rate of horn growth (P<0.01) and testicular activity (P<0.001) were seen in both species, although the magnitude and timing of these changes were different (P<0.01). Horn growth rate was inversely correlated to seasonal levels in testosterone plasma concentration in both species (ibex: R=-0.45, P<0.01; mouflon R=-0.51, P<0.01). In the mouflon, the increase in plasma testosterone concentration recorded in September (P<0.05 compared with the lowest concentration) coincided with a significant reduction in horn growth (P<0.05). In the ibex, the increase in plasma testosterone concentration in October (P<0.05 compared with the lowest concentration) was associated with a significant arrest of horn growth in November (P<0.05). These results appear to support the hypothesis that high peripheral plasma levels of testosterone are linked with the seasonal arrest of horn growth during the rutting period.
Toledano-Díaz
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A
Dpto. Reproducción Animal, SGIT-INIA, Avda. Puerta de Hierro Km 5.9, 28040 Madrid, Spain. toledano@inia.es
Santiago-Moreno
J
J
Gómez-Brunet
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A
Pulido-Pastor
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A
López-Sebastián
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A
D000818:Animals; D006041:Goats / Q000502:physiology*; D006733:Horns / Q000254:growth & development*; D008297:Male; D019083:Mediterranean Region; D012611:Scrotum / Q000033:anatomy & histology; D012621:Seasons; D012756:Sheep / Q000502:physiology*; D013739:Testosterone / Q000097:blood / Q000378:metabolism*
D013739:Testosterone