[Level of plasma testosterone in relation to age, gonad size and sexual libido in bulls].
The level of plasma testosterone (PT) was determined by the direct RIA method with tritium-labelled testosterone. An average level of 2.25 +/- 1.46 nmol PT/l was found in 57 bullocks old 47 to 106 days. Until the age of 67 days, the level of PT was 1.11 +/- 0.69 nmol/l and from the 68th to the 110th day 2.74 +/- 1.32 nmol. In the period from the 7th to the 13th month of age, 108 bulls were found to have the PT level of 23.04 +/- 19.81 nmol/l, which was a statistically significant increase (P = 0.01) as compared with the prepubertal period. In 154 bulls old two years and older, the PT level was found to be 21.72 +/- 14.78 nmol/l. In comparison with bulls old 7 to 13 months, no statistically significant difference was recorded in PT levels. Neither was found any correlation between the gonad size and PT level and any relation between libido and PT level. In the bulls having no libido the PT level was insignificantly higher than in the bulls with pronounced libido sexualis. In all the studied groups of bulls, a comparatively high variation was found in PT values.
D000367:Age Factors; D000818:Animals; D001699:Biometry; D002417:Cattle / Q000502:physiology*; D008297:Male; D012726:Sexual Behavior, Animal; D013737:Testis / Q000033:anatomy & histology*; D013739:Testosterone / Q000097:blood*
D013739:Testosterone
Hladina plazmatického testosteronu ve vztahu k vĕku, velikosti gonád a libido sexualis býků.