PERIPHERAL PLASMA TESTOSTERONE CONCENTRATIONS IN BULLS AROUND PUBERTY

Puberty in beef bulls: hormone concentrations, growth, testicular development, sperm production and sexual aggressiveness in bulls of different breeds.

Postweaning growth and pubertal traits were studied in Hereford, Angus, Red Poll, Brown Swiss, Hereford-Angus crossbred (HXA) and Angus-Hereford crossbred (AX H) bulls from 7 through 13 months of age. Pubertal factors characterized included body weight, testicular size, hormone concentrations, sexual aggressiveness and sperm production. Puberty was defined as the age at which a bull first produ...

Relationships between short-term variations of LH, FSH, prolactin and testosterone in peripheral plasma of prepubertal bulls.

In 2 prepubertal bulls 10-min blood samples collected during a 24-h period showed that gonadotrophin and testosterone peaks occurred regularly at intervals of 6h in one animal and 8h in the other. There was a clear relationship between the LH, FSH and testosterone peaks. The increase of gonadotrophin levels was followed 20 +/- 6 (s.d.) min later by an increase of testosterone; the interval betw...

Puberty in beef bulls: acrosome morphology and semen quality in bulls of different breeds.

Semen characteristics were evaluated every 2 wk from 7 through 13 mo of age in 31 beef bulls representing six breed groups (Hereford, Angus, Hereford x Angus crossbreeds, Angus x Hereford crossbreds, Red Poll and Brown Swiss). Breeds differed in age at puberty, defined as the age at which an ejaculate was first obtained that contained a minimum of 50 x 10(6) total spermatozoa with at least 10% ...

Relation between growth rate, serum somatomedin and plasma testosterone in young bulls.

Twenty "Red Danish" bulls were tested for rate of gain, linear growth, longissimus muscle area and efficiency of feed utilization from the age of l 'h to 12 months. These variables were correlated to blood concentrations of testosterone and somatomedin, which were measured at 4 to 5 months, 6 to 7 months and/or 8 to 10 months of age. Average testosterone concentrations of bulls above 6 months o...

Testicular Development and Onset of Puberty in Beef Bulls