
TY  - JOUR
A1  - Post, TB 
A1  - Bindon, BM 
T1  - Plasma Luteinizing Hormone and Testosterone Concentrations in Different Breeds of Young Beef Bulls in the Tropics
JF  - Australian Journal of Biological Sciences
JO  - Aust. Jnl. Of Bio. Sci.
Y1  - 1983
VL  - 36
IS  - 6
SP  - 545
EP  - 550
KW  - 
UR  - https://doi.org/10.1071/BI9830545 
N2  - Plasma concentrations of luteinizing hormone (LH) and testosterone were measured at 3, 8 and 11 months of age in 48 Africander cross (AX), 24 Brahman cross (BX), 21 Hereford-Shorthorn, selected (HSS) and 14 Hereford-Shorthorn, random-bred (HSR) bulls. In all breeds plasma LH was lower (P<O· 01) at 8 months (1·7 ng/ml) than at 3 months (2·6 ng/ml) or at 11 months (2·6 ng/ml). Over all ages there were no differences among breeds in mean plasma LH (AX 2·4, BX 2·4, HSS 1·8, HSR 2·2 ng/ml) and no breed X age interactions. In contrast, plasma testosterone increased significantly (P<O· 01) with age and at a faster rate in the AX breed, resulting in a significant (P<O· 05) breed X age interaction. Testosterone concentrations, though similar among breeds at 3 months of age (0·45 ng/ml), were much higher (P<O· 01) by 11 months in AX (2·56 ng/ml) than in BX (1·30 ng/ml), HSS (0·78 ng/ml) or HSR (0·66 ng/ml) bulls. 
ER  -

