Breed differences in testicular growth and gonadotropin secretion in prepubertal ram lambs.
Scrotal circumference (SC) and plasma concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured in 19 Finnish Landrace (Finn) and 29 Rambouillet crossbred ram lambs raised in confinement and in 21 Finn and 19 Dorset crossbred ram lambs raised on pasture. SC was larger (P<0.05) for Finn crossbreds than for Rambouillet crossbreds only at 70 and 100 days of age. Finn crossbreds had more (P<0.05) plasma LH and FSH than did Rambouillet crossbreds at 20 and 44 days but not at 70 days. SC was larger for Dorset crossbreds than for Finn crossbreds at the same age, but SC was larger (P<0.05) for Finn crossbreds than for Dorset crossbreds at the same weight. Finn and Dorset crossbreds differed (P<0.10) in plasma LH and FSH concentration at 77 days only (Finn>Dorset).
Lucas
J R
JR
Virginia Polytechnic Institute and State University Blacksburg, VA 24061 USA.
Notter
D R
DR
McClaugherty
F S
FS
Anderson
G W
GW
Gwazdauskas
F C
FC