Hr. Veraavila et al., EFFECT OF DIETARY PHENOLIC AMINES ON TESTICULAR FUNCTION AND LUTEINIZING-HORMONE SECRETION IN MALE ANGORA-GOATS, Journal of animal science, 75(6), 1997, pp. 1612-1620
To test the effect of dietary phenolic amines on pituitary-gonadal fun
ction, 24 postpubertal male Angora goats were assigned during the bree
ding season to a control diet or to graze on a pasture dominated by ph
enolic amine-containing vegetation (PA). Compared with control bucks,
bucks grazing PA had decreased (P < .001) serum concentrations of test
osterone, increased (P < .001) triiodothyronine (T-3) and thyroxine (T
-4), greater (P < .001) reduction in scrotal circumference (SC), lower
(P < .001) body weight gains, and reduced (P < .01) semen volume. Spe
rm concentration and progressive motility were not affected by treatme
nt. On d 75 of treatment, endogenous and GnRH-stimulated LH secretion
were greater (P < .01), but endogenous and stimulated testosterone sec
retion tended (P < .10) to be reduced in the PA bucks relative to the
controls. Endogenous serum concentrations of LK and testosterone were
positively correlated in the controls, whereas no correlation was dete
cted in the PA males. We conclude that during the breeding season, inc
reased consumption of plants with a high concentration of phenolic ami
nes can affect the reproductive competence of male goats in a manner t
hat suggests a premature ending of the active reproductive phase. The
concurrent influence of dietary phenolic amines on serum T-3 and T-4,
and the relationship of these hormones with expression of seasonal rep
roduction in domestic and wild ruminants, warrants further analysis of
the relationship between dietary phenolic amines, thyroid function, a
nd reproduction in these species.