Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 1997
Publication Date: N/A
Technical Abstract: The objective of the present studies was to investigate correlated traits in boars that were divergent in FSH secretion. Body weight at castration was similar in the two groups but testicular weight was 1.7 times greater in the boars with loFSH. At 1, 2 and 8 wk of age plasma TSH concentrations were similar (P>0.10) in the two groups, but concentrations declined in the eloFSH boars during pubertal development such that at 16, 20 and 24 wk plasma TSH concentrations were greater (P<0.01) in hiFSH than in loFSH boars (1.8 vs 1.20ñ0.15 ng/ml at 24 wk). Testicular concentrations of iron and copper were positively correlated with plasma FSH concentration and negatively correlated with total testicular weight. Basal FSH concentrations were two times greater (P<0.01) in hiFSH than in loFSH boars, and FSH concentrations increased after GnRH stimulation. Concentrations of LH also increased (P<0.01) after GnRH, and maximal concentrations that were achieved after GnRH stimulation were greater (P<0.05) in hiFSH than in loFSH boars. Collectively, MS x WC boars that were selected for elevated plasma FSH concentrations had greater plasma TSH during pubertal development, smaller testes, greater LH after GnRH stimulation and greater testicular concentrations of iron and copper. Thus, boars with low FSH (larger testes) released less LH; the impact on testosterone secretion has not been evaluated fully. The association of FSH with LH re-enforces their common cell of origin, the gonadotrope, but the association with TSH was unexpected and underscores some potential role of the alpha subunit in regulation of pituitary glycoprotein hormone concentrations. The association of testicular iron and copper with color and plasma FSH remains unexplained.