COORDINATE PATTERN OF SECRETION OF LUTEINIZING-HORMONE AND TESTOSTERONE IN MATURE MALE TURKEYS UNDER CONTINUOUS AND INTERMITTENT PHOTOSCHEDULES

Secretory patterns of luteinizing hormone (LH) and testosterone (T) we re determined in sexually mature male turkeys housed under Continuous [14 h light (L):10 h dark (D), n = 3)] or Intermittent [8 x (1L:2D), n = 3] photoschedules. Jugular vein cannulas were implanted on Day 0 an d serial blood samples were taken at 5-min intervals for 12 h on Day 3 and again 4 to 7 d later. Most increases in T concentration were prec eded by an increase in LH concentration for both photoschedules. Treat ment differences for overall mean T [1.77 +/- .58 (SE) ng/mL], baselin e T (.92 +/- .30 ng/mL), T peak number (6.1 +/- 1.2 per 12 h), T peak amplitude (2.77 +/- 1.70 ng/mL), or T peak length (79 +/- 24 min) were not significant (P > .05). The number of LH peaks was greater in the Continuous than Intermittent group (11.7 +/- .6 vs 6.8 +/- 1.4 per 12 h, P < .05), but there were no treatment differences in overall mean L H (4.56 +/- 2.09 ng/mL), baseline LH (4.10 +/- 2.11 ng/mL), LH peak am plitude (2.80 +/- .92 ng/mL), or LH peak length (15.9 +/- 3.1 min). Th ere were no differences in T or LH concentrations between the photo- a nd scotophases in the continuous group, and pulses of both were seen i n both phases in both lighting treatments. It was concluded that minor differences in patterns of LH secretion may occur between Continuous and Intermittent stimulatory lighting treatments in sexually mature ma le turkeys.