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ARS Home » Pacific West Area » Dubois, Idaho » Range Sheep Production Efficiency Research » Research » Publications at this Location » Publication #148397

Title: EFFECT OF STRESS ON CORTISOL AND TESTOSTERONE IN LOW AND HIGH LIBIDO RAMS

Author
item Stellflug, John
item ROSELLI, CHARLES - OREGON HEALTH SU
item STORMSHAK, FRED - OREGON STATE UNIV

Submitted to: Society for the Study of Reproduction Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: 2/4/2003
Publication Date: 7/1/2003
Citation: Stellflug, J.N., Roselli, C.E., Stormshak, F. Effect of stress on cortisol and testosterone in low and high libido rams. Biology of Reproduction. 2003. v. 68(Suppl 1) Abstract p. 379-380.

Interpretive Summary:

Technical Abstract: Our objective was to determine effect of restraint stress on cortisol (C) and testosterone (T) in low versus high libido rams. Restraint stress or minimal stress was imposed on low (n = 14) and high libido (n = 16) rams in a 2 x 2 factorial. Rams were randomly assigned to restraint or control within ram class. Rams were habituated to wearing halters and being tethered in separate pens permitting visual, vocal, and olfactory contact with adjacent rams for 7d before treatment. After 1d of habituation, rams were fitted with jugular catheters and checked 2x daily for patency. For restraint stress, rams were laid on their side with legs tied for 1 h. For minimal stress, rams were haltered but not tied down. On treatment day, blood was collected at 30-min intervals for 3 h followed by 15-min for 1 h before restraint, during 1 h restraint, and for 1h after rams were untied. Then blood was collected at 30-min intervals for an additional 2 h. Similarly, blood was collected from controls. All rams remained in their home pens with controls isolated from stressed rams. The C and T were measured with RIA. Mixed model analyses with repeated measures were used on transformed data. Average prestress data was used as a covariate. For C, stress treatment x ram class interaction (P < 0.03) related to stress increasing (P < 0.001) C (LSM " estimated SE) from 4.9 " 0.7 in low libido controls to 13.5 " 1.8 in stressed low rams whereas C increased from a lower value in high libido controls (3.2 " 0.5 ng/mL) to a greater value in stressed high libido rams (16.3 " 1.7 ng/mL). For T, stress treatment x time interaction (P < 0.002) related to T remaining stable at 18 to 25 ng/mL in controls over time and decreasing (P < 0.05) from similar levels in controls to 15.8 " 2.9 within 75 min and to 8.2 " 1.1 ng/mL at 4 h after onset of restraint. We conclude that restraint stress increased C and decreased T similarly in both low and high libido rams thus not differentiating by ram class.