THE EFFECT OF BREEDING FACILITY AND SEXUAL STIMULATION ON PLASMA-CORTISOL IN BOARS

Nine boars were used to evaluate effects of breeding facility design a nd sexual activity on plasma cortisol concentrations. In one breeding facility (conventional), boars were housed individually in small pens, and female pigs were mated in those boar pens. In another breeding fa cility (Detection-Mating Area [DMA] system), boars were housed individ ually in stalls, and female pigs were mated in a specific mating pen a djacent to the front of stalls where boars were housed. After 51 d of housing treatment, a catheter was surgically implanted in the cephalic vein for collection of blood samples. Daytime profiles (hourly collec tions from 0900 to 1700) of cortisol did not differ among boars in the two treatment groups. Cortisol was greater (P < .01) in the morning t han in the afternoon. Administration of ACTH increased (P < .001) plas ma cortisol in boars, but breeding facility did not affect the ACTH-in duced changes in cortisol concentrations. There was a treatment x time interaction (P < .02) for cortisol after sexual stimulation, and the magnitude and duration of increase in cortisol were greater (P < .05) in the DMA treatment group. Cortisol was greater (P < .001) after than before mating for both treatment groups. An acute increase in plasma cortisol concentration in boars seems to be a normal biological respon se to sexual activity. However, magnitude and duration of the increase in cortisol may be influenced by breeding facility design and mating procedure. There is no evidence, based on physiological data, that hou sing boars in stalls in the DMA system has any adverse effects on thei r welfare.