Abstract
One hundred ninety ejaculates were collected from 16 healthy Arab stallions (5-18 years; 12 normal and four slow breeders) over 12 months, and sexual behavior parameters were recorded. Serum samples were collected from stallions for determination of testosterone, estradiol-17 beta, cortisol, and glucose. The results revealed that the time to first mount, latency to erection, latency to mount, and number of mounts per ejaculate were significantly (P < .001) shorter in normal breeders (61.12 +/- 5.18, 49.45 +/- 3.78, 82.54 +/- 639, and 1.32 0.04, respectively; n = 12) than in slow breeder stallions (259.82 +/- 42.66, 228.26 +/- 50.48, 371.95 +/- 36.27, and 2.63 +/- 0.35, respectively; n = 4). Sexual behavior abnormalities constituted 10.42% of all trials. Season exerted a significant (P < .05) effect on all sexual behavior parameters except latency to ejaculation, which was the shortest during spring in the normal breeders. Sexual behavior abnormalities were significantly (P < .05; 37%) higher in all stallions during autumn. Both serum estradiol-17 beta and cortisol levels rose significantly (P < .05) after semen collection in all stallions. Serum estradiol-17 beta level was significantly (P < .05) increased during spring and summer in all stallions. Cortisol levels were significantly (P < .05) higher during autumn in both normal and slow breeder stallions (2,121.15 +/- 115.55 and 69.37 +/- 21.84 pg/mL, respectively). In conclusion, sexual behavior parameters in normal breeders were shorter in duration than that recorded in slow breeder stallions. Season affects sexual behavior parameters and serum estradiol-17 beta levels, with the highest values found during spring and summer. Estradiol-17 beta and cortisol were the two hormones responsible for sexual behavior in stallions. The best sexual behavior was accompanied by low levels of serum testosterone. (C) 2015 Elsevier Inc. All rights reserved.