Periódicos Brasileiros em Medicina Veterinária e Zootecnia

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Variation of sexual behavior of photo-stimulated bucks during the transition from winter to spring in the semi-arid climate of Mexico

Sifuentes, LuisPalomo Peiró, María JesúsUlloa-Arvizu, RaúlDuarte, GerardoSifuentes-Lamónt, PabloFernández, Ilda Graciela

Sheep and goat production takes place under unsuitable climate conditions, where animals are more susceptible to high temperatures. The objectives of this study were to determine, i) whether sexual behavior of photo-stimulated bucks varies through 24 h/day in March and April and, ii) whether the environmental temperature and the relative humidity affect their expression. Six bucks were submitted to artificial long days (16 h light and 8 h darkness per day/2.5 months). Bucks were exposed to ovariectomized females once a week during the non-breeding period and sexual behavior was recorded for 15 min at 2 h intervals along 24 h/day. The environmental temperature, relative humidity, temperature-humidity index (THI), and body temperature were recorded in each behavior test. Plasma testosterone, sexual behavior, environmental temperature, relative humidity, and body temperature were analyzed using Generalized Estimation Equations. Plasma testosterone showed a significant difference over the experimental period (P < 0.001). The highest frequency of nudging and anogenital sniffing was at 08:00 h (P < 0.001); flehmen and penis unsheathed were variable (P < 0.001). The highest environmental temperature and the lowest relative humidity were registered from 14:00 to 18:00 h (P < 0.001). The highest body temperature was at 18:00 h and the lowest was at 06:00 h (P < 0.001). The highest THI >77 was recorded at 16:00 h. In conclusion, photo-stimulated bucks showed a variation of sexual behavior through 24 h/day exposed to ovariectomized females, and these sexual activities were affected by the high environmental temperature and the low relative humidity throughout the study.(AU)

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