Sex differences in stress responses to transportation in goats: Effects of gonadal hormones

The present study examined sex differences and the involvement of gonadal hormones in stress responses caused by road transportation in Shiba goats. In experiment 1, we investigated the stress responses of males and females to transportation. Plasma levels of cortisol (Cor) significantly increased during 1 h of transportation, and those in females were significantly higher than those in males. Plasma glucose (Glu) and free fatty acid (FFA) levels also increased similarly in both females and males by transportation, and there were no sex differences. Food intake following transportation decreased only in males compared with that in the basal session, in which the animals were not transported. Experiment 2 examined the involvement of gonadal hormones in stress responses to transportation using castrated males. Goats were given cholesterol (Cho), 5α-dihydrotestosterone (DHT) or 17β-estradiol (Es). The plasma Cor levels increased during transportation regardless of hormone treatment, and those in DHT treated goats were significantly lower than those in Cho or Es treated animals. Plasma Glu and FFA levels also increased during transportation, regardless of hormone treatment, and there were no differences between treatments. Food intake following transportation was significantly lower than that in the basal session only in goats given DHT. In conclusion, gender affects Cor secretion that is increased by transportation and the decrease of food intake following transportation in Shiba goats, and the major cause of these differences is androgen.