Alteration of Ingestive Behavior and Plasma Metabolites by Estrogen in Ovariectomized Goats.

Abstract

Abstract. Ovariectomized goats were treated with subcutaneous implants containing ovarian steroid hormones and their effects on ingestive behavior and plasma metabolite concentrations were examined along with those on reproductive function. Sequential administrations of progesterone (P) and estradiol (E) reproduced steroidal milieu during the luteal through the follicular phases. Around 35 hours after the commencement of the E administration, estrous behavior appeared, and almost simultaneously the luteinizing hormone surge occurred. During the estrous period, amount of food intake and duration of rumination markedly decreased, whereas plasma concentrations of glucose and free fatty acid increased. These changes lasted until the E-implant was removed. The E administration without P pretreatment induced similar changes in reproductive, ingestive and metabolic parameters, although the occurrences of these were all advanced. In contrast, the administration of P alone had no such effect on any parameter. These results demonstrate that estrous behavior is accompanied by changes in feeding behavior and metabolism, and suggest that E is playing essential roles to prepare female for mating by coordinating diverse physiological functions in the goat. Key words: Estrogen, Ingestive behavior, Plasma glucose, Plasma free fatty acid, Goats.(J. Reprod. Dev. 44: [141][142][143][144][145][146][147][148] 1998) strous behavior is an integral part of the female reproductive cycle and its expression is restrictas well. The roles of steroid hormones have been well documented in nonruminant species such as rats [6][7][8], guinea pig [9], rhesus monkey [10] and human [11]. It has been thought that the decrease in food intake at estrus is due to an action of estrogen, because ovariectomy results in hyperphagia and this effect can be reversed by treatment with estrogen [7,8]. In ruminants, however, despite that there are several previous reports which demonstrate effects of estrogen on food intake in castrated males [12] and ovary intact females [12][13][14], precise roles of ovarian steroids in the control of ingestive behavior have not been systematically

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

“…The reproductive cycles of female goats were monitored by behavioral observation to avoid using females in estrus. The criteria for determining estrus by observing behavior were as described (Aoyama et al . 1998a).…”

“…Three capsules each containing 0.1 g of Es made of silicon tubing (3.55 mm i.d., 4.65 mm o.d., 40 mm length: AS ONE, Osaka, Japan) were implanted into one animal. Published reports indicate that this method restores the blood concentration of Es to that of intact females (Aoyama et al . 1998a,b).…”

Effects of Bilateral Ovariectomy (OVX) on Thermoregulation and Blood Constituents in Adult Nubian Goats (Capra hircus)

“…Pang et al [37] found that oestradiol and progesterone levels deceased on day 5 after ovariectomy in Huanghuai goats. In addition, Aoyama et al [38] indicated that the levels of oestrogen and progesterone concentrations declined to low values after 3 weeks in ovariectomized goats. In humans, the core body temperature corresponds with the level of female sex hormones, and it decreases with low level and increases with high level of female sex hormones [39].…”