Influence of ambient temperature on ovarian response and hormonal levels in gilts
1997
Annop Kunavongkrit | Wichai Tantasuparak | Wanpen Srianan (Chulalongkorn Univ., Bangkok (Thailand). Faculty of Veterinary Science. Dept. of Obstetrics Gynaecology and Reproduction)
Fourteen pubertal gilts were divided into two groups. Control group (1C-7C), were kept in a conventional environment while the treated group (1T-7T) were put into a control temperature chamber from three days before their expected oestrus until three days after the end of oestrus (35 deg C during the day and 20 deg C during the night). Laparoscopic examination was performed to examine the status of the ovarian response to the treatment. Blood samples were collected from all gilts via an indwelling silastic tube, which was inserted in the jugular vein, 3 times a day. Blood plasma was determined for cortisol and progesterone levels by radioimmunoassays. Six of the seven control gilts (85.7 percent) had normal ovulatory oestrus while one (14.3 percent) had an anovulatory oestrus. Four treated gilts 57.1 percent) had a normal ovulatory oestrus, while the other three (42.9 percent) were abnormal: showing delayed anovulatory oestrus, anoestrus and developed follicular cysts. The plasma progesterone levels confirmed in the clinical and morphological findings shown by laparoscopy. The plasma cortisol levels in ovarian disordered gilts during proestrus, were higher than those in normal oestrus gilts. It can be concluded that elevated ambient temperature may stress the gilts cause elevated plasma levels of cortisol and may be one of serveral factors inhibiting gonadotrophins and results in reproductive dysfunction which includes anoestrus, delayed anovulatory oestrus and cystic ovaries.
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