UTERO-OVARIAN INTERRELATIONSHIPS IN PREPUBERAL AND GONADOTROPHS TREATED GILTS

Abstract

Reproductive tracts from 66 prepuberal, 45 cycling and 59 gonadotrophin-treated prepuberal gilts were examined and measured to determine the effect of puberty and gonadotrophin treatment on utero-ovarian interrelationships. Occurrence of the first ovulation resulted in significant (P < 0.05) increases in uterine weight and length but not in uterine wall thickness. This change was observed after both the first spontaneous ovulation and ovulation induced by injecting 1000 IU or 2000 IU of pregnant mare’s serum (PMS) followed 48 hours later by an injection of 500 IU of human chorionic gonadotrophin. Increasing the dose of PMS from 1000 IU to 2000 IU had no effect on uterine growth. Within untreated puberal females, ovarian weight was positively (P < 0.01) correlated with uterine horn weight, length and wall thickness, whereas within prepuberal females only uterine wall thickness was correlated (P < 0.01) with ovarian weight. Seven (41%) of the 17 gilts induced to ovulate at 55 kg and slaughtered at 90 kg were cycling when slaughtered, while none of the control females were cycling. Effects of the gonadotrophin treatment on tract development in prepuberal gilts were not apparent after the first spontaneous ovulation.