Gonadotropin and gonado-bormone concetrations in the pygmy goat during transition from anestrus to breeding activity

Abstract

Blond samples obtained from two mature and two prepubertal female pygmy goats during anestrus up to four days after
first overt estrus were assayed for· gonadotropins and gonado-hormones by radioimmunoassay (RIA) techniques. The
prepubertal goats were aged 211 and 214 days respectively. All animals showed behavioral and endocrine changes that
were characteristic of t he estab lishment of normal estr us cycles between the 18th and 30th of November. The two
prepubertal does showed first overt estrus at the age of248 and 251 days, respectively. From progesterone concentration
profiles, all animals were observed to have had a presumed ovulation without overt estrus at an average of 19.2 :!: 0.5 days
before the first behavioral estrus. LH and FSH levels fluctuated randomly throughout anestrus; a two-to three fold
increl\Se in their mean values was appa•·ent 5 days before the pre-ovu latory surge prior to the first presumed ovulation.
The pattern of their secretion during the intenal from first Jlrcsumed ovulation to tlrst behavioral estrus was similar to
that observed during anestrus; both were elevated on the day of first behavioral estrus. Progesterone levels were low
during anestrus; their first elevation (from 0.5.:!: 0.08 to 2.3 + 0.4 ng/ml) occurred 2 days before the first presumed ovulation
(day-23). Du ring the interval between the first presumed ovulation and first overt estrus, progesterone concentrations and
pattern of secretion were characteristic of that observed during the normal cycle. Estradiol concentrations were varied
during anestrus and the interval from first presumed ovulation to first overt estrus. Levels of estradiol were observed to be
elevated a day before the LH/FSH preovulatory surges ofthc first pre. umcd ovulation and the first overt estrus, respectively.