Research has indicated that luteinizing hormone (LH) pulses play a vital role in corpus luteum (CL) formation and subsequent progesterone concentrations. Therefore, our objectives were to determine: 1) when LH pulses begin following onset of estrus, 2) the effect an injection of gonadotropin releasing hormone (GnRH) would have on initiation of LH pulses, and 3) the effect LH pulse initiation ha...

Ovulation rate was measured by laparoscopy at two consecutive cycles on 366 ewes 2 yr old and over and 85 yearling ewes of five lines of Targhees from the base base population; 53 yearling linecross ewes were also included. The lines were two unselected controls (HCl and DC), two selected for 21 yr for increased 120-d weight (HW and DH) and one selected for 19 yr for multiple births (T). Ewes w...

In normal production practices, sows and gilts are inseminated at least twice during estrus because the timing of ovulation is variable relative to the onset of estrus. The objective of this study was to determine if a normal fertilization rate could be achieved with a single insemination of low sperm number given at a precise interval relative to ovulation. Gilts (n=59) were randomly assigned ...

Progesterone, estrogen, LH, FSH and PRL variations in plasma were measured in 7 goats by RIA. Mean progesterone level was 0.0-0.8 ng/ml in estrus and 1-4 ng/ml in diestrus. Estrogen levels ranged from 10 to 20 pg/ml in diestrus; around estrus, a peak of 26.9 +/- 3.18 pg/ml was observed. LH values were 0.5-3.0 ng/ml with a preovulatory peak (40.7 +/- 10.12 ng/ml) 8 to 24 h after the onset of est...

In rodents, the display of sexual behavior during proestrus-estrus transition depends on the effect of estradiol and progesterone. Progesterone exerts its effects through intracellular receptor (PR) of which two isoforms (PR-A and PR-B) are found, with different regulation and function. In this study the effects of mating on the expression pattern of PR isoforms in the hypothalamus were investi...

this study was carried out at sakha animal production research station, during the period from oct., 2009 to sept., 2010. forty rahmani ewes were divided into three treatment groups: the 1st, 2nd and 3rd treatment groups were intramuscularly injected (day 0) with 1 ml gnrh analogue followed by an intramuscular injection with 0.7 ml pgf2α5 (g1), 6 (g2) or 7 (g3) days later. a second dose of 1 ml...

An algorithm that mathematically describes annual estrous activity in ewes is given. The function fitted as the ordinate is similar to a normal distribution function related to date as the abscissa. The data used were collected from literature on different breeds and from different locations of the world; all studies had been specifically conducted to study estrous activity in ewes in these loc...

To investigate the IgG content and its variations in uterine fluid (UF) during the estrous cycle of the cow and to compare them with those of the blood serum (S), six pairs of serum and UF samples for each phase of the cycle selected out of 240 bovine genital tracts and blood samples were collected from Urmia abattoir. The UF samples were collected by gentle scraping of the endometrium using a ...

Progesterone is a potent drug for synchronization of the estrus and ovulation cycles in bovine. At present, the estrus cycle of bovine is controlled by the insertion of progesterone-embedded silicone bands. The disadvantage of nondegradable polymer inserts is to require for disposal of these bands after their use. The study currently focuses on preparation of biodegradable progesterone-incorpor...

A study was conducted over a 2-mo period to compare estrus detection results obtained using an androgenized teaser mare with those obtained with a stallion, using the same group of 10 normally cyclic mares. The teaser mare was androgenized by administration of boldenone undecylenate (500 mg i.m. every 1 to 2 wk), and allowed to run loose with the mare group. Estrus was determined by observation...