OBJECTIVE In this study, we examined changes in serum leptin levels during the estrus cycle and the role of estrogen in these changes. METHODS We measured serum leptin levels during normal estrus cycles in intact rats and estradiol-17beta (E2)-induced artificial estrus cycles in ovariectomized rats. RESULTS Serum leptin levels increased 1.6-fold from 4.2 +/- 0.2 ng/ml during diestrus stage ...

The aim of this study was to evaluate the reproductive efficiency of short and long term treatment with progestagens in addition to pregnant mare serum gonadotropin (PMSG) in Arabian ewes during the non-breeding season. A total of 56 ewes were divided into three groups: in group I vaginal sponges (60 mg medroxy progesterone acetate; MAP) were applied and removed after 6 days; in group II, vagin...

the aims of this study were (a) to establish the occurrence, duration and intensity of behavioral estrus symptoms, and (b) to determine the relationship between behavioral estrus symptoms with the total estrogen profiles in cycling murrah buffaloes (n=10) subjected to doublesynch protocol (0 pgf2α, 2 gnrh, 9 pgf2α and 11 gnrh). after both gnrh injections, estrus and its behavioral signs were de...

Cows that exhibit estrus within 24 h of fixed-time AI have elevated concentrations of estradiol and greater pregnancy rates compared with cows not in estrus. Our objective was to determine whether estradiol, estrus, or both had an effect on uterine pH during a fixed-time AI protocol. Beef cows were treated with the CO-Synch protocol (100 mircog of GnRH on d -9; 25 mg of PGF(2alpha) on d -2; and...

On February 4, 14 of 28 seasonally anestrous mares were fed .044 mg per kilogram of body weight of an oral progestin, allyl trenbolone (17a-allyl-estratriene 4-9-11, 17/3-ol-3-one) for 12 days. There was no difference (P>.05) between groups for the number of mares exhibiting estrus after treatment or follicular activity during or after treatment. After March 6, 18 mares that had not yet ovulate...

Spring-calving Angus cows (n = 30) were used to evaluate changes in ruminal temperature (RuT) related to parturition and estrus. Cows were synchronized and artificially inseminated with semen from a single sire. Temperature boluses were placed in the rumen at 7.0 ± 0.2 mo of gestation. Boluses were programmed to transmit RuT every 15 min. Cows (BW = 623 ± 44 kg, BCS = 4.9 ± 0.4) calved during 3...

Traditional methods of estrus synchronization developed over the past 60 yr have involved controlling bovine estrous cycle length by administering a progestin and/or regressing the corpus luteum with luteolytic drugs. The synchrony of estrus and timing of ovulation following traditional estrus synchronization treatments has been too variable to allow the transfer of a fresh or frozen/thawed emb...

The purpose of this study was to determine whether administration of altrenogest (Regumate; Roussel-Uclaf, París, France) to primiparous sows would improve estrus synchronization rate and reproductive efficiency of the herd, measured in terms of the weaning-to-estrus interval (WEI), the weaning-to-first-fertile-estrus-interval (WFEI), rate of sows repeating estrus, and conception rate at first ...

The influence of litter separation (LS) that included a change in housing environment and social status of sows, boar exposure (BE), and parity on estrous expression by sows during and after lactation was examined in two experiments utilizing 140 crossbred sows. In Exp. 1 (Yorkshire X Duroc sows), limiting duration of LS to 6 or 3 h/d during the last 8 d of lactation in two trials, while mainta...

The objectives were to determine the effects of insemination with sexed semen at spontaneous and induced estrus, fixed-time insemination at synchronized estrus, the deposition site, estrous intensity, housing, age, body weight, and bull on the pregnancy rate in Holstein heifers, and to compare the quality traits of sexed sperm with those of unsexed semen. The study was conducted on 3206 heifers...