Dorsal hippocampal lesions in adult female rats leads to alteration in the estrus cycle with preponderance of estrus phase. The activity of the animals after the lesion increases, but it remains coupled with post lesion estrus cycle.

A study was conducted with 360 gilts and sows from four herds to determine whether fertility was affected when the final of multiple inseminations was performed in late estrus or metestrus (late insemination). Sows and gilts were inseminated at 24-h intervals immediately after the detection of estrus. After receiving a first insemination, females were paired according to parity and estrus statu...

Light-dark (LD) cyclicity contributes to a number of reproductive events in the rat, including estrus cyclicity, and the timing of parturition and postpartum estrus. Constant light (LL) disrupts the female's cyclicity, and fertility is typically diminished. To ascertain whether constant light similarly diminishes the fertility of postpartum females, LL and LD animals were compared over three su...

The objectives of this study were to evaluate estrus response and pregnancy rates resulting from timed artificial insemination (AI) following estrus synchronization using CIDR in postpartum beef cattle. A total of 100 cows were randomly divided into three groups. Groups 1, 2 and 3 were artificially inseminated at 48-50 h (n=30), 53-55 h (n=30) and 58-60 h (n=40) after CIDR removal, respectively...

Heat stress has two major consequences for the physiology of the cow that reduce its probability of becoming pregnant. First, changes in cow behavior (for example, reduced walking time; López-Gatius et al., 2005) and reduced circulating concentrations of estradiol-17β (Gilad et al., 1993) caused by heat stress reduce ability to detect estrus. On one dairy in Florida, only about 18-24% of estrus...

The beef cattle industry has seen rapid gains in economically desirable traits largely due to the selection and expanded use of genetically proven, superior sires made available through artificial insemination (AI). Recent surveys indicate, however less than 5% of the beef cows in the United States are bred by AI, and only half of the cattle producers who practice AI use any form of estrus sync...

Two experiments were conducted to evaluate an accelerometer system (Heatime; SCR Engineers Ltd., Netanya, Israel) to manage reproduction in lactating dairy cows. In experiment 1, lactating Holstein cows (n=112) were fitted with an accelerometer system and were treated with GnRH followed 7d later by PGF(2α) to synchronize estrus. A total of 89 cows that had a follicle >10mm in diameter and a fun...

We previously reported that ovulation rate, but not pregnancy rate or litter size at d 30 after mating, was enhanced by treatment with P.G. 600 (400 IU of PMSG and 200 IU of hCG, Intervet America, Inc., Millsboro, DE) in gilts fed the orally active progestin, altrenogest (Matrix, Intervet America, Inc.) to synchronize estrus. We hypothesized that in addition to increasing ovulation rate, P.G. 6...

Background: Recent studies have been conducted with the aim of improving fertility rates in FTAI programs beef females. The observation estrus expression constitutes an important indicator zebu Therefore, this work has as objective to evaluate impact on follicular, luteal and morphofunctional characteristics Nelore females synchronized for FTAI.Materials, Methods & Results: Sixty five lacta...

The intensity and duration of sexual behavior in Bos indicus was assessed through the continuous observation of sexual receptivity. Two groups of cows were formed: only synchronized (n = 50) and other group further superovulated (n = 20). An intravaginal implant that released progesterone over 9 d was used. After removing the implant, 25 mg of PGF2α was administered. In the superovulated group,...