10 research outputs found

    Early postpartum luteal function after treatment with progestin and(or) gonadotropin-releasing hormone in dairy cattle

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    Progestin (Norgestomet®) and(or) repeated low-dose infusions of GnRH (Cystorelin@) influenced the lifespan of the first corpus luteum after an induced ovulation. Holstein cows (n=32) were assigned at calving to four groups. Cows were treated with blank ear implants (days 2 to 9 after calving) and saline infusion (48 hr on days 10 arid II), progestin ear implants and saline infusion, blank implants and GnRH infusion, or progestin implants and GnRH infusion prior to a GnRH-induced ovulation (day 12). Four primiparous and four multiparous cows were assigned to each treatment. Fewer cows treated with progestin/GnRH ovulated in response to the GnRH challenge. However, short cycles (<17 days in duration) were prevented in all cows (n= 16) treated with progestin. In addition, all multiparous cows treated with blank implants and GnRH infusion had normal cycles. Results of this study suggested that progestin and GnRH may have altered follicular development, thereby preventing the short-lived corpus luteum and inducing a normal estrous cycle as cows overcame anestrus early postpartum

    Pregnancy rates of dairy cows at first service: influence of gonadotropin-releasing hormone and timing of AI relative to estrus

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    The 1989 Annual KSU Dairy Day is known as Dairy Day, 1989We demonstrated that gonadotropin-releasing hormone (GnRH or Cystorelin®) failed to improve pregnancy rates at the first service. When GnRH injection and insemination are both carried out either in early or late estrus or if cows are bred in early estrus and given a GnRH injection later in estrus, pregnancy rates are reduced by 9 to 13 percentage points compared to breeding according to the am-pm rule without GnRH treatment (control). Pregnancy rates of cows injected with GnRH early in estrus and bred in late estrus were similar to controls injected with saline and inseminated late in estrus (46 vs 43%). Altering the time of breeding and the time of GnRH injection to either early or late estrus did not improve pregnancy rates. We continue to recommend using GnRH only for repeat breeders, because GnRH consistently improves pregnancy rates at 3rd or 4th service, but not at first services

    Influence of prebreeding progesterone plus prostaglandin F2-α on estrus and fertility in lactating dairy cows

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    Progesterone administered before breeding may increase estrous expression and subsequent fertility in lactating dairy cows. Holstein cows (n=302) were assigned randomly at calving to three groups. Cows received no treatment (controls), one injection of prostaglandin F 2-α (PGF), or progesterone plus one injection of PGF (PRID + PGF). The average interval to estrus was 5 days shorter in PRID + PGF cows compared to cows given only PGF. In addition, more cows were observed in estrus 2 to 5 days after treatment in the PRID + PGF group compared to the PGF group. Average days from calving to conception were reduced in PRID + PGF cows by 15 to 20 days compared to control and PGF cows. We concluded that prebeeding progesterone in combination with PGF appears to enhance fertility.; Dairy Day, 1987, Kansas State University, Manhattan, KS, 1987

    Concentrations of progesterone and conception rates in Holstein heifers after hCG administration during the first 3 weeks after estrus

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    We conducted two experiments to determine the effects of administering human chorionic gonadotropin (hCG) on day 4 or on days 15, 16, and 17 after estrus on conception rates and progesterone secretion by the corpus luteum in Holstein heifers. In the first experiment, 60 heifers received hCG or saline on day 4 after estrus and AI. Conception rates were similar between groups. Concentrations of progesterone were increased in treated pregnant and nonpregnant heifers 7 and 14 days after treatment compared with pregnant and nonpregnant controls. In the second experiment, 62 heifers received hCG or saline on days 15, 16, and 17 after estrus and AI. Conception rates again were similar between groups. Concentrations of progesterone were higher in treated pregnant heifers on days 16, 17, and 21 after estrus and in treated nonpregnant heifers on days 17 and 21 compared with pregnant and nonpregnant controls. We conclude that stimulation of the newly formed or mature corpus luteum by hCG increased production of progesterone without affecting conception rates

    Induction of estrus in thyroidectomized-ovariectomized, nonlactating, holstein cows

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    Low thyroid activity (hypothyroidism) has been reported to decrease sexual behavior associated with reproduction in several species. Using estradiol benzoate (EB) and progesterone (P ), we attempted to induce 4 estrus in hypothyroid cows. Thyroid glands (thyroidectomy) and ovaries (ovariectomy) were removed surgically from nonlactating and nonpregnant Holstein cows that were culled from the Kansas State University dairy herd. Eight cows were thyroidectomized and ovariectomized (THYOVEX) and another four cows were ovariectomized only (OVEX). Starting 9 hr after injection of EB, cows were continuously observed for estrus for 36 hr. Frequencies of mounting activity and standing behavior were recorded for each cow. The percentage showing standing estrus was greater in cows that had no thyroid glands or ovaries than in cows without ovaries (78 vs 31%). Manifestation of estrus was identical in cows treated with EB or EB+P (62%). Interval from 4 EB injection to onset of standing estrus, frequency of mounting activity, and duration of standing estrus were similar among treatment groups and unaffected by the type of hormonal treatment. Thyroidectomized cows can exhibit estrous behavior, which is similar to that in ovariectomized cows treated with EB or P +EB

    Influence of prebreeding progesterone plus prostaglandin F2-alpha on estrus and fertility in lactating dairy cows

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    Progesterone administered before breeding may increase estrous expression and subsequent fertility in lactating dairy cows. Holstein cows (n=302) were assigned randomly at calving to three groups. Cows received no treatment (controls), one injection of prostaglandin F 2-alpha (PGF), or progesterone plus one injection of PGF (PRID + PGF). The average interval to estrus was 5 days shorter in PRID + PGF cows compared to cows given only PGF. In addition, more cows were observed in estrus 2 to 5 days after treatment in the PRID + PGF group compared to the PGF group. Average days from calving to conception were reduced in PRID + PGF cows by 15 to 20 days compared to control and PGF cows. We concluded that prebeeding progesterone in combination with PGF appears to enhance fertility

    Determinants of Circadian Blood Pressure Variation: A Community-Based Study in Ohasama.

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    DNA and Double-Stranded Oligonucleotides

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    A highly virulent variant of HIV-1 circulating in the Netherlands.

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    We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log &lt;sub&gt;10&lt;/sub&gt; increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence
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