10 research outputs found
Early postpartum luteal function after treatment with progestin and(or) gonadotropin-releasing hormone in dairy cattle
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
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
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
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
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
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
A highly virulent variant of HIV-1 circulating in the Netherlands.
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 <sub>10</sub> 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