12 research outputs found
Administration of human chorionic gonadotropin at embryo transfer induced ovulation of a first-wave dominant follicle and increased progesterone and transfer pregnancy rates
Beef Cattle Research, 2011 is known as Cattlemenâs Day, 2011Embryo transfer (ET) has become more widespread in recent years as a way to improve
cattle genetics. According to the annual statistical survey of the American Embryo
Transfer Association, more than 200,000 fresh and frozen bovine embryos were
transferred in 2008. But despite advancements in reproductive technologies that have
occurred since ET was commercialized in the 1970s, industrywide pregnancy rates are
only 62.4 and 56.9% for fresh and frozen-thawed ET, respectively. Using ET helps
avoid problems from failed fertilization; however, fertilization failure has been characterized
as a relatively unimportant factor of pregnancy loss. Approximately 10% of pregnancy
failures resulted from fertilization failure and another 10% from failed embryo
development. Approximately 20 to 25% of the pregnancy loss in an ET program could
be characterized as early embryonic loss
Efficacy of electronic identification in beef cattle
To evaluate the potential of using electronic
implants (transponders) for maintaining identity
from birth to slaughter, calves born and
implanted in Montana were followed through
the feedlot phase to their ultimate slaughter at
commercial packing plants. At spring branding,
138 calves were implanted with electronic
identification transponders positioned
underneath the scutiform cartilage at the base of
the ear. Four steers died prior to weaning.
After weaning, 109 steers were transported to a
commercial feedlot i n Kansas (group 1) and the
remaining 25 steers (group 2) were maintained
at the Montana ranch for 1 year and then placed
in a commercial feedlot in Colorado. Following
the two feeding periods, steers were
slaughtered at commercial packing plants in
Colorado or Kansas under Food Safety
Inspection Service authority. From implanting
to weaning (156 days), retention was 100%, and
98.5% of the implants remained operable. Of
the 106 steers that survived in the first group,
implant retention was 98.1%, and all implants
were recovered at slaughter. Of the 25 steers in
the second group, identity was maintained on 20
steers up to slaughter, 661 days postbranding.
This study illustrated that electronic implants
will maintain identity on a very high percentage
of cattle from birth to slaughter and that the
implants can be recovered at the time of
slaughter
Pregnancy rates in MGA-prostaglandin synchronized heifers bred at estrus or inseminated at fixed times
The objective of this project was to study
the effects on pregnancy rates of inseminating
estrus-synchronize d heifers either at observed
estrus or at a fixed time. In April, 1994, 574
yearling crossbred heifers, located on six
Kansas ranches, were inseminated to achieve
this objective. Her d size ranged from 38 to 293
head. The heifers were synchronized with the
MGA-prostaglandin (PGF) system. Heifers
were either inseminated 12 hr after the onset of
estrus or, if not showing estrus, 72 hr after PGF.
Pregnancy rates of 491 heifers bred on estrus
averaged 56.6% (39.2 to 80.4%). Pregnancy
rates for the 83 fixed-time-inseminated heifers
average d 39.8% (15.6 to 56.5%) . Heifers that
responded to the MGA-PGF synchronization
system with a standing heat had higher
pregnancy rates than those that were
inseminate d at a fixed time. However, fixed-time
inseminations used in conjunction with
inseminations made at estrus increased the total
number of heifers bred to proven AI sires
Pla figura del Sr. Pasqual Maragall i del Rector Jaume PagĂšs rient amb una petita comitiva durant la mostra de la maqueta de la residĂšncia d'estudiants de Ciutat Vella
This study evaluated the effect of implanting potential replacement heifers (n=548) with Component E-CÂź (10 mg of estradiol and 100 mg of progesterone) between 45 and 120 days of age or at weaning (200 days of age) on future reproductive performance. Trials were conducted at five ranches in Kansas and one in Nebraska. At each location, heifers were allotted to three treatments: no implant (Control), one implant at 45 to 120 days of age (Early- IMP), or one implant at 2 00 days of age (Wean- IMP). No differences were detected among treatments for first service conception rate (55%), overall pregnancy rate (85%), or calving rate (80%). In addition, no differences were observed among treatments for pelvic area, reproductive tract score, or calving difficulty or for birth or weaning weights of their calves. We conclude that implanting replacement heifers with Component E-C early in life or at weaning had no effect on their subsequent reproductive performance
Effect of breed and corpus luteum on pregnancy rate of bovine embryo recipients
The objective of this study was to evaluate pregnancy rates of recipients of different breed groups (Nellore and crossbreed), as well as the effects of size and type of the corpus luteum (CL) on plasmatic concentrations of progesterone and pregnancy rates of embryo recipients. A total of 152 heifers were synchronized with progesterone implants and on the day of embryo transfer, previously obtained by superovulation and frozen in ethylene glycol, the diameter and type of the corpus luteum (cavitary and compact) was measured and blood was collected for progesterone measurement. The pregnancy rate was 44.1%, with a diameter of corpus luteum higher in recipients that became pregnant (2.03±0.41) compared with non-pregnant ones (1.86±0.34 cm). Plasmatic concentrations of progesterone did not differ between pregnant (1.50±1.05) and non-pregnant (1.31±0.91 ng/mL) animals. The type of corpus luteum did not influence the pregnancy rates. Only Angus and crossbred Marchigiana differ among themselves in pregnancy rates (33.3 and 59.2%, respectively). The pregnancy probability was affected only by CL diameter, but not by P4 plasmatic concentration. Selection of the corpus luteum size at the time of embryo transfer is an important factor to increase pregnancy rates in recipients, and compact and cavitary corpora lutea do not influence the pregnancy rates of bovine embryo recipients. Nellore recipients have pregnancy rates that are satisfactory and comparable to crossbred (Bos taurus à Bos indicus) recipients