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 Cattlemen’s 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 Pagès rient amb una petita comitiva durant la mostra de la maqueta de la residència d'estudiants de Ciutat Vella

This study evaluated the effect of implanting potential replacement heifers (n=548) with Component E-C® (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 × Bos indicus) recipients