183 PREGNANCY RATE FOLLOWING TRANSFER OF IN VITRO- AND IN VIVO-PRODUCED BOVINE EMBRYOS TO LH-TREATED RECIPIENTS
J. Small A , M. Colazo B , D. Ambrose C , R. Mapletoft C , J. Reeb D and J. Kastelic EA Agriculture and Agri-Food Canada, Research Centre, Brandon, Manitoba, Canada. email: jsmall@agr.gc.ca;
B WCVM, University of Saskatchewan, Saskatoon, Saskatchewan, Canada;
C Alberta Agriculture Food and Rural Development, Edmonton, Alberta, Canada;
D Canadian Central Genetics, Selkirk, Manitoba, Canada;
E Agriculture and Agri-Food Canada, Research Centre, Lethbridge, Alberta, Canada.
Reproduction, Fertility and Development 16(2) 213-213 https://doi.org/10.1071/RDv16n1Ab183
Submitted: 1 August 2003 Accepted: 1 October 2003 Published: 2 January 2004
Abstract
The objective was to evaluate the effect of pLH treatment on pregnancy rates in recipients receiving in vivo- or in vitro-produced bovine embryos. Heifers (n = 37) and lactating (n = 28) and non-lactating (n = 150) beef cows were treated at random stages of the cycle with 100 μg GnRH i.m. (Cystorelin, Merial Canada Inc., Victoriaville, Quebec, Canada) on Day −9, 500 μg cloprostenol i.m. (PGF; Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada) on Day —2 and GnRH on Day 0 (66 h post-PGF; without estrus detection). Cattle were placed at random, by class, into three groups: no further treatment (Control; n = 71), or 12.5 mg pLH (Lutropin-V, Bioniche Animal Health, Belleville, Ontario, Canada) on Day 5 (n = 72) or on Day 7 (n = 72) after the second GnRH. On Day 7, cattle with a CL > 10 mm in diameter (determined ultrasonically) received in vivo-produced, fresh (Simmental) or frozen (Holstein), or in vitro-produced frozen (Holstein) embryos (embryo type balanced among groups). Embryos were cryopreserved in 10% ethylene glycol; in vivo-produced frozen embryos were thawed 5 to 10 s in air, 15 s in a water-bath at 30°C and then “direct-transferred” nonsurgically. In vitro-produced frozen embryos (donated by IND Lifetech Inc., Delta, British Columbia, Canada) were thawed in a water-bath at 27°C for 10 s and placed in ViGro Holding Plus medium (AB Technology, Pullman, WA, USA) at room temperature, evaluated and then transferred nonsurgically. Pregnancy was determined by ultrasonography on Day 35. Data were analyzed with CATMOD, chi-square and GLM procedures (SAS Institute, Cary, NC, USA.). Twenty cattle (9.3%) did not receive embryos; five heifers had cervical problems, and five heifers and 10 cows did not have a CL >10 mm. Overall, 7.1% of the recipients had two CL on the day of embryo transfer. There was no effect (P > 0.05) of treatment, embryo type (or interaction) or class of recipient on pregnancy rate (overall, 44.1%, 86/195; Table 1). Similarly, mean (±SD) CL diameter and luteal area did not differ (P > 0.05) among groups or between pregnant and open recipients (overall, 22.0 ± 3.4 mm and 352.0 ± 108.7 mm, respectively). However, recipients with a CL diameter ≥18 mm tended (P < 0.1) to have a higher pregnancy rate (45.8 vs 25.0%). In a subset of 40 recipients examined ultrasonically on Day 12, 50% of those treated on Day 5 and 70% of those treated with pLH on Day 7 had two CL. In summary, overall pregnancy rate in GnRH-synchronized recipients receiving in vitro- or in vivo-produced embryos by nonsurgical transfer was 44.1%. Embryo survival to Day 35 was not affected by type of embryo or treatment with pLH 5 or 7 days after ovulation.
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