Document Detail

Embryo loss in cattle between Days 7 and 16 of pregnancy.
MedLine Citation:
PMID:  19880168     Owner:  NLM     Status:  MEDLINE    
Embryo loss between embryonic Days 7 and 16 (Day 0=day of IVF) in nonlactating cattle, Bos taurus, was analyzed using transfer of 2449 (in groups of 3 to 30) in vitro-produced (IVP) blastocysts. In 152 transfers, pregnancy losses attributable solely to recipient failings amounted to between 6% (beef heifers) and 16% (parous dairy cows), of which 3% were caused by uterine infections. Neither season, year, nor the age of the embryos on retrieval affected pregnancy rates. The latter observation indicated that the reason that a recipient failed to retain embryos was already present at the time of transfer. Notably, the proportion of embryos recovered decreased (P=0.03) as more embryos were transferred, particularly at later stages (Day 14, P<0.01). The average length of embryos decreased by approximately 5% for every additional embryo transferred (P<0.0001). These effects may be linked to embryonic migration. Embryo mortality inherent to the embryo during the second week of pregnancy was 24%. Additionally, 9% of Day 14 embryos were of inferior quality, as they did not contain an epiblast. Combining embryo and recipient causes but excluding infection effects, embryonic loss of IVP embryos during the second week of pregnancy amounted to 26% (heifers) or 34% (parous dairy cows). The length of embryos doubled every day between Days 9 and 16, with a 4.4-fold range in sizes representing two thirds of the variation in length. Embryos retrieved from heifers were twice the size of those incubated in parous cows (P<0.0001), indicating faster embryonic development/trophoblast proliferation in heifers. Whereas season did not affect embryo recoveries, length was lower (50%) in winter (winter-autumn, P<0.05; winter-spring, P<0.001). Lastly, transuterine migration in cattle, when transferring multiple embryos, commenced at Day 14 (4%) and had occurred in all recipients by Day 16 (38% of embryos found contralaterally).
D K Berg; J van Leeuwen; S Beaumont; M Berg; P L Pfeffer
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Theriogenology     Volume:  73     ISSN:  1879-3231     ISO Abbreviation:  Theriogenology     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2009-12-17     Completed Date:  2010-02-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0421510     Medline TA:  Theriogenology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  250-60     Citation Subset:  IM    
AgResearch, Ruakura Campus, Hamilton, New Zealand.
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MeSH Terms
Cattle / physiology*
Cattle Diseases
Embryo Loss / epidemiology,  veterinary*
Embryo Transfer / veterinary
Embryonic Development
Fertilization in Vitro / veterinary
Pregnancy Rate
Risk Factors

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