Document Detail

Plasma progesterone concentrations during early pregnancy in spring- and autumn-bred ewes.
MedLine Citation:
PMID:  18467044     Owner:  NLM     Status:  MEDLINE    
The objective of this experiment was to measure blood progesterone concentrations during early gestation to determine if the apparent reproductive failure in ewes bred out-of-season is due to a failure to conceive or embryonic loss. Blood samples were collected from spring- (n=61) and autumn-bred ewes (n=29) from Days 8 to 39 post-oestrus. Serum progesterone concentrations were analysed to ascertain whether ewes were ovulating and failing to maintain pregnancy, or conception was failing. Following pregnancy diagnosis 62 days after ram introduction, ewes were categorised as; no display of oestrus, mated but then identified as non-pregnant, or pregnant. A majority of spring-bred ewes that failed to display oestrus had silent oestrus (86%) and 66% of those ewes had abnormally short-lived corpora lutea. Circulating progesterone concentrations during dioestrus in ewes that had ovulated and displayed oestrus were unaffected by season. Similarly, progesterone concentrations during dioestrus did not differ between pregnant and mated non-pregnant ewes. The results indicated that while early luteylosis, low progesterone secretion from corpora lutea and embryo mortality did occur, these were in only a small proportion of ewes. Progesterone concentrations indicated that a majority of mated non-pregnant ewes had elevated progesterone concentrations necessary for the production of at least one viable embryo/foetus. This may be indicative to the failure of maternal recognition of pregnancy, and it is recommended that events surrounding this stage of pregnancy (Days 12-14) be examined more closely in ewes during the non-breeding season.
G deNicolo; T J Parkinson; P R Kenyon; P C H Morel; S T Morris
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-03-30
Journal Detail:
Title:  Animal reproduction science     Volume:  111     ISSN:  1873-2232     ISO Abbreviation:  Anim. Reprod. Sci.     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-02-09     Completed Date:  2009-05-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7807205     Medline TA:  Anim Reprod Sci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  279-88     Citation Subset:  IM    
Massey University, Palmerston North, New Zealand.
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MeSH Terms
Embryo Loss / blood,  veterinary
Estrus / blood
Pregnancy, Animal / blood*
Progesterone / blood*
Sheep / blood*
Reg. No./Substance:

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