Document Detail


Pregnancy rates to timed artificial insemination in dairy cows treated with gonadotropin-releasing hormone or porcine luteinizing hormone.
MedLine Citation:
PMID:  19368969     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We compared the effects of porcine luteinizing hormone (pLH) versus gonadotropin-releasing hormone (GnRH) on ovulatory response and pregnancy rate after timed artificial insemination (TAI) in 605 lactating dairy cows. Cows (mean+/-SEM: 2.4+/-0.08 lactations, 109.0+/-2.5 d in milk, and 2.8+/-0.02 body condition score) at three locations were assigned to receive, in a 2x2 factorial design, either 100 microg GnRH or 25mg pLH im on Day 0, 500 microg cloprostenol (PGF) on Day 7, and GnRH or pLH on Day 9, with TAI 14 to 18h later. Ultrasonographic examinations were performed in a subset of cows on Days 0, 7, 10, and 11 to determine ovulations, presence of corpus luteum, and follicle diameter and in all cows 32 d after TAI for pregnancy determination. In 35 cows, plasma progesterone concentrations were determined 0, 3, 4, 5, 6, 7, and 12 d after ovulation. The proportion of noncyclic cows and cows with ovarian cysts on Day 0 were 12% and 6%, respectively. Ovulatory response to first treatment was 62% versus 44% for pLH and GnRH and 78% versus 50% for noncyclic and cyclic cows (P<0.01). Location, ovulatory response to first pLH or GnRH, cyclic status, presence of an ovarian cyst, and preovulatory follicle size did not affect pregnancy rate. Plasma progesterone concentrations after TAI did not differ among treatments. Pregnancy rate to TAI was greater (P<0.01) in the GnRH/PGF/pLH group (42%) than in the other three groups (28%, 30%, and 26% for GnRH/PGF/GnRH, pLH/PGF/GnRH, and pLH/PGF/pLH, respectively). Although only 3% of cows given pLH in lieu of GnRH on Day 9 lost their embryo versus 7% in those subjected to a conventional TAI using two GnRH treatments, the difference was not statistically significant. In summary, pLH treatment on Day 0 increased ovulatory response but not pregnancy rate. Cows treated with GnRH/PGF/pLH had the highest pregnancy rate to TAI, but progesterone concentrations after TAI were not increased. In addition, preovulatory follicle diameter did not affect pregnancy rate.
Authors:
M G Colazo; M B Gordon; R Rajamahendran; R J Mapletoft; D J Ambrose
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-04-14
Journal Detail:
Title:  Theriogenology     Volume:  72     ISSN:  1879-3231     ISO Abbreviation:  Theriogenology     Publication Date:  2009 Jul 
Date Detail:
Created Date:  2009-06-22     Completed Date:  2009-09-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0421510     Medline TA:  Theriogenology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  262-70     Citation Subset:  IM    
Affiliation:
Dairy Research and Technology Centre, Alberta Agriculture and Rural Development, Edmonton, AB, Canada.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cattle / physiology*
Dinoprost / administration & dosage
Female
Gonadotropin-Releasing Hormone / administration & dosage*
Insemination, Artificial / methods,  veterinary*
Lactation
Luteinizing Hormone / administration & dosage*
Ovary / ultrasonography
Ovulation Induction / methods,  veterinary
Pregnancy
Swine
Time Factors
Chemical
Reg. No./Substance:
33515-09-2/Gonadotropin-Releasing Hormone; 551-11-1/Dinoprost; 9002-67-9/Luteinizing Hormone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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