Document Detail

Evaluation of short estrus synchronization methods in dairy cows.
MedLine Citation:
PMID:  18276087     Owner:  NLM     Status:  MEDLINE    
In the present study, two new short estrus synchronization methods have been developed for lactating dairy cows. The study was completed in three consecutive phases. In experiment (Exp) 1, 32 cows, that were not detected in estrus since calving between the 50th and 84th post-partum days, were treated with PGF2alpha (PGF, d-cloprostenol, 0.150 mg), estradiol propionate (EP, 2mg) and GnRH (lecirelina, 50 microg) at 24h intervals, respectively, and timed artificial insemination (TAI) was performed 48 h after PGF. Different from Exp 1, EP and GnRH were given at 48 and 60 h, respectively after PGF in Exp 2 (n=20), instead of 24 and 48 h. Ovulations were investigated by ultrasound for 7 days starting from the day of PGF treatment, and ovulation rates were compared with the ones obtained in Exp 1. In Exp 3, cows were given the same treatments as Exp 2, but treatments started at certain estrus stages. Cows detected in estrus and with a confirmed ovulation (n=27) after the second PGF given 11 days apart were assigned to three treatment groups. Treatment was initiated at Day 3 (group metestrus, n=9), Day 12 (group diestrus, n=9) and Day 18 (group proestrus, n=9) after ovulation. All cows included in Exp 3 were TAI between 16 and 20 h after GnRH treatment. In Exp 2 and 3, blood samples were obtained once every 2 days, starting from Day 0 to the 10th day after GnRH injection, and once every 4 days between the 10th and the 22nd days after GnRH to examine post-treatment luteal development. During the study, animals exhibiting natural estrus were inseminated and served as controls (n=85). The rate of estrus was found to be significantly higher in cows with an active corpus luteum (CL) at the start of Exp 1 (72.7% vs. 30.0%, P<0.05) and the pregnancy rate tended to be higher than cows without an active CL (40.9% vs. 10.0%, P=0.08). Compared to those in Exp 1, cows in Exp 2 had higher rates of synchronized ovulation (94.1% vs. 59.1%, P=0.013). In Exp 3, estrus (P<0.001) and pregnancy rates (P=0.01) were found to be significantly higher in cows in the proestrus group than in those in the metestrus group. Comparable pregnancy rates were obtained from the first and second inseminations in Exp 1 and 3 with results from those inseminated at natural estrus (P>0.05). It was concluded from the study that the treatment in Exp 1 and 3 could result in comparable pregnancy rates after timed AI of lactating dairy cows at random stages of the estrus cycle relating to those inseminated at natural estrus, but the stage of the estrus cycle can have significant effects on pregnancy rates.
Umüt Cirit; Suleyman Bacinoglu; Muzaffer Taş; Kamber Demir; Ahmet Baş; Kemal Ak; Irfan Kamuran Ileri
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-12-28
Journal Detail:
Title:  Animal reproduction science     Volume:  109     ISSN:  1873-2232     ISO Abbreviation:  Anim. Reprod. Sci.     Publication Date:  2008 Dec 
Date Detail:
Created Date:  2008-10-30     Completed Date:  2008-12-31     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7807205     Medline TA:  Anim Reprod Sci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  65-76     Citation Subset:  IM    
Department of Reproduction and Artificial Insemination, Faculty of Veterinary Medicine, Istanbul University, Istanbul, Turkey.
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MeSH Terms
Corpus Luteum / drug effects,  physiology
Dinoprost / pharmacology
Estradiol / pharmacology
Estrus / physiology*
Estrus Synchronization / methods
Gonadotropin-Releasing Hormone / pharmacology
Insemination, Artificial / methods,  veterinary
Melengestrol Acetate / pharmacology
Ovulation / drug effects,  physiology
Time Factors
Reg. No./Substance:
2919-66-6/Melengestrol Acetate; 33515-09-2/Gonadotropin-Releasing Hormone; 50-28-2/Estradiol; 551-11-1/Dinoprost

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