Document Detail

Reducing the interval from presynchronization to initiation of timed artificial insemination improves fertility in dairy cows.
MedLine Citation:
PMID:  17699039     Owner:  NLM     Status:  MEDLINE    
The objective was to determine if reducing the interval from presynchronization to the first GnRH injection (G1) of a timed artificial insemination (AI) protocol improves pregnancy per AI. One thousand two hundred fourteen Holstein cows, at 37 +/- 3 d in milk (DIM), were stratified by parity, DIM, and milk yield in the first month postpartum and randomly assigned to control (n = 412), 2 injections of PGF2alpha at 37 +/- 3 and 51 +/- 3 DIM, then enrolled in a timed AI protocol 14 d later; PShort (n = 410), 2 injections of PGF2alpha at 40 +/- 3 and 54 +/- 3 DIM, then enrolled in a timed AI protocol 11 d later; or PShortG (n = 392), same as PShort, but with an injection of GnRH 7 d before G1. All cows received the same timed AI protocol (d 65, G1; d 72, PGF2alpha; d 73, 1 mg of estradiol cypionate; d 75, AI). A subset of 1,000 cows had their ovaries examined by ultrasonography at G1 and 7 d later when PGF2alpha of the timed AI was given to determine presence of corpus luteum (CL) and ovulation to G1. Pregnancy was diagnosed on d 38 after timed AI, and pregnant cows were reevaluated for pregnancy 4 wk later. Altering the interval between presynchronization and G1 did not affect the proportion of cows with a CL at G1, but GnRH 7 d before G1 increased the proportion of cows with a CL. Ovulation to G1 was greater for 11 compared with the 14 d interval, but GnRH did not improve ovulation. The increased ovulation to G1 when the interval was reduced from 14 to 11 d was observed only in cows with a CL at G1, but treatment did not affect ovulation in cows without a CL at G1. Treatment affected the pregnancy per AI on d 38 and 66 after insemination, and they were greater for the 11 compared with 14-d interval, but addition of GnRH did not improve pregnancy per AI. Cows ovulating to G1 had greater pregnancy per AI regardless of whether or not they had a CL at G1. Reducing the interval from presynchronization to initiation of the timed AI protocol from 14 to 11 d increased ovulation to G1 and pregnancy per AI in lactating dairy cows.
K N Galvão; M F Sá Filho; J E P Santos
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of dairy science     Volume:  90     ISSN:  1525-3198     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2007 Sep 
Date Detail:
Created Date:  2007-08-16     Completed Date:  2007-10-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4212-8     Citation Subset:  IM    
Veterinary Medicine Teaching and Research Center, University of California-Davis, Tulare 93274, USA.
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MeSH Terms
Cattle / physiology*
Dinoprost / administration & dosage
Estradiol / administration & dosage,  analogs & derivatives
Estrus Synchronization / methods*
Gonadotropin-Releasing Hormone / administration & dosage
Insemination, Artificial / methods,  veterinary*
Ovary / ultrasonography
Time Factors
Reg. No./Substance:
313-06-4/estradiol 17 beta-cypionate; 33515-09-2/Gonadotropin-Releasing Hormone; 50-28-2/Estradiol; 551-11-1/Dinoprost

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

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