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Journal of Dairy Science Vol. 73 No. 7 1766-1772
© 1990 by American Dairy Science Association ®
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Double Insemination and Gonadotropin-Releasing Hormone Treatment of Repeat-Breeding Dairy Cattle

Jeffrey S. Stevenson 1, Edward P. Call 1, Richard K. Scoby 1, and Arun P. Phatak 2

1 Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506
2 Department of Animal Science, University of California, Davis 95616

Our objective was to determine if double insemmations during the same estrous period of dairy cattle eligible for their third or fourth service (repeat breeders) would improve pregnancy rates equivalent to injections of GnRH given at the time of AI. Repeat-breeding, lactating cows from six herds (five herds in the San Joaquin Valley of central California and one herd in northeast Kansas) were assigned randomly to four treatment groups when detected in estrus: 1) single AI plus no injection, 2) single AI plus 100 µg GnRH at AI, 3) double AI plus no injection, or 4) double AI plus 100 µg of GnRH at AI. Inseminations were performed according to the a.m.–p.m. rule. The second AI for the double AI treatment was given 12 to 16 h after the first AI Injections of GnRH were given intramuscularly immediately following the single AI or the first AI of the double AI. Pregnancy rates of cows given a single AI and hormone injection were numerically higher in all six herds than those of their herdmates given only a single AI. In five of six herds, the pregnancy rates of cows given a double AI and hormone injection were numerically higher than pregnancy rates of their herdmates given only a double AI. Overall pregnancy rates for the four treatments were 1) 112/353 (32.1%), 2) 165/406 (41.6%), 3) 119/364 (33.5%), and 4) 135/359 (37.5%). Gonadotropin-releasing hormone increased pregnancy rates of repeat breeders compared with controls given only a single AI. No further benefit beyond the single AI was accrued from the double AI treatment, with or without concurrent hormone administration.

Key Words: repeat breeders • gonadotropin-releasing hormone • pregnancy rates

Submitted on September 7, 1989
Accepted on January 24, 1990




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M. Kaim, A. Bloch, D. Wolfenson, R. Braw-Tal, M. Rosenberg, H. Voet, and Y. Folman
Effects of GnRH Administered to Cows at the Onset of Estrus on Timing of Ovulation, Endocrine Responses, and Conception
J Dairy Sci, June 1, 2003; 86(6): 2012 - 2021.
[Abstract] [Full Text] [PDF]


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