Title page for ETD etd-04292005-114027


Type of Document Master's Thesis
Author Cornwell, Jeffrey M
URN etd-04292005-114027
Title The Interaction of Sire Fertility and Timing of AI in a Synchronization Protocol
Degree Master of Science
Department Dairy Science
Advisory Committee
Advisor Name Title
Nebel, Raymond L. Committee Chair
Akers, Robert Michael Committee Member
Kasimanickam, Ramanathan Committee Member
McGilliard, Michael L. Committee Member
Keywords
  • CIDR
  • resynchronization
  • sire fertility
  • ERCR
Date of Defense 2005-04-22
Availability restricted
Abstract
The Interaction of Sire Fertility and Timing of AI in a Synchronization Protocol

J. M. Cornwell

ABSTRACT

The objectives of this study were to determine if fixed-timed artificial insemination (FTAI) at two different times, 0 or 24 h after GnRH administration, in a Presynch-Ovsynch protocol influenced the pregnancy rate (PR) when average and high fertility sires were used. Additionally, a second experiment was conducted to determine the effectiveness of CIDR inserts to allow for resynchronization of estrus in cows that did not conceive or maintain the conceptus at FTAI. Lactating Holstein cows (n = 1,457) from two well-managed dairy herds located in the piedmont region of North Carolina were utilized for 12 mo. First artificial insemination (AI) PR differed for fertility group and was 24.1 and 29.2% for average and high fertility group, respectively. Timing of AI did not influence first AI PR and there was no interaction of fertility group and timing of AI. Cows that received a CIDR insert were detected more frequently in estrus during a 4 d period, d 21 to 24, than control cows, 92.5 and 62.0%, respectively. However, the CIDR insert did not increase the detection of estrus compared to control cows over a normal estrus return interval of 7 d, 18 to 24 d after GnRH administration of a FTAI protocol, 28.8 and 34.2% respectively. In conclusion, the use of high fertility sires is a practical recommendation for improving first AI PR and CIDR inserts allowed more cows to be detected in estrus during a shorter interval, but did not increase the estrus detection rate during a normal estrus return interval.

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