Synchronization of ovulation based on stages of follicular and corpora lutea development in lactating dairy cows diagnosed not-pregnant
Cows that fail to conceive to 1st or subsequent inseminations are a major reproductive problem on dairy farms and commonly used re-synchronization programs are not as effective as pre-synch/Ovsynch programs for 1st AI. Ovsynch appears to be most effective when initiated during the 1st follicular wave of an estrous cycle when the dominant follicle is responsive to the 1st GnRH allowing the PGF2&alpha to be administered prior to natural luteolysis. Yet, most cows are in other stages of follicle and CL development at time of a not-pregnant diagnosis. Pre-synchronization programs are designed to synchronize cows that are in these other stages of follicle and CL development to the 1st follicular wave. The objective of this thesis was to test 3 re-synchronization programs (Ovsynch, G6G, and GGPG) tailored to 4 different stages of follicular and corpora lutea development in cows (n = 515) that did not become pregnant at 1st AI in order to synchronize cows to the 1st follicular wave at the start of Ovsynch. Conception rates were 27.8, 36.6, and 45.3% for Ovsynch, G6G, and GGPG, respectively, and were not statistically different. Heart girth measurements indicated that smaller cows had greater rates of luteolysis following the final PGF2&alpha of Ovsynch and a tendency for higher conception rates in cows with a mature CL. This could potentially be an artifact of incorrect dosage of PGF2&alpha and GnRH used in synchronization protocols. In Chapter 4, the relationship between linear type traits and reproduction in 2299 cows was examined. Cows with increased body volume traits (strength and body depth) consistently had poorer fertility, which agrees with our findings in Chapter 3.
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- In Collections
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Electronic Theses & Dissertations
- Copyright Status
- In Copyright
- Material Type
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Theses
- Authors
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Kron, Megan
- Thesis Advisors
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Pursley, James R.
- Committee Members
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Ames, Kent
Grooms, Dan
Cibelli, Jose
- Date Published
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2011
- Program of Study
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Animal Science
- Degree Level
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Masters
- Language
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English
- Pages
- x, 67 pages
- ISBN
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9781124651989
1124651985
- Permalink
- https://doi.org/doi:10.25335/tebk-sf20