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Evaluation of three synchrony programs for pasture-based dairy heifers
S McDougall1, F M Rhodes, C W R Compton
1Cognosco, Anexa Animal Health, Morrinsville, New Zealand. smcdougall@anexa.co.nz
Theriogenology
|February 13, 2013
Summary
The Cosynch + P4 program improved conception rates and reduced the time to conception in heifers. This reproductive synchronization strategy also demonstrated the greatest economic benefit compared to other programs.
Area of Science:
- Reproductive endocrinology in livestock
- Dairy cattle management
- Artificial insemination protocols
Background:
- Synchronization programs are crucial for efficient artificial insemination (AI) in dairy heifers.
- Evaluating the efficacy and economic impact of different synchronization protocols is essential for herd management.
- Pubertal status influences reproductive outcomes in heifers.
Purpose of the Study:
- To compare the efficacy and economic benefits of three estrus synchronization programs in pasture-based dairy heifers.
- To assess the impact of pubertal status on reproductive performance within these programs.
Main Methods:
- 1137 heifers were assigned to Double PG, GPG + P4, or Cosynch + P4 treatments.
- Hormonal treatments (GnRH, PGF(2α)) and progesterone (P4) devices were used to synchronize estrus.
- Timed AI was performed, and conception rates, in-calf rates, and time to conception were recorded.
- Plasma P4 concentrations were measured to determine pubertal status.
Main Results:
- Cosynch + P4 resulted in higher conception rates (57%) and 21-day in-calf rates (76%) compared to GPG + P4 (47%, 72%) and Double PG (48%, 63%).
- The Cosynch + P4 group had a shorter median interval to conception (0 days) versus GPG + P4 (14 days) and Double PG (19 days).
- Heifers that reached puberty before breeding showed significantly higher in-calf rates at 21 and 42 days.
Conclusions:
- The Cosynch + P4 synchronization program demonstrated superior fertility and economic advantages in dairy heifers.
- Pubertal status is a significant factor influencing the reproductive success of heifers under different synchronization protocols.
- Implementing the Cosynch + P4 program can enhance reproductive efficiency and profitability in dairy operations.
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