A Short Presynchronization with PGF2α and GnRH Improves Ovarian Response and Fertility in Lactating Holstein Cows Subjected to a Heatsynch Protocol
Bibliographic record
Abstract
Abstract The objective of this study was to assess the efficacy of a single injection of Prostaglandin F2α (PGF2α) combined with or without GnRH before initiation of a Heatsynch protocol (GnRH-7d- PGF2α-2d-EB-1d-AI) on ovarian response and fertility in lactating Holstein cows. A total of 252 cows with a corpus luteum (CL; ≥10 mm) were assigned to one of three synchronization groups; 1 - Control (n=84), cows received two injections of PGF2α 14 days apart; 2 - Heatsynch with GnRH (PGH, n=88) the cows received PGF2α followed by GnRH four days later and then a Heatsynch protocol was initiated eight days after GnRH treatment; and 3 - Heatsynch without GnRH (PH, n=80) cows received a single injection of PGF2α followed by a Heatsynch protocol initiated 12 days after PGF2α. Cows detected in estrus were inseminated approximately 12 h after onset of estrus. Ovarian response and pregnancy diagnosis were determined by ultrasonography during the synchronization protocol and 30 days after AI, respectively. Results showed the percentage of cows with plasma P4≤0.4 ng/mL at AI were greater in PGH group compared to other groups (90.3 vs. 75.0%, P=0.03). The percentage of cows that ovulated in response to the GnRH injection of Heatsynch was affected (P<0.01) by synchronization protocol, because PGH cows were more likely to ovulate (77.2%) than PH (56.0%) cows. The proportion of cows displaying estrus was greater in PGH (70.4%) and PH (72.5%) groups compared with control (47.0%, P=0.04). Percentage of cows pregnant at 30 days after AI was (P=0.01) affected by synchronization treatment and was greater in PGH (45.16%) compared to control (25.0%) and PH (34.48%) groups. In summary, a short presynchronization that includes an injection of PGF2α and four days later GnRH increased fertility in Holstein cows subjected to a Heatsynch protocol. The enhanced fertility was due to a greater ovulatory response to GnRH of Heatsynch, more adequate plasma P4 concentrations during follicle development and a greater luteal regression following PGF2α prior to AI.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".