Publication Database

Impact of estrous expression and interval from estrus alert to synchronization protocol on pregnancy per AI in lactating dairy cows (2025)

Art

Poster

Autoren

Borchardt, S. (WE 19)

Burnett, T. A.

Madureira, A. M. L.

Kongress

ADSA Conference 2025

Louisville, 22. – 25.06.2025

Quelle

Journal of dairy science : JDS

Bandzählung: 108

Heftzählung: Supplement 1

Seiten: 404 – 405

ISSN: 0022-0302

Sprache

Englisch

Verweise

URL (Volltext): https://www.adsa.org/Portals/0/SiteContent/Docs/Meetings/2025ADSA/Abstracts_BOOK_2025_20250624-1249.pdf

Kontakt

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fortpflanzungsklinik@vetmed.fu-berlin.de

Abstract / Zusammenfassung

The aim of this retrospective observational study was to evaluate the effect of estrous expression before the beginning of a synchronization protocol and at the moment of AI on pregnancy per AI (P/AI). A total of 2,842 lactating Holstein cows from 1 commercial herd were enrolled. In yr 1, cows underwent a Double-Ovsynch (DO) protocol for first AI (n = 1,536) and produced a total 305-d milk yield of 13,421 kg, whereas in yr 2, cows followed a presynch-ovsynch (PO) protocol (n = 1,306) and produced 13,868 kg over 305 d. Cows were classified as primiparous or multiparous and continuously monitored using ear-tag accelerometers. Estrus alerts were identified by the system, and intervals from the last alert before synchronizations were categorized as short (SI; 7–14 d) or long (LI; 14–30 d). The total number of alerts from calving to AI was also recorded, with cows categorized as 0, 1, or ≥2 alerts. Pregnancy was confirmed by ultrasonography on d 32 post AI. A logistic regression model assessed associations between estrous expression and P/AI, including estrus at AI, parity, number of alerts, and estrus interval classification. Cow was a random effect, and protocol was a fixed effect. Primiparous cows were more likely to express estrus at AI than multiparous cows (OR 1.79; 95% CI 1.52–2.10). Estrus at AI improved P/AI (OR 1.55; 95% CI 1.32–1.82). For cows showing estrus, P/AI was 65.4% ± 2.4% under DO and 51.1% ± 4.0% under PO. Without estrus, P/AI was 54.4% ± 1.8% and 44.5% ± 3.5% for DO and PO, respectively. Multiparous cows with ≥2 alerts had higher P/AI (OR 1.65; 95% CI 1.10–2.48) than those with 1 alert (OR 1.32; 95% CI 0.98–1.78) or none. No significant difference was found in primiparous cows. LI cows had lower P/AI (OR 0.62; 95% CI 0.51–0.76) than SI cows. Under DO, SI cows had higher P/AI (OR 1.79; 95% CI 1.47–2.17) than LI cows, and under PO, SI cows also showed greater P/AI (OR 1.67; 95% CI 1.30–2.14). In conclusion, cows with SI before synchronization and estrus at AI had improved P/ AI. Continuous monitoring can optimize protocol timing and reduce
blanket treatments through selective management.