Full explanation
Structure: (1) GESTATION — 280 days (9 months 10 days), biologically fixed; (2) DRY PERIOD — 60 days pre-calving for udder renewal (<45 days — fat drops 0.3–0.5% and protein 0.1–0.2%; >75 days — obesity and ketosis risk); (3) SERVICE PERIOD (days open) — time from calving to successful insemination, target 60–90 days, Ukraine reality 90–140 days. +10 days CI = −1.1% annual ECM yield. Causes of long CI in Ukraine: (1) poor heat detection (40–60% without automation), (2) subclinical acidosis/ketosis (unbalanced TMR), (3) post-calving metritis, (4) economic stress. Monitoring: Dairy Herd Improvement (DHI) monthly reports, KPI «pregnancy rate» — target 25–30%, Ukrainian average 15–20%. For 200+ head farms a reproduction manager is mandatory.