Prevalence of cows with high-NEFA concentrations during dry period and its relevance to feeding environment: A cross-sectional study in Hokkaido, Japan.

This study aimed to cross-sectionally investigate the prevalence of cows with higher non-esterified fatty acids (NEFA) concentrations and related blood profiles during the dry period, and to evaluate associations between elevated NEFA levels and farm management. Blood samples were collected once from 601 Holstein cows (47 farms) between September 2021 and July 2024, on the day 21-2 before calving, with no disease records within 1 week before sampling. Serum concentrations of NEFA and other metabolites were measured and rumen fill score (RFS; range:1-5) were assessed concurrently. The proportion of high-NEFA cows (NEFA ≥ 0.3 mEq/L) was used to classify herds into control (< 10%, 23 farms), alert (10-25%, 12 farms), and positive (≥ 25%, 12 farms). Farm management data were collected using a structured questionnaire. At the cow level, the prevalence of high-NEFA cows was 16.5% (99/601). No significant differences were observed in the remaining metabolites among the three cow groups. The proportion of cows with RFS ≤ 2 (abnormal low score) was higher in the positive cow group, suggesting insufficient feed intake. Among high-NEFA cows, those with 0-1 parity had a higher incidence of culling within 60 days in milk, whereas ≥ 2 parity cows showed higher incidences of displaced abomasum or clinical ketosis. At the herd level, alert herds had the largest herd size and delayed cow movement after calving. These cow- and herd-level characteristics may be involved with elevated NEFA concentrations.