Observational study on dry period length and its associations with milk production, culling risk, and fertility in Italian dairy farms

Summary

This observational study of 48,297 lactation records from 62 Italian dairy herds demonstrated that moderate dry period lengths of 50–70 days optimised milk production, culling risk, and fertility outcomes in multiparous cows. Very short dry periods (<40 days) and very long dry periods (>70 days) were associated with reduced milk yield, elevated culling risk (RR 1.53 and 1.46 respectively compared with 50–60 day dry period), and impaired fertility, suggesting that while short dry periods may appeal to high-production herds, they carry considerable management and welfare costs.

Regional applicability

Findings are directly applicable to United Kingdom dairy farms, as herd management practices, lactation physiology, and genetic dairy populations in the UK are similar to those in Italy. The study reinforces evidence-based recommendations for optimal dry period management that are increasingly relevant to UK dairy policy and welfare considerations, particularly as some producers experiment with shortened or no dry period strategies.

Key measures

Dry period length (days, categorised into <40, 40–49, 50–60, 61–70, and >70 d); cumulative milk production at 60 DIM (kg/cow); predicted 305-d milk production (kg/cow); culling risk during first 60 DIM (relative risk); pregnancy risk within 200 DIM (relative risk)

Outcomes reported

The study examined associations between dry period length (DPL) and three key dairy cow outcomes: cumulative milk production at 60 days in milk, culling risk during the first 60 days in milk, and pregnancy risk within 200 days in milk. DPL was classified into five categories and analysed across 48,297 multiparous cow lactation records from 62 Italian dairy herds.

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