Association between Hygienic Milk Quality and Culling Rate or Mortality in Dairy Herds: A Cross-Sectional Study in Eastern Hokkaido, Japan                    

Akira GOTO, Mitsuo YOKOI, Naoki YAMAMOTO, Kenji KUTARA, Yoichi INOUE, Keiichi HISAEDA, Yasunori SHINOZUKA and Ken NAKADA

Abstract16
This study analyzed production records from Hokkaido, Japan to develop a plan for farmers to17
improve milk quality. Over three years, 164 dairy herds were evaluated based on two milk quality18
indices: herd-level somatic cell count and chronic subclinical mastitis morbidity. Farms were19
ranked annually for each index, and the rankings were combined to determine an overall20
evaluation. After a comprehensive assessment, the herds were categorized into three groups:21
excellent (36 herds), good (90 herds), and poor (38 herds). A comparative analysis of nine22
production indices, including milk quality, was conducted between the excellent and poor groups.23
Our study revealed that poor herds exhibited significantly smaller herd sizes, higher culling rates24
at specific periods, higher mortality, and a greater proportion of dead cows among culled cows25Advance Publication by J-STAGEJapan Agricultural Research Quarterly: JARQ
than excellent herds. The increased mortality in poor herds suggests lower animal welfare26
standards. Furthermore, the high rate of involuntary culling indicates suboptimal peripartum27
management. These findings underscore the strong link between poor milk quality and28
compromised animal welfare. The results suggest that improving animal welfare practices can29
lead to higher milk quality in dairy herds.

Japan Agricultural Research Quarterly