Effects of winter housing system on hygiene, udder health, frostbite, and rumination of dairy cows.

The objective of this study was to evaluate the effects of 2 winter (December to April) housing systems on dairy cow hygiene scores, frostbite, teat condition, clinical mastitis, and activity and rumination across 3 winter seasons (2013, 2014, and 2015). Certified-organic cows (n = 268) were randomly assigned to 2 treatments (2 replicates per system): (1) outdoor straw pack (outdoor) or (2) 3-sided compost-bedded pack barn (indoor). Cows calved during 2 seasons (spring or fall) at the University of Minnesota West Central Research and Outreach Center, Morris, Minnesota, organic dairy. Organic wheat straw was used as bedding for the 2 outdoor straw packs, and bedding was maintained by farm management to keep cows dry and absorb manure throughout the winter. The compost-bedded pack barn (2 pens in the barn) was bedded with organic-approved sawdust, and the bedding material was stirred twice per day with a small chisel plow. Hygiene scores were recorded biweekly as cows exited the milking parlor. Incidence of clinical mastitis was recorded in a binary manner as treated (1) or not treated (0) at least once during a lactation. Frostbite incidence was collected monthly. Activity and rumination times (daily and 2-h periods) were monitored electronically using a neck collar sensor (HR-LD Tags, SCR Dairy, Netanya, Israel). Indoor cows had greater udder hygiene scores (1.75 vs. 1.46) and greater abdomen hygiene scores (1.79 vs. 1.43) compared with outdoor cows. Additionally, the indoor cows had greater upper and lower leg hygiene scores compared with outdoor cows. Incidence of clinical mastitis was greater for indoor cows compared with outdoor cows (27.1% vs. 15.1%, respectively). Frostbite incidence was not different between indoor (30.1%) and outdoor (17.5%) cows. Daily rumination was 509 min/d for indoor cows and 530 min/d for the outdoor cows. In summary, lactating cows housed outdoors on straw-bedded packs had cleaner udders and improved udder health compared with cows housed in a compost-bedded pack barn.