Effects of bedding with recycled sand on lying behaviors, udder hygiene, and preferences of lactating Holstein dairy cows

Effects of bedding with recycled sand and season on lying behaviors, stress, hygiene, and preferences of late-lactation Holstein cows were studied. Cows (n=64) were divided into 4 groups (n=8 per group) per season. In summer (Aug-Sept), cows were balanced by days in milk (268.1±11.9 d) and parity (2.0±0.2). In winter (Jan-Feb), mean DIM was 265.5±34.1 d. Cows were assigned to one of two treatments (trt) using a crossover design with each trt lasting 7-d (no-choice phase): bedding with recycled sand (RS; n=32) or control (CO; clean sand; n=32). Stocking density was maintained at 100%. Choice phase allowed a cow to have each treatment. Accelerometers recorded daily lying time/d, number of lying bouts/d, lying bout duration (min/bout), and total steps/d. Blood, teat swabs, milk, sand samples, and udder hygiene scores were collected on d 0, 3, and 7 of each experimental week. Blood was used to assess levels of cortisol. Samples were cultured for Streptococci, Staphylococci, and gram-negative bacteria. Video data was used to assess bedding preferences. All data were analyzed using the MIXED and GLIMMIX procedures of SAS 9.3. Lying time was not affected by treatment, but there was an increase in steps during winter. Cortisol was higher for control cows in summer and recycled sand in winter. Bacterial counts were higher for cows on recycled sand. Hygiene scores were higher for cows on recycled sand during the summer. There was not a preference for control or recycled sand.