Alternative bedding materials for compost bedded pack barns in Minnesota: A descriptive study

Bedding availability for compost bedded pack barns is a concern for dairy producers who use this type of daily stirred bedded pack housing system. The material most commonly used in these barns is sawdust. The objective of this study was to describe management practices of dairy operations utilizing alternative bedding materials for partial or total replacement of sawdust in their compost barns. This study was conducted on six Minnesota dairy farms having compost bedded packs. Bedding materials used on these farms included: sawdust, wood chips, flax straw, wheat straw, oat hulls, strawdust, and soybean straw. Each farm was visited four times, once each season between January 2008 and November 2008. Replicated samples of the bedded pack material were collected during winter and summer. Samples were analyzed for dry matter, carbon, nitrogen, C:N ratios, ammonium, nitrate, pH, and bacterial counts. Temperatures of each pack were measured seasonally at various depths. Cows were scored for hygiene (1=clean, 5=dirty), body condition (1=thin, 5=obese), and locomotion (1=normal, 5=severely lame), and hock lesions were observed. Aerial ammonia and hydrogen sulfide concentrations, air velocity, and light intensity were measured each season. Overall average aerial ammonia was 3.92 ppm and hydrogen sulfide was 22.8 ppb across all farms and season. Average light intensity was 3,250 lux and air velocity was 0.81 m/s. Bedding pack material averaged 15.8% for total C, 0.93% for total N, 17.8 for C:N ratio, 37.3% for dry matter, 8.83 for pH, 4.25 mg/kg for nitrate, 955 mg/kg for ammonium, 15 g/kg for total potassium, 2.8 g/kg for total phosphorus, 8.5 dS/m for EC, 31.7°C for pack temperature, 7.6°C for outside temperature, and 9.42 million cfu/mL for total bacterial counts in the bedding. Based on these results and our observations, it appears that any of the bedding materials evaluated in this study used to substitute or partially substitute for sawdust can work well in compost dairy barns if the pack is consistently well managed by tilling twice daily, providing proper ventilation to keep surface of pack dry, and adding new material when it is visually adhering to the cows.