Bacterial counts associated with sawdust and recycled manure bedding treated with commercial conditioners

Bacteria counts associated with untreated organic bedding materials were co mpared with those of bedding treated with either an alkaline commercial bed ding conditioner, acidic commercial bedding conditioner, or hydrated lime. Bedding materials were recycled manure and kiln-dried sawdust. The effects of bedding treatments on bacteria counts differed between bedding types. Ea ch of the bedding treatments significantly reduced bacteria in recycled man ure prior to use. The alkaline conditioner and hydrated lime effectively in hibited bacteria in recycled manure for 1 d. Bedding counts and teat swabs of cows housed on recycled manure treated with the alkaline conditioner wer e reduced on d 2. The use of the acid conditioner in recycled manure had li ttle effect on bacteria in bedding. Sawdust differed from recycled manure i n that bacteria in untreated sawdust prior to use were minimal, and populat ions increased rapidly during the first 2 d after use as bedding. The acid conditioner had a bacteriostatic effect in sawdust, evident by the reductio n of bacteria on d 2. The alkaline conditioner and hydrated lime did not al ter bacteria counts in sawdust compared with untreated sawdust. Antibacteri al activity of each conditioner deteriorated between d 2 and d 6 in both be ddings. The antibacterial activities of conditioners were related to the pH of bedding materials. The use of commercial bedding conditioners initially reduced bacterial counts; however, the antibacterial effects had diminishe d between d 2 and 6 after use in bedding.