Bacteria counts associated with untreated organic bedding materials were compared with those of bedding treated with either an alkaline commercial bedding 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. Each of the bedding treatments significantly reduced bacteria in recycled manure prior to use. The alkaline conditioner and hydrated lime effectively inhibited bacteria in recycled manure for 1 d. Bedding counts and teat swabs of cows housed on recycled manure treated with the alkaline conditioner were reduced on d 2. The use of the acid conditioner in recycled manure had little effect on bacteria in bedding. Sawdust differed from recycled manure in that bacteria in untreated sawdust prior to use were minimal, and populations increased rapidly during the first 2 d after use as bedding. The acid conditioner had a bacteriostatic effect in sawdust, evident by the reduction of bacteria on d 2. The alkaline conditioner and hydrated lime did not alter bacteria counts in sawdust compared with untreated sawdust. Antibacterial activity of each conditioner deteriorated between d 2 and d 6 in both beddings. 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 diminished between d 2 and 6 after use in bedding.

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The effect of an immunization schedule on responses of antibody titers was tested following vaccination with an Escherichia coli J5 bacterin. Eighteen cows were equally distributed among three immunization schedules: 1) subcutaneous injection at 14 d prior to the end of lactation, intramammary immunization at 7 d after drying off, and subcutaneous injection at 30 d into the dry period; 2) subcutaneous injections at drying off, at 30 d into the dry period, and within 12 h after calving; and 3) unimmunized controls. The E. coli J5 bacterin consisted of 5 ml of 10(9) boiled cells/ml of 0.9% NaCl plus 0.005% phenol emulsified with 5 ml of Freund's incomplete adjuvant. Subcutaneous injections were administered on the upper part of the rib cage, posterior to the scapula. Intramammary immunizations of 2.5 ml of bacterin were infused via the teat canal into each of the four mammary glands. Intramammary immunization increased rectal temperatures at 12 h after infusion, but subcutaneous injections did not induce febrile responses. Intramammary immunization enhanced immunoglobulin G titers in serum and whey on d 0 of lactation compared with subcutaneous immunizations. Immunoglobulin G titers in serum also were greater at d 30 of the dry period and at d 14 and 21 of lactation for cows that received intramammary immunization than for cows that were vaccinated by subcutaneous injections only. Immunoglobulin M titers in whey and serum on d 21 of lactation were greater for cows that received intramammary immunizations than for cows that were immunized by subcutaneous injections only.

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