Effect of bedding conditioners on bacteria counts and pH in shavings, digested manure solids and recycled sand bedding

Abstract

A controlled trial was conducted in 16 commercial dairy herds to describe the effect of an alkalinizing (A) and an acidifying (B) bedding conditioner on bedding pH and bacterial counts when applied twice per week to stalls containing shavings (SH), digested manure solids (DS) or recycled sand (RS) bedding materials. Bedding pH and bacterial counts were measured in samples collected one day, and again in three to four days, after new conditioner was applied to the stalls. Conditioners A and B had an alkalinizing and acidifying effect, respectively, on bedding pH. Although conditioner A reduced coliform bacterial counts by between 0.7 and 1.6 logs in RS and DS bedding for one day and it had no effect on Klebsiella spp. or Streptococcus spp. bacterial counts in these bedding materials. Activity against coliform bacterial counts did not persist for three to four days. Conditioner A reduced bacterial counts in SH by between 0.3 to 1.3 logs for at least one day, but had no persistent activity for three to four days when stalls were rebedded. Conditioner B did not reduce bacterial counts in either DS or RS bedding, and actually increased Klebsiella spp. bacterial counts in DS. However, conditioner B reduced bacterial counts in SH for one day (0.4 to 1.8 log reduction, depending on the bacteria group), with antibacterial activity persisting for three to four days post-application (0.4 to 0.6 log reduction), even though stalls had been rebedded in the interval between conditioner application and collection of the day 3 to 4 bedding samples. For all bedding materials studied, bacterial counts were significantly lower in stalls for which fresh bedding had been added within the previous 24-48 hours. The magnitude of reduction in bacterial counts associated with having recently bedded stalls (approximately 1.6, 0.6, and 1.6 log reduction in coliform, Klebsiella spp., and Streptococcus spp. bacteria, respectively) was, on average, greater than the magnitude of reduction in bacterial counts attributed to the bedding conditioner treatments being studied. These findings suggest that the alkalinizing conditioner A will not be useful on commercial dairies, regardless of bedding type in use, if applied only twice per week in accordance with manufacturer recommendations. The acidifying conditioner B will not be useful on commercial dairies using DS or RS bedding, but may be useful to reduce bacterial counts in SH bedding. Finally, findings suggest that producers can significantly reduce bacterial exposure to teat ends simply by applying fresh bedding to stalls on a more frequent basis.