Abstract
The objectives were to quantify bedding concentrations of total bacteria and selected groups of mastitis pathogens (coliforms and streptococci), to identify bedding factors associated with these bacterial populations, and to describe longitudinal variation of bedding characteristics. Bedding samples from the superficial and deep (20 cm) layers were collected biweekly during 1 year from 3 compost bedded pack (CBP) dairies. Bedding bacterial concentrations and physical-chemical characteristics (moisture, organic matter, carbon-nitrogen ratio (C/N), pH, and density) were determined. Mixed models were used to identify predictors for bacterial concentrations. Shewhart control charts were produced to describe longitudinal variation of bedding characteristics and define alerts of out-of-control variation. Bedding temperature was greater in the deep layer than on the surface (difference = 27.0, 12.1, and 14.4 °C for farms A, B and C, respectively). Except for farm B, bacterial concentrations were greater on the surface than in the deep layer. Organic matter and dry density were associated with concentration of total bacteria and coliforms. For all farms, C/N (positive association) and dry density (negative association) were associated with bedding concentration of streptococci. Deep temperature and moisture remained within the control limits defined in farm A and B during most of the period, whereas 7 and 9 alerts for temperature and moisture were observed on farm C, respectively. For all farms, organic matter, C/N, and pH exhibited great variation, resulting in several out-of-control alerts. Results of this study can be used to manage the CBP towards reducing cows’ exposure to mastitis pathogens.
Highlights
The compost bedded pack system (CBP) has been increasingly used worldwide to house dairy cows
Due to the organic nature of the bedding, one of the main concerns for housing cows in the CBP is the potential increase in exposure to environmental mastitis pathogens
Results of recent studies indicated that temperatures observed in the deep layers of the CBP (< 48.1 °C) are not high enough to substantially decrease bacterial concentrations in the material (Barberg et al, 2007; Shane, Endres, & Janni, 2010; Black et al, 2014)
Summary
The compost bedded pack system (CBP) has been increasingly used worldwide to house dairy cows. The CBP is based on principles of traditional composting, in which organic materials are degraded by means of aerobic microbiological decomposition (Janni, Endres, Reneau, & Schoper, 2007). The CBP barns are bedded with an organic substrate (such as sawdust), to which feces and urine are constantly added by cows. Bedding is aerated twice a day between milking time to incorporate animal waste and ensure that the composting process continues aerobic and results in a comfortable, dry, and clean bedding surface to the animals. New bedding material is added systematically and after periods as long as 1 year, the bedding can be entirely replaced and used as fertilizer (Barberg, Endres, & Janni, 2007; Janni et al, 2007)
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