Observational study of temperature, moisture, pH and bacteria in straw bedding, and faecal consistency, cleanliness and mastitis in cows in four dairy herds

Abstract

A study of four dairy farms showed that much of the straw stored for bedding was too wet (over 15 per cent moisture content). Most of the beds, including their top surfaces, were damp (above 75 per cent relative humidity). The temperature of the surface of most of the straw beds was related to the air temperature, many being below 15°C, but below the surface the temperatures of most beds reached between 15°C and 45°C within about a week of their being renewed. Bacterial counts also reached a plateau within one to two weeks. The pH of the top layers of straw was usually between 8.5 and 9.5. Adding lime daily to the top layer of the straw failed to raise the pH to levels at which Escherichia coli and Streptococcus uberis do not survive. Most of the counts of E coil and faecal streptococci in the top layers of straw were above 106 colony-forming units/g. Counts of E coli and S uberis were much higher in the beds of early lactation cows than in those of dry cows. Many of the early lactation cows were heavily and persistently contaminated with faeces. Dry cows were much cleaner. Groups of cows with firmer faeces were also cleaner. The farm with the lowest incidence of mastitis had the cleanest cows and the most satisfactory beds.