Effect of cow cleanliness in different housing systems on somatic cell count in milk

Anotace: The aim of the study was to analyse the effect of the housing system (tie-stall vs free-stall) on cow cleanliness, and the effect of the degree of cow dirtiness on the milk somatic cell count. Over 33% of the cows were found to be clean, with more of them in the free-stall barn. Analysis of the cleanliness of body parts showed that the highest hygiene level was characteristic of the udders and underbelly (scores of 1 for 47% and 56% of the cows, respectively). In the free-stall barn, there were over twice as many cows with clean udders (58%) and almost twice as few cows with very dirty udders. Regardless of the housing system, the degree of udder dirtiness created differences (P ≤ 0.01) in the natural log somatic cell count. The natural log somatic cell count increased from 11.54 to 12.37 on average with increased dirtiness of the udder. Greater differences in the cytological quality of milk were found in cows housed in the free-stall system. When analysing the effect of overall dirtiness of the cows and the body parts on the percentage of SCC classes, it was found that highest quality milk (< 200 000 somatic cells/ml) was produced by clean cows (71.52%). The proportion of cows with subclinical and clinical mastitis was found to increase with decreasing cleanliness of the udder, especially in the free-stall system. Overall, the proportion of cows with clinical mastitis increased from 2.51% (clean cows) to 14.29% (dirty cows).