Udder infections reduced in Finland
The incidence of udder infections was determined on the basis of cell count data for individual cows extracted from production survey material in 1991, 2001 and 2010. At the same time, the effect of factors attributable to the whole herd or individual cows on the occurrence of udder infections was examined. In 2010, the proportion of cows with udder infections of all cows studied was 19 per cent, in 2001 it was 20 per cent, and ten years earlier 22 per cent. The reduction is statistically highly significant.
More udder infections in loose housing systems
The research showed that the incidence of udder infections was higher in loose cattle housing systems, than in stall or box cowhouses where the cows are tethered. There were more udder infections on farms with more than 60 cattle than on smaller farms. As the average production of the farm went up, the incidence of udder infections also went down. Organic farms had more udder infections than customary farms. The incidence of udder infections increased with the number of calvings exceeding two. The udder health of Holstein-Friesians was not so good as that of Ayrshire cows. Similarly, farms with automatic milking systems had more udder infections than other farms.
Management of udder health remains one of the great challenges of dairy farming, requiring determined work by all operators.
Risk factors of udder infections
Dairy cattle husbandry has changed considerably: from the 1991 level (5,725 kg/y), average production grew by 2010 to almost 9,000 kg/y. At the same time, the number of dairy farms has fallen to a quarter. Automated milking has been adopted: in 2001 there were 9 farms in Finland with automatic milking systems, but by 2010 the number had reached 576 farms.
The proportion of cows with prolonged raised somatic cell counts (SCC) or those with chronic udder infections has increased over the last decade. The proportion of cows with chronic infections rose between 2000 and 2010 to 16 per cent, whereas it had previously fallen between 1991 and 2000 from 20 per cent to 15 per cent.
The increase in cows with chronic infections may be explained by farms increasing their stock numbers not being able to eliminate animals producing milk with high cell count. On the other hand, the declining proportion of cows with udder infections with growth in the farm’s average production may reflect the production becoming more professional and improved management of udder health.
Study based on production survey
The material of the survey comprised 272,749 cows in 2010, 337,314 cows in 2001 and 122,402 cows in 1991. The number of subjects in the 1991 material was less than 30 per cent of all dairy cows, but in the latter survey years it already covered about 95 per cent. A cow with an udder infection was defined as a cow producing milk with a cell count exceeding 200,000 cells/ml at the first test milking of the year. Cows with cell counts exceeding this limit at the minimum of three out of four test milkings were defined as suffering from chronic udder infections.
Several surveys on the incidence of udder infections have been conducted in Finland previously, but their results are not directly comparable to this study due to differences in methods and definitions of udder infections.
The study was financially supported by the Walter Ehrström Foundation.
Heidi Hiitiö, Liceniate of Veterinary Medicine, University of Helsinki Faculty of Veterinary Medicine, Department of Production Animal Medicine
Professor Sinikka Pelkonen, Veterinary Bacteriology Research Unit, Evira