Knowledge of occurrence and prevalence of clots in AMS

What is the incidence of having clots in milk for VMS cows and what are the risk factors? These questions are answered in the paper “Homogeneity density scores of quarter milk in automatic milking systems”, published in Journal of Dairy Science on 11 June 2021.

Homogeneity changes in milk, also called clots, are some of the typical signs of clinical mastitis. The milker will pay attention to this while pre-milking the cows. Due to the nature of automatic milking, there is a lack of knowledge of the occurrence and prevalence of clots for cows milked automatically. For the first time, this has been described by the research team from DeLaval, Charlotte Hallén Sandgren, Dorota Anglart and Ilka Klaas together with researchers from the Swedish University of Agricultural Sciences.

Score, definition and aggregate area of deposits on the filters scored for density:

0 = no sign of clots, none
1 = trace, Ø < 3 mm
2 = mild, Ø ≥ 3 mm
3 = moderate, Ø ≥ 5 mm or approximately 10% covered
4 = heavy, between 10% and 50% covered
5 = very heavy assemble of clots, more than 50% covered

Method and results

The data was collected in 4 VMS farms. All together 21 335 quarter milkings were inspected for clots and scored according to density on a filter. The results showed that most of the milkings (96 %) were free from clots or flakes. Of the samples with changes in the milk, the largest category consisted of “traces” (379 cases), a small flake on the filter that is most likely something that the milker would not take notice of. The results show that the overall incidence of clots, cases that would be of concern for the milker, was very low (2,4 %) and altogether the number of severe cases found was 75. The results showed that these cases were found in a limited group of cows.

Risk factors

The risk of having clots in the milk increased for older cows, cows in early lactation and cows with longer milking intervals. “This is something we need to learn from, as this indicates that risk of having clots could increase twice for fresh cows that won’t go to the VMS to be milked”, says Dorota.

The results from the milk inspections showing the proportion of samples for each quarter milk score (QMS).

“Our newly developed method enables us to investigate not only the occurrence of clots in automatic milking systems. We have seen typical patterns for each cow and identified important risk factors that could be used for better detection of cows with abnormal milk. This knowledge could also contribute to creating applications and services for monitoring udder health and milk quality in the future. We will soon also have a ‘sister paper’ published where we take it to the next step and investigate the possibility to predict the risk of a cow to have clots,” concludes Dorota.

We congratulate the team to the publication in Journal of Dairy Science, from DeLaval Charlotte Hallén Sandgren, former Dairy Development Director, Dorota Anglart, Farm Management Specialist and Ilka Klaas, Dairy Development Director.

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