Epsilon Archive for Student Projects

Abstract

På senare år har problem med falskt förhöjda eller uteblivna celltalsvärden uppmärksammats vid analys av svenska provmjölkningsprover. Problemet misstänks bero på otillräcklig separation mellan somatiska celler och bakgrundsbrus vid analysen, vilket i detta arbete benämns som cellsönderfall. Syftet med studien var att undersöka förekomsten av cellsönderfall i svenska provmjölkningsprover samt analysera samband mellan cellsönderfall och individ- och besättningsfaktorer. Studien baserades på data från Eurofins och Växas kodatabas. Besättningsdata från åren 2022–2025 användes för analyser på besättningsnivå och individdata från 2025 användes för analyser på konivå. Statistiska analyser genomfördes i Stata med hjälp av deskriptiva analyser och logistiska regressionsmodeller. Resultaten visade att andelen prover med cellsönderfall var låg (<1 %), men att en stor andel besättningar hade minst ett prov med cellsönderfall under studieperioden. Förekomsten varierade mellan olika mjölkningssystem, där besättningar med

In recent years, falsely elevated or missing somatic cell count values have been reported in Swedish milk recording samples. The problem is believed to be caused by insufficient separation between somatic cells and background noise during analysis, a phenomenon referred to as cell lysis in this study. The aim of the study was to investigate the occurrence of cell lysis in Swedish milk recording samples and to analyse associations between cell lysis and both cow- and herd-level factors. The study was based on data from Eurofins and Växa’s database. Herd-level data from 2022–2025 were used for herd-level analyses, while individual cow data from 2025 were used for cow-level analyses. Statistical analyses were performed in Stata using descriptive analyses and logistic regression models. The results showed that the proportion of samples with cell lysis was low (<1%), although a large proportion of herds had at least one affected sample during the study period. The occurrence varied between milking systems, with herds using automatic milking systems showing the highest probability of cell lysis. Organic and larger herds also showed a higher probability. At the cow level, associations were observed with breed, parity, BHB and milk yield. Seasonal variation and geographical differences between counties were also observed. In conclusion, the study indicates that cell lysis is a complex phenomenon likely influenced by several interacting factors related to both herd management and the physiological status of the cow. The results contribute to increased knowledge of a phenomenon that may affect the reliability of somatic cell count analyses and thereby the monitoring of udder health in Swedish dairy herds.