Influence of infection on milk production and quality of Holstein dairy cows.

We wished to determine if infection can negatively impact milk quality and production in Holstein dairy cows. For this Research Communication, milk samples (271) from Holstein cows from 3 herds were screened for by real-time PCR. Positive ( = 21) and negative animals ( = 21) were matched by herd, age, lactations and days in milk (DIM). Pairs were evaluated in 7 stages of lactation: D1-50, D51-100, D101-150, D151-200, D201-250, D251-300, and D ≥ 301. A mixed model was used to assess the effect of groups ( × ), time (lactation) and groups × time interaction. Cows positive for had lower average milk production per day and high somatic cells count (SCC).