Analysis of Factors Influencing Somatic Cell Count in Dairy Cow Milk

Abstract

The aim of this study was to evaluate the effects of parity, days in milk (DIM), and season on somatic cell count (SCC) in milk of Holstein dairy cows. The study was conducted on a single dairy farm in eastern Slovakia on 600 cows with an average annual milk yield of 10,317 ± 653 kg, fed a total mixed ration. Cows were grouped according to parity, DIM, and season. Milk composition (protein, fat, lactose) was determined using near-infrared spectrophotometry (MilkoScan FT+), and SCC was measured using Fossomatic FC and Bentley FCM. Parity significantly affected SCC, with the lowest values observed in primiparous cows and a significant increase (P < 0.001) with advancing lactation number; the highest somatic cell count was recorded in the 4 ^th and higher lactations. The effect of days in milk showed increased somatic cell count during early (0–30 days) and peak lactation (31–100 days), followed by the lowest values (P < 0.05). As lactation progressed and milk yield declined, somatic cell count increased, reaching maximum levels after 305 days. Seasonal variation was also significant, with the highest somatic cell count observed in summer (P < 0.001) and the lowest in winter months.