VETERINARSKI ARHIV, vol.94, no.1, pp.22-32, 2024 (SCI-Expanded)
Globally, the milk yield of Holstein cows has increased considerably, but this situation has reduced the cows’
tolerance to environmental factors and, thus, it has negatively affected udder health and milk quality. This study aimed
to determine the influence of somatic cell count (SCC) on milk yield and its composition in early (<100 days), mid
(100–200 days), and late lactation (>200 days) between November 2019 and August 2020. The study material consists
of 927 records of 132 Holstein cows raised on a commercial dairy cattle farm in the Kırşehir province of Turkey. SCC
was categorized into three groups (<100x103
cell/mL, 100-200x103
cell/mL, and >200x103
cell/mL). SCC data were
logarithmically transformed to log10 base. In the study, logSCC, test day milk yield (MY), fat content (FC), solidsnot-fat (SNF), protein content (PC), lactose content (LC), fat yield (FY), and protein yield (PY) were recorded as
5.12±0.01, 37.54±0.34 kg, 3.59±0.02%, 9.08±0.01%, 3.35±0.01%, 4.99±0.01%, 1.33±0.01 kg, and 1.26±0.01 kg,
respectively. LogSCC, MY, FC, SNF, PC, LC, FY, and PY were significantly affected by the parity, lactation stage,
and sampling season (P<0.05). Both milk yield and its composition in late lactation were negatively affected by high
SCC compared to early and mid-lactation. MY, SNF, PC, LC, FY, and PY were determined to be the highest in cows
with SCC<100x103
cells/mL, and the lowest in cows with SCC>200x103
cells/mL. Consequently, it may be that milk
loss related to an increase in SCC was, consequently, highest toward the end of lactation. As a result, we suggest that
prevalence measures should focus on reducing the incidence of SCC toward the end of lactation in Holstein cows.