Effect of Somatic Cell Count on Fertility and Milk Yield Traits During Different Lactation Periods in Holstein Cows
2025
Orhan Ermetin | İbrahim Cihangir Okuyucu | Ertuğrul Kul
The aim of this study was to evaluate the effect of somatic cell count (SCC) variation on fertility [days open (DO), number of inseminations per pregnancy (NIPP), calving interval (CI) and gestation length (GL)] and milk yield traits [daily milk yield (dMY), lactation length (LL), lactation milk yield (LMY) and 305-days milk yield (305-dMY)] during early (< 100 d), mid (100-200 d) and late lactation (> 200 d). This study was conducted with primiparous and multiparous Holstein cows at a commercial farm having an approximate herd size of 260 heads in Kırşehir, Türkiye. A total of 107 Holstein dairy cows on the farm were selected. Milk samples were collected once a month during morning milking between 30 and 240±15 d of lactation. The somatic cell counter (DCC, DeLaval, Tumba, Sweden) was used to assess SCC (cells/ml). SCC levels were categorized into three groups (< 100 × 10³ cells/mL, 100-200 × 10³ cells/mL and > 200 × 10³ cells/mL). Cows were divided into three groups according to parity: Cows with parity 1 (first group; n = 49), cows with parity 2 (second group; n = 30) and cows with parity 3 ≤ (third group; n = 28). Parity did not influence fertility traits (P>0.05). Parity significantly affected dMY and 305-dMY, but not LL or LMY. The study found that cows with SCC < 100 × 10³ cells/mL had lower DO and CI values compared to cows with SCC 100-200 × 10³ cells/mL and > 200 × 10³ cells/mL during mid-lactation, although no statistical differences were observed in the NIPP, GL, dMY, LL, LMY and 305-dMY values. A positive correlation was observed between SCC groups and DO during mid-lactation. These findings suggest that SCC can be used as an indicator in indirect selection programs to achieve shorter DO and CI in Holstein cows.
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