________________________________________________________________________________________ KUl, E., A. ŞAHİn, S. ATASEvEr, E. UğUrlUTEpE, M. SoydAnEr: The effects of somatic cell count on milk yield and milk composition in Holstein cows. vet. arhiv 89, 143-154, 2019.
ABSTrACTThis study was conducted to assess the impact of somatic cell count (SCC) on the test day milk yield (TDMY) and milk composition parameters (fat, solids-not-fat, protein and lactose) of Holstein cows raised in the Kırşehir province of Turkey. A total of 1194 raw milk samples were collected from 195 Holstein cows at different stages of lactation (from 1 to 7), parities (from 1 to 3) and calving seasons (autumn, winter, spring and summer). Also, TDMY and milk composition traits were tested by SCC in four groups (<100×10 3 , 100-200×10 3 , 201-500×10 3 and >500×10 3 cells/mL). For statistical evaluation, SCC data were converted to log 10 base. The overall means of log 10 SCC, TDMY, fat, solids-not-fat (SNF), protein and lactose were determined as 4.95 ± 0.016, 33.36 ± 0.232 kg/day, 3.39 ± 0.021%, 9.04 ± 0.013%, 3.32 ± 0.005% and 4.92 ± 0.007%, respectively. Log 10 SCC, TDMY, fat, SNF, protein and lactose were significantly affected by the stage of lactation, parity and calving seasons (P<0.05). An increase in the SCC was accompanied by a decrease in the milk yield as well as its content (P<0.05). Cows' milk with high SCC (>201×10 3 cells/mL) had a lower TDMY than milk with lower SCC (<100×10 3 and 100-200 cells/mL). However, the lowest fat, SNF, protein and lactose were determined in milk with SCC >500×10 3 cells/mL. It was concluded that SCC in milk should not exceed 500×10 3 cells/mL for Holstein cows, suggesting that monthly control of SCC may be effective for improving milk production and milk quality in Holstein cows.
