Factors affecting daily milk yield, fat and protein percentage, and somatic cell count in primiparous Holstein cows

The objective of this study was to determine effective factors on the variation of daily milk yield (DMY), fat (F%) and protein percentage (P%), and somatic cell count (SCC) in Holstein cows. A total of 278 primiparous cows were examined by four parameters in four calving seasons (CS), three years and six test days (TD) post-calving. While SCC and fat values were affected by CS (P<0.05), no significant difference was found among DMY and P% by CS. Both year and TD were not effective on SCC, but significant differences (P<0.05) were determined among DMY, F% and P% by two factors. Correlation of P% with SCC and F% was estimated to be positive (P<0.01; r=0.168 and r=0.457, respectively), and correlation of DMY with fat and protein was determined as negative (P<0.01; r= -0.363 and r= -0.335, respectively). The study confirmed that multiple milk parameter factors are highly important to obtain more quality and quantity milk from primiparous dairy cows.