Effects of Somatic Cell Count and Various Environmental Factors onMilk Yield and Foremilk Constituents of Red-Holstein Cows

In this study, the effects of somatic cell count (SCC) and various environmental factors on milk yield and foremilkconstituents in Red-Holstein (RH) cows raised under Mediterranean climatic conditions in Aydın Province in Turkey were determined. A total of 891 foremilk samples collected from 129 cows during morning and evening milkings in winter and summer seasons between 2009 and 2012 were analysed for protein content (PC), lactose content (LC), non- fat dry matter content (NFDMC), and SCC. SCC data were split into 6 groups ( 100,000 cells mL^-1; 100,000-199,999 cells mL^-1; 200,000-299,999 cells mL^-1; 300,000-399,999 cells mL^-1; 400,000-750,000 cells mL^-1; and 750,000 cells mL^-1) before statistical analysis. LS MEANS of sampling time milk yield (STMY), PC, LC, NFDMC, and Log SCC for winter and summer seasons were 11.27±0.253 kg and 10.59±0.226 kg (P 0.05), 3.24±0.024% and 3.04±0.021% (P 0.01), 4.44±0.028% and 4.48±0.025% (P 0.05), 8.68±0.045% and 8.50±0.040% (P 0.01), and 5.051±0.0508(112,461 cells mL^-1) and 4.914±0.0428 (82,035 cells mL^-1) (P 0.05), respectively. Compared to the first SCC group, STMY, LC, and NFDMC decreased to 1.1 kg (9.4%), 6.4%, and 3.8% in the fifth group and 1.49 kg (12.7%), 11.3%, and 6.3% in the sixth group, respectively (P 0.05). In conclusion, LC could be used as a mastitis marker due to a distinct decrease in LC as SCC increases. Additionally, due to significant reductions in the STMY, PC, and NFDMC in the summer season, some precautions are required to prevent possible heat stress in this herd and the herds managed in theregions with hot summer months.