Effects of Season and Parity on Milk Production and Milk Composition of Holstein Cows

This study aimed to investigate the effects of seasonal change and parity on milk production and milk composition of Taiwan Holstein Cows. The 171 complete lactation records from 68 Holstein cows, with parity 1, 2, 3, and more than 4 were used in this experiment. Data were grouped into different lactation periods and seasonal CC, CH, HH, and HC (C: Cool, H: Hot). The cool season is from November to April, while the hot season is from May to October. Variables observed were 305-2X-ME, daily milk yield (MY), fat %, protein %, lactose %, total solid %, somatic cell count (SCC), and somatic cell score (SCS). Results showed that season was not significantly associated with 305-2X-ME, lactose %, SCC, and SCS. However, the season had a significant effect (P<0.01) on daily milk yield, protein %, total solid% and tend to be associated (P<0.1) with fat%. The highest milk yield was observed at CH, CC for fat%, lactose% and total solid%, while HH was for protein%. In this study, parity did not significantly affect 305-2X-ME, lactose%, and total solid%. However, it showed significant affect (P< 0.01) in daily milk yield, (P<0.05) in protein and SCC.