Effect of strain of Holstein–Friesian and feed system on udder health and milking characteristics

The objective of this study was to quantify the effect of three alternative strains of Holstein–Friesian dairy cows, parity and feed system on udder health and milk flow characteristics. The three strains of Holstein–Friesian compared were, high production North American (HP), high durability North American (HD) and New Zealand (NZ). The three feed systems compared were, a high grass allowance feed system typical of spring calving herds in Ireland (MP), a higher concentrate system (HC), and a higher stocking rate system (HS). The data comprised up to 584 lactations from 240 cows across 5 years, from one research herd. The NZ stain had significantly higher average lactation somatic cell count (87,553 cells/ml) than the HP (60,475 cells/ml) or HD strains (59,278 cells/ml). Nonetheless, differences between strains were not biologically important. No significant strain effect on incidence of clinical mastitis was observed; average lactation incidence of clinical mastitis was 26%. The NZ strain had the highest peak milk flow (5.45 kg/min) and the shortest average milking duration (6.60 log sec/day). Feed system had no significant effect on udder health while significant feed system effects were observed on milking characteristics including average milk flow and average and maximum milking duration. This study indicates significant variation in somatic cell count and milking characteristics between strains, which when coupled with their economic importance, suggest the necessity to include these in overall breeding objectives.