Relationship Between Days Open and Cumulative Milk Yield at Various Intervals from Parturition for High and Low Producing Cows

摘要: Abstract Holstein lactation records from New York Dairy Records Processing Laboratory were used to estimate relationships between days open and cumulative milk yield at intervals parturition the effect of number, season freshening, production on these relationships. The relationship with total in also was estimated. Quadratic regression equations that relate 210, 240, 270, 300, 330, 360 number estimated for cows high low yields first, second, third later freshening three seasons. Milk early classify classes production. association less within a class than across all ignored. change 305 associated greater older first but not different producing lactation. This indicates correcting 305-day standard should be additive. Quantities required correct 100 calculated.