Relationship Between Milking Intervals and Individual Milk Weights

Abstract

Starting and finishing times of milkings were used to analyze the relationship between milking interval and individual milk weights of 184,521 test-day records on 19,-905 cows of five dairy breeds in 555 herds. Morning milk production exceeded evening milk production by approximately .10kg, with equal intervals between milking for an average of 150 days in milk. The difference between morning and evening milk production was primarily a function of the milking interval and the number of days in milk lactation-to-date. As the number of days in milk increased, there was a decrease in the difference between morning and evening production of about .35kg for each 100 days in milk. Morning milk production exceeded evening milk production approximately 1.2kg for every hour increase in the evening-morning interval beyond 12 hours. Wide deviations from a 12-hour milking interval may produce biased and misleading estimates of the producing ability of cows tested under the alternate morning-evening production testing scheme, if adjustments are not made for unequal milking intervals.