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Milking Interval


Cows walking to the barn.

For 2X/day milking of dairy cattle, the optimum interval is 12 hr; milk accumulation has not significantly lowered the milk secretion rate, but by ~14 hr there is a decline in secretion rate. Compared with a 12 and 12 hr milking interval in a 24 hr period, 9 and15 hr interval results in 1.8% less milk yield, while a 8 and 16 hr interval results in 3.4% less milk.

Image of milking machine on a cow.

In early 1996, the UI Dairy Research Facility switched from milking at approximately a 9 - 15 hour intervals per day to approximately a 12 - 12 hour intervals. The change in relative milk yield in the AM and PM milkings is illustrated by the milk production of this cow, #6036. Because the increase in milk production is small and probably only seen when considering a large number of cows, there is no observable increase in total daily milk yield for 6036 during the period shown here.

Graph of milk yield of a cow at different milking intervals.

Secretion rate in higher producing cows is less affected by long milking intervals (such as 3 consecutive 16 or 20 hr intervals) than the secretion rate in lower producing cows.

Milk composition is different a various intervals after the last milking: (see Fernando and Sphar, 1983, J. Dairy Sci. 66:1155)

  • Na, Cl, and K concentrations and somatic cell count are all high at 3 hr then decline by 9 hr, then increase thereafter.
  • Lactose % is the reverse pattern, highest at 9 hr.
  • Fat % is high at 4 hr then declines
  • Solids-not-fat stays constant (protein, lactose, ash)

(see also Elliot et al., 1960, J. Dairy Res. 27:293 and Wheelock et al., 1966, J. Dairy Res. 33:161)

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