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Milking Frequency


Cows walking to the barn.

Frequency of Nursing or Milking

The frequency at which milk is removed from the mammary gland by the suckling offspring varies substantially among species. For example:

Nursing frequency may be:



kangaroo (joey)

or at intervals of:

.5 hr

whale, dolphin

1 hr


4-6 hr




1X/2 days

tree shrew


Northern fur seal

Milking Frequency in Dairy Cattle

In the case of dairy cattle, management considerations determine how often cows are milked each day. In most dairy cattle management schemes, cows are milked twice daily or three times daily. Cows in milking parlor.
In the case of robotic milking systems (mostly in Europe, but a few currently are in use in North America) where the cows are free to enter the robotic milker as often as they want, typically cows will enter 4 or less times per day. Little additional benefit is attained if they are milked more than 4 times per day.
Example of robotic milking machine.
Example of robotic milking machine.
This is one model of a robotic milking machine that has not been fully set-up. Cows would enter the gates shown on this side of the machine. Cows are milked by the machine shown at the bottom of the image. Controls for the milking machine are on this side of the robotic machine.

Below are summarized some of the original observations on milking frequency in dairy cattle and how those frequencies affect milk yeild.

A. 3 times/day vs. 2 times/day milking. In dairy cattle, milking 3X/day results in increased milk yield, although the observed increase is variable. Generally 3X/day milking increases milk production by up to 25%. But, ~2/3 of this increase is due to better feeding and management and ~1/3 is due to decreased udder pressure. 3X/day milking must be accompanied by a compensatory feeding program; if not, then yield from the continued 3X/d milking will decline back to that from 2X/d. Three times per day milking is more beneficial in late lactation, for example during the first 4 mos. of lactation 3X/day milking increases yield 7-12% over 2X/d. In contrast, during later lactation 3X/day milking increases yield 16-90% over 2X/d. Both first lactation and older cows show increased yield in 3X/day vs. 2X/day milking.

Mammary DNA , RNA and activities of key mammary enzymes are increased in 3x/day milking, vs. 2x/day milking. (see Wilde et al., 1987, J. Anim. Sci. 64:533.)

In switching from 2X/day to 3X/day milking, the cow's response is thought to occur in stages with each stage reflecting a different mechanism (see Table and discussion below).

Sequential Response to Thrice-Daily Milking






(hours to days)

removal of chemical feedback inhibitor

increased milk secretion


Short Term
(days to weeks)

stimulation of cell differentiation

increased milk secretion


Long Term
(weeks to months)

stimulation of cell proliferation

increased milk secretion


Evidence for stage 1: 3X/day milking of one gland produces a unilateral response (see Henderson et al., 1983, Quart. J. Exper. Physiol. 68:645) due to milk removal, not due to decreased physical distention (see Henderson and Peaker, 1984, J. Physiology 351:39).

Evidence for stage 2: There is greater activity of several key enzymes occurs in 3X/day milking (see Wilde et al., 1987, J. Anim. Sci. 64:533).

Evidence for stage 3: There is greater number of cells in the 3X/day milked glands (see Wilde et al., 1987, J. Anim. Sci. 64:533).

Milking 3x/day requires 50% more labor than 2x/day milking. For an economic evaluation of 3X/day vs. 2X/day milking see Culotta and Schmidt, 1988, J. Dairy Sci. 71:1960. The incidence of mastitis and the reproductive performance are not altered by 3X/d milking.

For other references on 3X/day milking vs. 2X/day milking see Pearson et al., 1979, J. Dairy Sci. 62:1941; Waterman et al., 1983, J. Dairy Sci. 66:253; DePeters et al., 1985, J. Dairy Sci. 68:123; Amos et al., 1985, J. Dairy Sci. 68:732; Gisi et al., 1986, J. Dairy Sci. 69:863; Allen et al., 1986, J. Dairy Sci. 69:1441; Wilde et al., 1987, J. Anim. Sci. 64:533.

B. Milking udder halves. Milking one udder half 3X/day gives 16-32% more milk than the udder half milked only 2X/day, even though the halves are exposed to the same systemic stimulation.

Also, milking 2 quarters of cows 4X/day resulted in ~10% increase in milk yield compared to the quarters milked 2X/day (see Hillerton et al., 1990 J. Dairy Res. 57:285). NOTE: In this study, the right rear and left fore quarters were milked 4X/day and the right fore and left rear quarters were milked 2X/day. Remember that the blood flow to one side of the udder serves both front and rear quarters but there is little crossover from left to right. So, this study's results also suggest that the effects are local (within an individual quarter), because the blood flow and systemic hormone concentrations would be the same to both quarters on one side.

C. 4x/day milking. Milking 4X/day results in 5-10% more yield than 3x/day. But is it economical where labor costs are doubled caompared with 2X/day?

D. BST administration to goats milked 3X/day. This resulted in greater milk yield than either in goats receiving BST and milked 2X/day or in goats receiving no BST and milked 3X/day. So, the effects of 3X/day milking and BST apparently are additive.

E. Massaging udders between milkings. This can cause an increase of 1-1.5% in milk yield, although this is probably not statistically significant.

F. Milking less than 2X/day. Milking 3X in 2 days (skipping 1 out of every 4 milkings) resulted in decreased milk yields of 18% when started in week 4 of lactation and a decrease of 11% when started in week 20 (see Eldridge and Clark, 1978, J. Dairy Res. 45:509).

  • 1X/day milking during late lactation results in 35% less milk yield than 2X/day during that period and 12% less milk for the entire lactation. The average length of lactation was reduced by 12 days.
  • 1X/day milking for a complete lactation reduces milk yield by 50% in first calf heifers and reduces milk yield by 40% in older cows.
  • Milking 13X/week vs 14X/week (skipping 1 milking per week; that's 7% fewer milkings per week) reduces milk yield by 5-11% (see Radcliffe et al., 1973, J. Dairy Res. 40:247).
  • Eliminating 2 consecutive milkings/week reduces milk yield by 14% (see Radcliffe et al., 1973, J. Dairy Res. 40:247).

So, while milking frequency can have a significant impact on milk yield in cattle when viewed from the producer's viewpoint, the fact remains that the gland is highly resilient and continues lactating successfully with biologically minor decreases in milk yield even under conditions radically different from modern dairy management practices.

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