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ABSTRACT

THE EFFECTS OF THREE PULSATION RATIOS
ON MILK FLOW RATES

by Eldon LeRoy Spicer

To compare the effects of three different pulsation
ratios on the average and peak milk flow rates is the object
of this study. Thirty-four cows in different stages of lac-
tation and representing three of the dairy breeds, 2h Hol-
stein, 6 Brown Swiss, and S Jerseys, were used in this
experiment.

Three pulsation ratios (the milking to rest ratio)
were used in this study with two of these, a 50:50 ratio and
a éu:36 ratio, applied to the entire udder while the third
was a variable ratio using a 6h:36R (R indicates rear) ratio
for the rear half, and a 36:6hF (F indicates front) ratio
for the front half. These pulsation ratios were obtained by
the use of a timer-converter and by modifying the standard
De Laval milker claw and pulsator.

The milk flow data that were recorded in graphic form
on a tape by the recording Milk-O-Meter were studied and con-
verted into milk flow rates. Samples of milk were taken from
each cow at each milking to determine the effect of each
pulsation ratio on udder irritation which was determined by
the use of the Milk Quality Test. The irritation study was

a separate project being carried on simultaneously by another

Eldon LeRoy Spicer

investigator. Slightly higher average and peak flow rates
were obtained when the cows were milked with the 6h:36
pulsation ratio than when milked with the 50:50 or 6h:36R -
36:6uF ratios. The 6h:36R - 36:6AF pulsation ratio gave the
lowest average flow rate. With the Brown Swiss and the
Jersey breeds the éu:36R - 36:6MF gave a slightly higher
peak flow rate than that obtained with the 50:50 pulsation
ratio.

Analysis of variance showed a highly significant dif-
ference between the breeds in both average and peak flow
rates, but no significant difference between the ratios.

The results of the Milk Quality Test indicated that
the 6h:36 pulsation ratio caused the least irritation, while

the 50:50 ratio caused the greatest irritation.

THE EFFECTS OF THREE PULSATION RATIOS

ON MILK FLOW RATES

By

ELDON LEROY SPICER

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Dairy

1962

ACKNOWLEDGEMENTS

The author wishes to express his sincere appreciation
to Professor W. W. Snyder for his very helpful direction and
assistance throughout this study, to Dr. E. Weaver and Alma
M. Campbell for reading the manuscript, to Dr. W. F. Buchele
for his technical advice in setting up the pulsation ratios,
to R. Thomas for his assistance in handling the statistical
data for the study, and to M. A. Wilson for his assistance
in collecting the data.

The author is indebted to Dr. C. A. Lassiter, chairman
of the Department of Dairy, for making facilities and animals
available, and to D. V. Armstrong, herdsman, and his assist-
ants in the barn who aided in the collection of the data.
Also the author is indebted to C. M. Crosby and the De Laval
Company for supplying some of the equipment needed for this
study.

The author appreciated the financial support provided
by Emmanuel Missionary College which made his study at
Michigan State University possible.

Finally, the author is deeply grateful to his wife,
Anna, for her encouragement and assistance in the prepara-

tion of this manuscript.

ii

TABLE OF CONTENTS

Page

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1
REVIEW OF LITERATURE . . . . . . . . . . . . . . . . .
History of the Milking Machine. . . . . . . . .
Functions of the Milking Machine. . . . . . . .

The Vacuum Pump . . . .

The Teat Cup Assembly .

The Pulsator. . . . .
The Vacuum Regulator.

Weighing Devices. . . . . . . . . . . . . . . .
Factors Affecting Milk Flow Rates . . . . . . .

Day-to-Day Variation. . . . . . .
A. M. and P.M. Milking . . . . . .
Stage of Lactation. . . . . .
Variation Among Individual Cows .
Variation Between Breeds. . . . .
Inheritance . . . . . . . . .
Variation Between Quarters. .
Milking Rate and Yield. . . .
The Sphincter Muscle. . . . . .
Vacuum Levels and Pulsation Rates . .

S

o o o o

Pulsation Ratios and Vacuum Levels.
Effects of Stimulation Before Milkin

5&3

EXPERIMENTAL PROCEDURE . . . . . . . . . . . . . . . . 21
Pulsation Ratios. . . . . . . . . . . . . . . . 22
The Recording Milk-O-Meter. . . . . . . . . . . 31
Procedure for Collecting Data . . . . . . . . . 31
Milking Rates . . . . . . . . . . . . . . . . . 33
The Milk Quality Test . . . . . . . . . . . . . 35
RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . 38

Average Flow Rate . . . . . . . . . . . . . . . RO

iii

TABLE OF

Peak Flow Rate.

Machine Time.

Udder Irritation.

8111qu HY. O O O O 0
CONCLUSIONS. . . .
LITERATURE CITED .

CONTENTS--Continued

iv

Page
R1
15
LL?
1+9
50
51

TABLE

II

III

IV

VI

LIST OF TABLES

Page

The Order in.Which Data Were Collected for
Three Pulsation Ratios. . . . . . . . . . . . 32

Average Flow Rates and Peak Flow Rates Ob-
tained From Three Pulsation Ratios. . . . . . 38

The Mean Differences in Average Flow Rate
and Peak Flow Rate For Three Dairy Breeds . . Al

The Average Milk Yield Per Milking and
Machine Time As Obtained From Three Pulsa-
tion Ratios O O O 0 O O O O O O I O O O O O O [4.3

The Average Milk Yield and Machine Time By
Breed As Obtained From Three Pulsation
Ratios. O O 0 O O O O O O O O O O O O O O O 0 LL;

The High, Low, and Average Machine Time
for the Holstein, Brown Swiss and Jersey
Breeds. O O O O O O O O 0 O O 0 O O O 0 0 O O [4.6

LIST OF FIGURES

FIGURE

1 The modified De Laval timer-converter used
for obtaining pulsation ratios. . . . . . .

2 The converted standard De Laval milker claw
used to obtain the euz3e pulsation ratio. .

3 The converted standard De Laval pulsator
used to obtain the 6h:36 pulsation ratio. .

h A device used to by-pass the air ports of

the standard De Laval milker claw . . . . .

5 A device attached to the standard De Laval
milker claw, used to by—pass the air ports.

6 A graphic recording tape used with the re-
cording Iqilk-O-Metero o o o o o o o o o o o

7 A device used to facilitate the reading of
the graphic tapes . . . . . . . . . . . . .

vi

INTRODUCTION

Now that the dairyman has firmly established the
milking machine on the modern dairy farm much study is
being done to make this piece of equipment even more
efficient for removing milk from the udder at a faster
rate and with the least possible irritation.

Various methods have been employed to speed up the
rate of milk flow from the udder. Several investigators
have increased the vacuum level to overcome normal resist-
ance to the teat sphincter, others have combined higher
vacuum levels and faster pulsation rates, and some have
given study to the effect of pulsation ratios on milk flow
rates.

The object of this investigation was to ascertain the
effect of three different pulsation ratios upon the rate of

milk removal from the udder.

REV IEW OF L ITERATURE

The literature will be reviewed with respect to the
effects of various factors on milk flow rates during milking.
These factors include day to day variation, a.m. and p.m.
milking, stage of lactation, variation among individual cows,
variation between breeds, inheritance, variation between
quarters, milking rates and yields, the sphincter muscle,
vacuum levels and pulsation rates, pulsation ratios and

vacuum levels, and stimulation before milking.

History of the Milkigg Machine

 

Erf (17) described many types of pressure devices and
milking tubes designed to remove milk from the udder. He
stated that American inventors attempted to perfect milking
machines as early as 1819. No good descriptions or illus-
trations were made of these machines. One of the simplest
schemes for milking, aside from hand milking, was the use of
straws inserted into the cow's teat, a procedure which al-
lowed the milk to run from the milk cistern. W011 and
-Humphrey (R6) reported that the first American patent on a
continuous suction machine was obtained in 1860.

Mattick gt_gl. (26) report that in 1836 Blurton, an
Englishman, patented a cannula machine in which the pail was
suspended from the cow. They also state that two British

inventors, Hodges and Brockenden, in 1851, were probably the
2

first to use vacuum for removing milk from the udder, and.

that Clovin of the United States extended the idea in 1860
to include a form of teat-cup. In 1895 and 1896 Shields of
Glasgow took out patents for a device which he called a
pulsator. His idea was to relieve the teats of constant
vacuum. In 1897 Lawrence and Kennedy developed a milking
machine in which Shields' principle of a pulsating vacuum
was used, with a small motor situated on the pail lid to
obtain this vacuum.

In 1902 Hulbert and Park of New York patented a teat-
cup with an inflatable lining divided into three sections.
Mattick 32 El! (26) also reported that Gillies of Australia,
in 1903, invented a double-chambered teat-cup to operate on
vacuum alone and applied this teat-cup to the Lawrence-
Kennedy machine which had been imported from Great Britain.
The pulsator was now used to apply a squeeze to the teat by
varying the pressure in the annular chamber instead of di-
rectly interrupting the vacuum applied to the teat. With
this combination the Lawrence-Kennedy-Gillies milking machine
was develOped, the first to embody all the principles of

machine milking as we know it today.

Functions of the Milking Machine

Mattick and others (26) state that the principle used
by all modern milking machines to draw milk from the udder of

a cow is, with few exceptions, basically the same as that

established by the Lawrence—Kennedy—Gillies milker of 1903.
This involves the application of a constant vacuum to the
end of the teat to draw the milk out and convey it to a
separate container, tOgether with a periodic squeeze applied
externally to the teat in order to prevent congestion at the
end of the teat. This is brought about by the principle of
pressure differentials, the air pressure at the end of the
teat being reduced so that the higher milk pressure within
the teat will overcome the effects of the sphincter muscle
and thus cause the milk to flow out.

The milking machine in general is comprised of four
main parts consisting of the vacuum pump, the teat cup as-
sembly, the pulsator, and a vacuum regulator. In addition,
the vacuum line, the milk conveying system, and the milk pail
could be included as part of some specific milking system,

but their functions need not be discussed in this thesis.

The Vacuum Pump

As described by Mattick and co—workers (26) and
Noorlander (28), the purpose of the vacuum pump is to exhaust
air continuously from the milking system in order to maintain
the necessary vacuum level at the end of the teat for milk
withdrawal, to operate the pulsator, and at the same time to
maintain a constant level of vacuum throughout the system
during the entire milking Operation. To Operate efficiently
the pump must have reserve capacity.

Mattick £2.3l: (26) and Noorlander (28) report that

5

the degree of vacuum in a milking system during operation is
expressed as inches of mercury measured as a differential
from atmospheric pressure and indicated by a conventional
vacuum gauge. This differential is commonly referred to as

the vacuum level.

The Teat Cup Assembly

Espe and Cannon (l8) and Mattick and co-authors (26)
described the teat cup assembly as a cylindrical metal shell,
containing a rubber liner shaped so that it makes an air-
tight seal with the shell at the tOp and bottom, leaving a
chamber between the shell wall and liner. The liner is open
at the tOp into which the teat is inserted, and the bottom is
attached to the milk receiver or teat cup claw. During the
milking there is constant vacuum at the teat end of the

liner.

The Pulsator

Mattick gt El. (26) and Noorlander (28, 29) have
described the functions of the pulsator in detail. These
authors state that the pulsator admits air into the chamber
between the shell of the teat cup and the liner during one
phase of pulsation and then permits the vacuum pump to re-
move the air from this space during the next phase of the
pulsation. This causes the liner to Open when vacuum is ap-

plied and then to collapse when air is admitted, with the

6
open phase being the milking part of the cycle and the col-
lapsed phase being the resting part.

The purpose of this air rushing in several times a
minute from the pulsator is to permit the liner to close
with enough force and duration to reduce the vacuum on the
outer teat surface, and to permit the liner to massage the
teat. Constant vacuum without pulsation causes congestion
at the end of the teat, but this massaging action maintains
a reasonably normal blood circulation in the teat. The fre-
quency of these cycles or pulsation rates depends on the
make of the milking machine, and varies from LO to 120 pulsa-
tions per minute. Most milking machine manufacturers recom-
mend a specific pulsation rate for their machine.

The speed at which milk is removed from the teat de-
pends upon the time ratio between the open and closed phases
of the complete pulsation cycle. The ratio of the times
occupied by the two phases is called "pulsation ratio" or
"milking ratio". This ratio may vary from 50:50 to about
75:25, which means that the teat cup liner is in the milking
phase 50 or 75 percent of the cycle. Most pulsators in this
country are designed for ratios from 50:50 to 60:h0.

Several authorities, Mattick §t_§l, (26) and Noor-
lander (28), agree that a milking ratio with a wide Open time
of over 50 percent usually results in faster milking, but it

may not provide enough closed time to permit prOper teat

massage.

The Vacuum Regulator

The function of the vacuum regulator as described by
Mattick gt_§13 (26) is to Open an air inlet valve in the
vacuum line and allow air to enter the line when the vacuum
exceeds the desired level. When the Operation of the milking
machine permits air to enter the system, the vacuum decreases,
the valve of the vacuum regulator closes, excluding the inlet
of additional air until the desired vacuum level is obtained.
The regulator can not prevent changes of vacuum, it can only
operate to prevent a vacuum above a predetermined level. If
an inadequate pump is used or if the vacuum line has too many
air leaks, the regulator is not capable of making up lost
vacuum; hence the system will not be Operating efficiently.
To obtain the best results from the regulator, a pump with
sufficient reserve capacity and of adequate size to handle a
given number of milking units, must be used. A vacuum line

free of air leaks is also essential.

Weighing Devices

 

One of the simplest methods of indicating milk flow
rates is the use of the stop watch for recording the length
of time the teat cups remain on the cow during milking. This
method is limited, because the moment when the machine is re-
moved from the cow will not often coincide with the end of
milk flow. Where more accurate records are needed it is

necessary to measure the rate at which milk is removed from

the cow throughout the whole course of the milking period.
This is done in a number of ways.

As reported by Dodd SE 31: (12), Mattick and others
(26), and Smith and Petersen (35), one method is to suspend
a milking machine pail from a scale and take readings at
frequent intervals--10, 15, or 30 seconds. This method
probably has been the most used in the past.

The individual quarter milking machine has been used
as described by Baxter gt_gl, (3), Hall (22), and Matthews
gt_§l. (27). This is a machine to deliver the milk from dif-
ferent quarters through separate tubes to four compartments
in a bucket or to four separate cylinders which are graduated
in pound and one-tenth pound divisions.

More recently the use of automatic recording equipment
has been reported by Baxter (3), Whittlestone and Phillips
(R3), and Hupp (25). One advantage of this procedure is that
continuous recordings can be made without having strange ob-
jects near the cows during milking. Ace §t_gl. (l), Gaines
(l9), and Whittlestone (kl) have described other devices for

recording milk flow rates.

Factors Affecting Milk Flow Rates

Day-tO-Day Variation

Dodd (1h) gathered data on day-to-day variation in
milk flow rates from lhl cows, with 326 records. The results

indicated that day-to-day variations in the true measure of

milking rate for a particular cow are relatively small as
long as the milking routine is constant and correction is

made for lactation trends.

A.M. and P.M. Milking

After studying the records of six cows for six consecu-
tive days, Dodd (1R) found some variation between a.m. and
p.m. milk flow rates. He states that while the rates in the
mid-milking rate, peak flow, and machine rate were greater
at the morning milking, the total time is longer because of
the much higher yield.

Hupp (25) found no significant differences in the rate
of flow when 12 hours intervened between milkings, or when
11 or 13 hours intervened between milkings.

Matthews §t_gl, (27) and Dodd and Foot (11) showed
that if the differences in interval between milkings are
great, such as 9- and 15-hour intervals, or 8 and 16 hours,
differences in the rate of flow between the two milkings

occur, the greater flow coming from the longer interval.

Stage of Lactation

In collecting data from R32 milkings of R8 cows during
the early, middle, and late stages of lactation, Beck gt_gl.
(R) found that both milk flow rate and the total time required
to milk declined during the lactation period. Dodd's work

(1R) also showed that the milking rate declines as lactation

10
advances, and that the decline is greater for fast milking
cows.

Hupp (2R) found that cows in their first lactation
milked at a significantly faster rate as the lactation pro-
gressed. The change in rate of flow during the lactation of
cows in their second or subsequent lactations was not sig-
nificant.

In two consecutive lactations of R2 cows, Holthoff
(23) reported that there was no increase in the rate of milk
flow between the first and second lactation.

Work done by Comberg and Zschommler (10) showed that
milk flow rate was not affected by pregnancy or length of

lactation.

Variation Among Individual Cows

Perhaps the most clear-cut finding has been that the
rates of milking of individual cows show very wide differ-
ences, even in self-contained herds with cows milked in the
same manner.

Some work done in England as reported by Mattick gt_gl.
(26) showed wide differences in peak flow rates of individual
cows at the same stage of lactation, giving similar milk
yields.

Elting's and LaMaster's work (16) showed that 7.0 per-
cent of all cows required less than R.0 minutes, 81 percent
required R.0 to 6.5 minutes, and 12 percent required over 6.5

minutes for the complete milking time. The minimum time

11
required for any cow was 3 minutes and 22 seconds, while the
maximum time was 8 minutes and 17 seconds.

Mattick and co-authors (26) reported on some data that
were collected from 326 lactation records which illustrated
that at the peak of lactation when the duration of milking
is at its maximum, most cows take from R.0 to 8.0 minutes to
milk. These cows were milked with lR inches of vacuum, a
pulsation rate of 50 cycles per minute, and a pulsation ratio
of 50:50.

Petersen (30) and Beck (R) also found great variation
in the rate of milking between cows. As reported by Hupp
(25), Thoele found the differences in the rate of milking

between cows to be significant at the one percent level.

Variation Between Breeds

Beck and his co-workers (R) conducted milk flow studies
to determine the variation between breeds on the average rate
of flow, maximum rate of flow, percent of yield obtained at
2.0 minutes, and machine time. They used a standard upright
pail—type milking machine with 15 inches of vacuum and R8
pulsations per minute. One hundred and two cows of the Ayr-
shire, Holstein, Guernsey, and Jersey breeds were used. Vari-
ations in machine time ranged from 2.0 to 7.0 minutes, with
an average of 3.5 minutes per cow. Seventybsix percent of the
cows milked out in R.0 minutes or less, and 39 percent of the
cows milked out in 3.0 minutes or less.

The t-test was used to determine the significance of

l2

differences between any two breeds for a given measurement.
In average rate of flow the Holstein breed differed signifi-
cantly from the other three breeds, exceeding the Jerseys
about 27 percent, the Ayrshire about 35 percent, and the
Guernseys about 65 percent. In maximum rate the Jerseys
exceeded the Guernseys about 63 percent which was highly sig-
nificant. The differences between the Jersey and Ayrshire
breeds and between the Ayrshire and Guernsey breeds were not
significant according to the t-test. In machine time the
Holsteins and Jerseys were similar, with both breeds milking
out significantly faster than the Ayrshires and Guernseys in
that order. The breeds ranked in machine time, from fastest
to slowest, as follows: Jersey, Holstein, Ayrshire, and
Guernsey.

Statistically significant variations between the Brown
Swiss, Holstein, Guernsey, and Jersey breeds were found in
rate of milking by Stewart 33 El, (38). Both the rate of
milking and total milking time decreased significantly with

advanced lactation.

Inheritance

There is some indication that milking rate is a her~
itable factor. Beck gt_gl. (R) reported that there were
statistically significant differences in the speed of milking
that could be attributed to the sire within a breed. Dodd
and Foot (13) reported one sire with eight daughters, all of

which were slower milkers than their dams; and another sire

13
with eight daughters whose rate of milking was very similar
to their dams. They also reported significant correlations
of 0.37 on R0 daughter-dam pairs and 0.37 on 35 pairs of
sibs and half-sibs.

Donald (15) reported that heritability of peak flow
rate derived from Observations on paired singleborn cattle
and twins was 85 percent. Repeatability was 0.8 - 0.9.

Other workers, Stewart gt 31. (38) and Matthews 3E.Elf (27),
also presented work which indicates that milking rate is a

heritable factor.

Variation Between Quarters

Matthews §E_gl. (27) found that in many cows there
were wide differences in the performance of the separate
quarters of the udder. They observed 9R cows and found that
R8.9 percent of these cows showed a difference of 20 percent
or more between the quarters with the lowest percentage of
its total yield milked out following the first 2.5 minutes
of milking. In RO.R percent of the cows a difference of 0.6
pounds of milk per minute or more between the quarters with
the highest peak flow rate and the quarters with the lowest
peak flow rate was obtained. Smith and Petersen (35) and
Comberg and Zschommler (10) also reported wide differences in

the performance of separate quarters of the udder.

Milking Rate and Yield

Positive correlations between total milk yield and
milking time (r=O.R7Rt0.0R2), and total milk yield and flow
rate (r=0.7R6tLO25) were reported by Holthoff (23), but the
correlation between flow rate and milking time (r=-0.097)
was not statistically significant.

Clough and Dodd (9) and Sandvick (32) have presented
some evidence which indicated a relationship between milk
yield and milking rate. This gives some strength to the
belief that milk yield is dependent to some degree on the

rate of milk removal from the udder.

The Sphincter Muscle

The sphincter muscles play a large part on the rate at
which a certain amount of milk can pass out of the teat in a
given time as reported by Mattick g3 31, (26), Whittlestone
(R2), Gregoire (21), Smith and Petersen (35), Turner (R0),
Stewart g£_§l. (39), and Gonokhov (20).

Baxter and those working with him (3) conducted a study
in which they milked the two hind quarters of four cows by
teat cup and by teat cannula at three levels of vacuum--10.6,
15.9, and 20.R inches, using the individual, four cylinder
type, quarter milking machine. The cannula was inserted into
the ends of the teat and connected to the lid of one of the
cylinders by the normal milk tube. During the experimental

milkings the cannula was used on one hind quarter, while the

15
other three quarters were milked in the normal way with the
teat-cups. This procedure made possible the study of flow
rates at each level of vacuum through an orifice of a size
determined by the bore of the cannula. When the eight
quarters were milked by the teat-cup the maximum flow rates
were significantly different. When the teat cannulae were
used the eight quarters milked at nearly the same rate, sug-
gesting that the teat orifice is a very important factor in
controlling rate of milking.

The maximum rate of milking by both the teat-cup and
the teat cannula increased with the increase of the level of
vacuum from 11 to 20 inches. The rate of increase was
greater in the teat—cup than in the cannula milking. This
suggests that the teat orifice was stretched Open to a
greater degree at the higher levels of vacuum.

Stewart gt_gl. (39) did some work with slow milking
cows that gave support to Baxter's suggestion that higher

levels of vacuum enlarge the teat orifice.

Vacuum Levels and Pulsation Rates

Smith and Petersen (3R) were the first to demonstrate
that increased milking rate could be obtained with higher
operating vacuums. They compared milk flow rates at 10, 12,
1R, and 16 inches of vacuum, with a pulsation rate of 50
cycles per minute for all observations. The differences of
milk flow rate varied from 0.R3 pounds per 10 seconds for 10

inches of vacuum to 0.8R pounds per 10 seconds for 16 inches

16
of vacuum. These data when treated statistically show that
the differences in milk flow rate between the different
levels of negative pressure were highly significant.

The work of Whittlestone and Verral (R2) did not agree
with Smith's and Petersen's findings. However, a number of
other workers, Stewart §t_§l: (39), Porter gt_g1: (31), and
Bratlie (6), have shown that with higher levels of vacuum
milk is withdrawn from the udder at a faster rate.

Stewart and Schultz (39), working with slow milking
cows, milked with the machine Operated at vacuum levels of
10, 12.5, and 15 inches of vacuum. They found that increasing
the level of vacuum increased the speed of milking, and that
the increase in milk flow rate was greater when they increased
the vacuum from 10 to 12.5 than when they increased it from
12.5 to 15 inches. A standard single-unit, Sterling-type
De Laval milker was used in this study.

As noted by Smith and Petersen (35) the negative pres-
sures developed on the nipple of a calf pail were invariably
greater than the values obtained when the calves sucked cows.
The maximum negative pressure develOped by sucking on the
nipples ranged from 12 to 18 inches of vacuum as compared to
a range of 9 to 16 inches when the calves sucked the cows.
These authors suggested that the calf can develop sufficient
negative pressure to overcome normal resistance of the teat
sphincter. When they put the same calf on a cow known to be
an easy milker and on one known to be a hard milker, they

found that on the easy milker 10 inches of vacuum was needed

17
by the calf to withdraw the milk from the udder, whereas on
the hard milker 16 inches was needed.

It is often believed that fast pulsation speed in-
creases the speed at which cows are milked. This is not the
case unless the pulsation rate is so rapid that the liner
does not fully collapse, and if this condition takes place
damage to the teat is almost certain (26, 28).

Stewart and Schultz (39) used pulsation rates of 20,
50, and 80 per minute and found that in general, increasing
the pulsation rate significantly increased the speed of
milking, but not as much as did increasing the vacuum level.
The effect of increasing pulsation rate was most marked when
increasing it from 20 to 50. No noticeable effect occurred
on increasing the rate from 50 to 80.

Clough at £1. (7) studied the results on milk flow
rates when using three different pulsation rates. They used
rates of 20, 50, and 80 pulsations per minute, with a vacuum
of 15.2 inches and a 50:50 ratio. Their data indicate that
the increase in pulsation rate gave faster milking, and that
all the effects were significant at the five percent level.
They stated that the faster the pulsation the faster will be
the milk-flow at the time of maximum let-down, but it is pos-
sible that it will be less efficient than a slower pulsation
at the end of let-down when the internal pressure has drOpped
and the teats do not fill so readily with milk.

Bratlie gt 31. (5) divided 16 cows into two similar

groups and used a pulsation rate of R0 for a control while

18
pulsation rates of 60 for one trial and 75 for a second trial
were used on the experimental cows. The experimental cows
produced R.8 percent less milk than the control cows, and the
difference was significant. The milking time was slightly
longer for the experimental cows, but the peak flow rate was
similar for both groups. There was some indication of ad-
verse effects on the teats from the higher pulsation rates,
also high cell counts were more frequent in the experimental

group than in the control cows.

Pulsation Ratios and Vacuum Levels

The first experimental work done to observe the effect
of variation in pulsation ratio on milk flow rates was done
by Smith and Petersen (36). They found that widening the
pulsation ratio increased the rate of milk flow, but they
did not consider this increase of any great importance.
Raising the pulsation ratio from that of 50:50 to 60:R0 (60
percent milking) and 75:25 gave a slight increase in milk
flow rate. Widening the milking ratio increased the rate of
milk flow but not in prOportion to the increased time of
vacuum application. The 75:25 ratio had a tendency to in-
crease teat congestion.

A more recent study has been made by the National
Institute for Research in Dairying and reported by Mattick
and others (26). They milked a group of cows at 15 inches
of vacuum with varying pulsation rates and ratios. The

milking rate increased over 30 percent when the pulsation

19
rate was increased from R0 to 160 per minute at a pulsation
ratio of 1:1. With a pulsation rate of R0, the milking rate
was increased by 23 percent when the pulsation ratio was
changed from 1:1 to 2:1, and 3R percent when the pulsation
ratio was changed from 1:1 to 3:1. When the pulsation rate
was set for 160 cycles per minute there was an increase in
milking rate of R0 percent when the pulsation ratio was
changed from 1:1 to 3:1.

Average yield and milking time of a group of cows
milked at 15 inches of vacuum and 60 pulsations per minute
with ratios of R:1 and 1:1 at intervals of 12 and 12 hours
or 1R and 10 hours were compared. With each milking interval
milking time was reduced when the pulsation ratio was changed
from 1:1 to R:1. The milking time of slow-milking cows was
also decreased.

Changing the pulsation rate and widening the ratio
enabled Ardran g£_§l: (2) and Clough and Dodd (8) to increase
the maximum milking rates. Wilson (R5) reported that when
the pulsation ratio was widened from 1:1 to R:1 there was a
greater increase in peak milk flow than that obtained by an

increase of vacuum from 13 to 25 inches.

Effects of Stimulation Before Milking

Higher rates of milk removal were obtained by Smith
and Petersen (37) when cows were stimulated before milkinG.
Hupp (25) reported that the maximum rate of flow was

significantly faster if the teat-cups were put on the teats

20

immediately after preparation.

It has been suggested by Whittlestone (AU) and Turner
(R0) that the reason for some cows being slow milkers was
due to insufficient let-down of milk, but Hupp (25) injected
a group of cows with oxytocin and found that it had no ef-

fect on rate of milk flow with average and fast milking cows.

EXPERIMENTAL PROCEDURE

All the cows that were housed in one of the dairy
barns of Michigan State University were used in this experi—
ment. At the beginning of this study the milking string
consisted of a group of 65 cows in different stages of lac-
tation.

During the experimental period some cows ended their
lactations, others started their lactations, some were culled
from the herd, a few develOped some adverse udder conditions,
and data were not collected from a few cows due to some ir-
regularities in communications. Because of these factors it
was not possible to collect data from 31 cows during the
entire experimental period, and it was deemed necessary to
drOp these from the experiment. This left a total of 3R cows
in the final analysis, consisting of 23 Holstein, 6 Brown
Swiss, and 5 Jerseys.

The cows were milked in tie-stalls by one man Oper-
ating three milker units of a De Laval pipeline milking
system. The man operating the milkers also prepared the
cows before milking. The udders Of the cows were washed
with warm chlorinated water, massaged to facilitate the
prOper let-down, and checked with a strip—cup for mastitis.
In most cases the teat cups were placed on the teats within
two minutes after udder preparation. As far as possible the

cows were milked in regular order.

21

22
In this study the De Laval Magnetic milking machines
were used, with some alterations made in order to obtain the
proper pulsation ratios desired. The milking machines were
Operated with 12.5 inches of vacuum and a pulsation rate of
R8 cycles per minute. The De Laval 05 liners were used

during the entire experiment.

Pulsation Ratios

 

In this experiment the average milk flow rate and the
peak milk flow rate for three different pulsation ratios (the
milking to rest ratios) were studied. With two of these
ratios, a 50:50 ratio and a 6R:36 ratio, the entire udder
was milked with the same ratio. The third ratio was a vari-
able ratio using 6R:36R (R indicates rear) for the rear half
and a 36:6RF (F indicates front) for the front half. Since
on the average 60 percent of the milk is produced by the two
rear quarters and R0 percent by the two front quarters, this
third ratio was used with the hope that greater flow rates
would be obtained. In this thesis the third ratio will be
referred to as the 6R:36R - 36:6RF ratio.

The desired pulsation ratios were obtained by modifying
the standard De Laval timer-converter, as shown in Figure l.
The mercoid switch had been removed and replaced with a ro-
tating cam. The cam rotated at the speed of the electric
motor in the timer—converter, in this case approximately R8
revolutions per minute. This caused the milker to milk at a

constant pulsation rate of R8 pulsations per minute.

Figure 1.

The modified De Laval timer-converter used for

obtaining pulsation ratios.

23

 

2h

The rotating cam activated a micro switch by means of
an arm which pressed against the perimeter of the cam. When
the raised portion of the cam pressed against the arm, the
arm was moved upward so that the micro switch was closed and
a current was allowed to pass through the switch and to the
solinoid on the stall cock. When the lowered portion of the
cam was pressed against the arm, the arm was lowered and the
micro switch Opened, thus stopping the flow of current to the
solinoid at the stall cock.

The solinoid on the stall cock Operated a valve which
when raised would admit atmospheric air to the outer chamber
of the teat cup. When the valve was lowered the outer cham-
ber of the teat cup would be opened to the vacuum line and
the air would be pumped out of the outer chamber by the
vacuum pump.

When the electrical current was passed through the
solinoid, the valve was raised. When the current was stopped,
the valve was lowered. Therefore the rest phase of the pulsa-
tion corresponding to the length of time current was passed
through the solinoid, which in turn was the length of time
the micro switch was closed.

The length of time the micro switch was closed in re—
lation to the length of time it was open was determined by
the portion of the cam which was raised in relation to the
portion which was not raised.

The cam was so constructed that the raised portion

could be adjusted to any particular pulsation ratio desired,

25

within certain limits.

The cam was composed of two discs, each of which had
a raised portion. The discs could be adjusted so that the
raised portion of the entire cam could be lengthened or
shortened. It was by changing the length of the raised por-
tion of the cam that the various pulsation ratios were ob-
tained.

The vacuum recorder, as described by Noorlander (28),

was used to check the setting of the timer-converter in order

that the desired pulsation ratio could be obtained. The
50:50 pulsation ratio on all four quarters was obtained by
setting the timer-converter for a 50:50 ratio, and by using
the standard De Laval milker claw and pulsator. To obtain
the 6R:36 pulsation ratio on all fOur quarters the timer-
converter was set for a 6R:36 ratio, one air port of the
standard De Laval claw and pulsator was closed, and a single
air hose was used to connect the milker claw and pulsator.
Figure 2 shows the converted claw, and Figure 3 shows the
converted pulsator.

The 6R:36R - 36:6RF pulsation ratio was Obtained by
setting the timer-converter for a 6R:36 ratio and using the
standard pulsator with a double air hose. The air ports in
the milker claw were by-passed by brazing three-eighths inch
copper tubing together in such a way, as shown in Figures R
and 5, that a front to rear milking action could be had. A
hole was drilled midway in a three inch piece of OOpper

tubing, and to this drilled hole another three inch piece of

Figure 2.

26

The converted standard De Laval milker claw used

to Obtain the 6R:36 pulSation ratio.

 

Figure 3.

The converted standard De Laval pulsator used to

obtain the 6R:36 pulsation ratio.

27

 

Figure R.

A device used to by-pass the air ports of the

standard De Laval milker claw.

28

 

Figure 5.

A device attached to the standard De Laval

milker claw, used to by-pass the air ports.

29

 

30
tubing was brazed, making a tee. Two tees were made with the
stem of one being an inch shorter than the other, the shorter
tee being brazed to the tOp side of the longer one in such a
way that the ends of the stems were in line vertically. A
clip was brazed to this double tee so it could be fastened
to the milker claw.

By attaching the double air hose from the pulsator to
the stem ends of this device and making sure that the cross
ends of the top tee were attached by single air hose to the
teat cups for the two front quarters, and the cross ends of
the bottom tee were attached to the teat cups for the two
rear quarters, a front to rear milking action was obtained.

With the above device in place and the timer—converter
set for a 6R:36 ratio, one side of the double air hose oper-
ated on a 6R:36 ratio, and the other side operated on a 36:6R
ratio. The vacuum recorder was used to indicate which side
of the double hose operated on the 6R:36 ratio, and this side
was attached to the bottom stem of the tee that Operated the
teat cups for the two rear quarters. This gave a 6R:36 ratio
to the two rear quarters, and a 36:6R ratio to the two front
quarters. The stem end of the lower tee was painted red as
was also the 6R:36 side of the double air hose so that no
mix-up would be made during the assembling of the machines.

The equipment used for the three ratios mentioned
above was very similar to standard milking equipment and did
not appear as strange objects near the cows during milking.

The milking routine ran just as smoothly as it did with the

31
standard equipment. In all three ratios the milk was carried

from the milker claw to the pipe line in the usual way.

The Recording Milk-O-Meter

 

In this experiment the recording Milk-O-Meter as de-
scribed by Hupp (25) was used to collect milk flow data. The
Operating parts of this meter are the same as in the regular
Milk-O-Meter, except that two electrical contacts have been
added so that each time the weigh tray trips, an electrical
impulse is sent to the recorder. This impulse from the meter
is carried by a wire which is plugged into a jack. One jack
is located behind each.Milk-O-Meter mount in the barn. These
jacks are connected to a low voltage wire which goes all the
way around the barn and leads to the recorder. Each time the
recorder receives an impulse from the meter, it makes a mark
with an indelible marker on a tape which is driven past the
marker at a constant speed. The recording meter can be used
for any cow in the milking line Of the barn with the recorder

located in one place.

Procedure for Collecting Data

Since it has been fairly well established that with
equal intervals between milkings there is very little dif-
ference between a.m. and p.m. milk yields (11, 25, 27, 33),
data were collected from the evening milkings only for this

experiment.

32

Only one recording Milk-O-Meter could be used, so
data were collected from one-third of the herd each day.
During a period of nine days three observations were made
from each cow with two days between each observation.

A two—week period divided into two parts was used for
each pulsation ratio. Four days were allowed for an adjust-
ment of the cows to the new ratio, while the second part con-
sisted of the nine days in which the data were collected.

Each treatment was repeated once, but in a different
order as shown in Table I. This gave a total of six obser4
vations from each cow for each treatment except for the

6R:36R - 36:6RF ratio. While collecting data on the 6R:36R -

TABLE I

The Order in Which Data Were Collected
For Three Pulsation Ratios

 

 

 

Treatment Pulsation Ratio Number No. Observations
of Weeks Per Cow
I 50:50 Entire Udder 2 3
II 6R:36 Entire Udder 2 3
III 6 :36 Rear Quarters
3 :6R Front Quarters 2 3
II 6R:36 Entire Udder 2 3
III 6R:36 Rear Quarters
36:6R Front Quarters 2 O

I 50:50 Entire Udder 2 3

33
36:6RF ratio the second time, a number of the cows became
very nervous and a few developed adverse udder conditions.
Because of this the treatment was discontinued. This left a

total of only three observations for this ratio.

Milking Rates

 

In addition to the graphic record made of each milking
by the recorder, a stop watch was used to obtain the total
milking time for each cow, this time being taken from the
time the teat cups were placed on the teats until they were
removed. The total pounds of milk produced were taken from
the tape in the Milk-O-Meter and the average flow rate for
each cow was determined by dividing the total pounds of milk
produced by the total milking time.‘

The data used to determine peak flow rates were ob-
tained from the recording Milk-O-Meter. The Milk—O-ueter
records in quarter-pound increments, and each tine the re-
corder received an impulse from the meter it made a mark with
an indelible marker on a tape that was driven past the marker
at a constant speed. Figure 6 shows a tape that was used
with the recording Milk-O-Meter. The distance between each
indelible mark represents one—quarter of a pound.

Each division on the tape equals a second, with 15
divisions to the inch. Since all the cows for one milking
were placed on one long tape, a pencil line was placed across
the tape and the number of the cow written in to show when

the start and the end of milking took place for each cow.

Figure 6.

A graphic recording tape used with the recording

Milk-O-Meter.

3A

 

 

 

0000;.

WI. ] l::l:n.l.zl.,:li'sia

      

=1
'lmzlszul.than] i. ;

 

 

 

 

 

 

35

The record on each cow was checked in several places
on the tape in order to find the greatest flow rate. In
the area of the greatest flow rate five pounds of milk were
marked off and the number of seconds or minutes were re-
corded that covered this area. These data were converted
into pounds per minute for peak flow rates. In two cases
the milk yield was not large enough to mark Off five pounds
for the greatest flow rate, so two pounds of milk were used
in place of five.

A simple device shown in Figure 7 was constructed to
facilitate the reading of the tapes. The roll of tape was
placed on the roller at one end and stretched over the
board and attached to the roller at the other end. By
turning the handle the tape could be rolled out over the

board and read.

The Milk Quality Test

 

There were some changes in the regular milking routine
in that a small quantity of milk was removed from each quar-
ter before udder preparation and after udder preparation, a
composite sample was taken with the Milk-O-Meter butterfat
sampler, and some strippings were taken after the completion
of milking. These samples were used to determine the effect
of the above ratios on udder irritation, which was determined
by the use of the Milk Quality Test, with some alterations,

as described by Noorlander (28).

Figure 7.

A device used to facilitate the reading of the

graphic tapes.

36

 

37

The Milk Quality Test is a screening device for de-
tecting abnormal milk due to irritation in the udder. Chem-
icals in the reagent that is used in the Milk Quality Test
condense or thicken the protein found in the white blood
cells or in the cytoplasm of damaged tissue. The degree of
thickening or viscosity will show the concentration of these
white blood cells in the milk. The geometric average cell
count from milk of healthy cows has been found to be 70,000
per millimeter. Any thickening that persists will indicate
over 500,000 body cells per millimeter of milk, and is an
indication of udder irritation. When the Milk Quality Test
is applied to abnormal milk the reaction due to the reagent
starts to thicken when the leucocyte count exceeds 250,000
per millimeter, and becomes a very thick viscous gel at
5,000,000 cells per millimeter. The quality of the milk is
scored according to.the thickness of this reaction. No re-
action is represented by a score of "O" and indicates no
irritation, a score of 1 represents a slight thickening or
cell count of about 500,000 cells per millimeter, a score
of 2 indicates a medium thickening with a cell count of
2,500,000, a score of 3 represents a very thick gel and an
indication of 5,000,000 or more cells per millimeter.

The irritation study was a separate project being car-

ried on simultaneously by another investigator.

RESULTS AND DISCUSSION

In Table II the data are presented showing the effects

of three different pulsation rates on the average flow rate

TABLE II

Average Flow Rates and Peak Flow Rates Obtained From
Three Pulsation Ratios
Part A

 

Pulsation Ratios*

I II III I II III
Average Flow Rate Peak Flow Rate

 

 

 

 

lbs./min. lbs./min.

Cow No. Brown Swiss

3078 2.85 R.25 3.86 R.36 R.80 5.20
30R7 R.56 R.85 R.00 7.09 7.28 7.23
3068 3.R7 3.03 2.12 5.66 6.32 6.55
3008 5.31 6.23 5.12 6.5R 7.73 6.22
3OR8 3.56 3.31 2.9R R.66 R.96 R.39
3077 3.85 3.52 3.18 5.11 5.91 5.11
Mean 3.93 R.20 3.5R 5.57 6.17 5.78
1157 3.80 3.35 3.20 6.10 6.57 6.71
1181 2.51 2.53 2.20 R.7l 5.71 R.7O
118R 2.13 2.38 1.86 3.30 R.O2 3.53
1185 1.97 2.00 2.26 3.8R R.5R 3.66
11R9 2.98 3.21 3.22 5.8R 6.67 5.90
Mean 2.68 2.69 2.55 R.76 5.50 R.90

 

*Pulsation Ratios:

I--A 50:50 ratio on the entire udder.
II--A 6R:36 ratio on the entire udder.

III--A 6R:36 ratio on the rear half and a 36:6R ratio on
the front half of the udder.

38

TABLE II--Continued

Part B

39

 

 

Pulsation Ratiosfi

 

 

 

 

I II III I II III
Average Flow Rate Peak Flow Rate
lbs./min. lbs./min.

Cow NO. Holstein
609 5.08 5.35 R.90 7.RS 7.78 7.20
626 3.R8 R.Rl R.OO R.72 6.12 5.59
572 2.R5 2.81 3.18 5.13 6.21 5.21
596 5.19 5.8R 6.22 9.15 10.96 10.25
638 2.30 3.RR 2.3R 3.10 3.R7 3.16
686 3.50 R.R7 3.58 6.96 8.86 7.17
A110 3.0R 3.R0 3.0R 6.20 7.52 7.38
630 3.R6 3.97 3.16 R.38 5.22 R.21
A 78 2.22 2.01 2.10 7.08 8.6R 5.97
5R2 R.l7 3.50 R.31 8.33 8.85 8.69
685 3.RR R.00 2.72 R.R9 5.Rl R.76
'6R0 3.53 3.16 2.5R 5.82 6.32 5.81
608 5.59 R.9l 5.30 7.69 9.03 8.67
6R3 R.5l R.R6 R.78 7.81 9.22 8.37
6R9 R.3O R.26 3.8R 5.56 6.89 5.73
612 5.69 6.5R 6.08 7.R6 8.69 8.0R
598 3.65 R-l7 3.50 5.89 7~R9 7.73
K302 R.1O R.01 5.16 6.21 7.61 6.97
6RR 2.65 3.3R 2.6R 3.68 R.39 3.86
606 5.16 6.10 R.5R 8.R9 9.99 9.09
693 1.9R 2.36 2.06 2.50 2.88 2.77
6R1 R.6l R.98 3.58 6.88 7.31 6.RO
63R 2.70 2.93 2.9R R.91 5.91 5.17
Mean 3.77 R.ll 3.76 6.51 7.16 6.RR

 

fiPulsation Ratios:

I--A 50:50 ratio on the entire udder.
II—-A 6R:36 ratio on the entire udder.
III--A 6R:36 ratio on the rear half and a 36:6R ratio on

the front half

of the udder.

R0
and the peak flow rate for the individual cow, and the mean

rate for each breed.

Averagg Flow Rate

The results of this experiment indicate a slightly
larger average milk flow rate as shown in Table III when the
6R:36 pulsation ratio was used, with the 50:50 ratio and the
6R:36R - 36:6RF ratio following in that order. Within the
Holstein breed the average milk flow rate was R.1l pounds per
minute when the 6R:36 pulsation ratio was used, as compared
with 3.77 pounds per minute for the 50:50 ratio, and 3.76
pounds per minute for the 6R:36R - 36:6RF ratio. With the
Brown Swiss breed R.2O pounds per minute were obtained from
the 6R:36 ratio, 3.93 pounds per minute from the 50:50 ratio,
and 3.5R pounds from the 6R:36R - 36:6RF ratio. .The average
milk flow rate within the Jersey breed was as follows: 2.69
pounds per minute with the 6R:36 ratio, 2.68 pounds per
minute with the 50:50 ratio, and 2.55 pounds per minute with
the 6R:36R - 36:6RF ratio. The mean for all breeds follow
the same pattern: 3.91 pounds per minute with the 6R:36
ratio, 3.6R pounds per minute with the 50:50 ratio, and 3.5R
pounds per minute with the 6R:36R - 36:6RF ratio.

Analysis Of variance shows significant differences
(P>0.0l) between the breeds for the average rate of milk
flow, thus verifying the work done by Beck and his co-
workers (R). The difference between the ratios is not sig-

nificant.

Rl
TABLE III

The Mean Differences in Average Flow Rate and Peak Flow Rate
For Three Dairy Breeds

 

 

Pulsation Ratiosfi

 

 

 

I II III I II III
Average Flow Rate Peak Flow Rate
—-lbs./min. --—lbs./min.--

Breed No. of

Cows

Holstein 23 3.77 R.ll 3.76 6.51 7.16 6.RR
Brown Swiss 6 3.93 R.20 3.5R 5.57 6.17 5.78
Jersey 5 2.68 2.69 2.55 R.76 5.50 R.9O
All Breeds 3R 3.6R 3.91 3.5R 5.80 6.7R 6.10

 

*Pulsation Ratios:
I--A 50:50 ratio on the entire udder.
II--A 6R:36 ratio on the entire udder.
III--A 6R:36 ratio on the rear half and a 36:6R ratio on
the front half of the udder.

When the Brown Swiss cows were milked with the 50:50
ratio and with the 6R:36 ratio their flow rates exceeded the
Holstein and Jersey breeds in that order. The Holstein breed
exceeded the Brown Swiss and Jersey breeds in that order when

milked with the 6R:36R - 36:6RF ratio as shown in Table III.

Peak Flow Rate

 

The results obtained for the peak flow rates do not
follow the same pattern as those for the average milk flow

rates. With the Holstein breed, differences between the

AZ
pulsation ratios are similar to those of the average milk
flow rates. The 6h:36 ratio gave the highest peak flow,

7.16 pounds per minute, with the 50:50 ratio giving the next
to the highest peak flow rate, 6.51 pounds per minute, and
the 6h:36R - 36:6hF ratio giving the lowest peak flow rate,
6.uu pounds per minute. However, as shown in Table III,
with both the Brown Swiss and the Jersey breeds the 6h:36R -
36:6HF ratio gave the next to the highest peak flow rate,
5.78 pounds per minute for the Brown Swiss and b.90 pounds
per minute for the Jerseys. In both the Brown Swiss and
Jersey breeds the 6u:36 ratio gave the highest peak flow
rate, 6.17 pounds per minute for the Brown Swiss, and 5.50
pounds per minute for the Jerseys. The 50:50 ratio gave the
lowest peak flow rate for the Brown Swiss and Jersey breeds,
5.57 pounds per minute for the Brown Swiss, and n.76 pounds
per minute for the Jersey. No precise explanation can be
given for this difference.

The mean rate for all breeds follows the same pattern
as that for the Brown Swiss and Jersey breeds, with the 64:36
ratio exceeding the 6A:36R - 36:6uF ratio and the 50:50 ratio
in that order. The peak flow rates for all breeds are as
follows: 6.7a pounds per minute for the 6h:36 ratio, 6.10
pounds per minute for the 6h:36R - 36:6MF ratio, and 5.80
pounds per minute for the 50:50 ratio.

As with the average milk flow rates, analysis of vari-
ance shows a significant difference (P>0.0l) between the

breeds for peak flow rates. The difference between the

#3

ratios approaches significance at the five percent level

for the peak flow rates.

TABLE IV
The Average Milk Yield Per Milking and Machine Time

As Obtained From Three Pulsation Ratios
Part A

Pulsation Ratios*

 

 

I II III I II III
Milk Yield Machine Time
II lbs. per milking -———-—minutes
Cow No. Brown Swiss
3078 17 2h 26 6.1 6.0 6.6
30u7 30 29 26 6.6 6.0 6.3
3068 1h 13 13 u.3 u.u 5.5
3008 30 32 30 5.7 5.6 5.8
30MB 25 23 2a 7.0 7.5 8.2
3077 18 19 18 u.7 5.3 5.7
Mean 22 23 23 5.7 5.8 6.u
Jersey

1157 l7 l6 l7 u.6 u.8 5.u
1181 9 9 9 3.6 3.7 h-l
118A 9 9 9 u.3 3.8 u.7
1185 9 10 10 u.5 5.0 u.3
11u9 15 16 15 5.1 5.0 u.7
Mean l2 l2 l2 u.u u.5 u.6

 

*Pulsation Ratios:
I--A 50:50 ratio on the entire udder.
II--A 6uz36 ratio on the entire udder.
III--A 6h:36 ratio on the rear half and a 36:6u ratio on
the front half of the udder.

TABLE IV--Continued

Part B

 

 

Pulsation Ratiosfi

 

 

 

 

I II III I II III
Milk Yield Machine Time
lbs. per milking minutes

Cow No. Holstein
609 30 31 30 6.0 5.7 6.2
626 21 22 23 6.1 8.9 5.8
572 17 17 17 6.8 6.8 5.7
596 27 27 30 5.5 11$? 8.8
638 20 23 20 9.1 9.2 9.2
686 17 19 18 8.9 8.8 5.1
A110 15 16 17 5.2 5.5 5.5
630 19 20 18 5.6 5.1 6.3
A 78 10 10 11 8.7 5.1 5.0
582 16 16 16 3.9 8.6 3.9
685 20 20 20 5.9 5.1 6.1
680 16 17 16 8.9 5.3 6.2
608 27 29 32 5.0 6.0 6.0
683 21 21 23 8.6 8.8 8.8
689 26 211 23 5.3 5.6 6.0
612 38 33 35 6.1 5.1 5.7
598 19 22 23 5-7 5.3 6.5
K302 23 22 26 5.8 5.3 5.6
688 18 18 18 6.8 5.5 6.9
606 28 25 28 8.7 8.1 5.8
693 15 15 16 8.0 6.5 7.5
681 20 22 20 8.8 8.8 6.1
638 13 13 13 5.1 8.6 8.2
Mean 20 21 21 5.7 5.8 5.9

 

*Pulsation Ratios:
I—-A 50:50 ratio on the entire udder.
II-—A 68:36 ratio on the entire udder.

III--A 68:36 ratio on the rear half and a 36:68 ratio on

the front half of the udder.

L15

Machine Time

 

The results for machine time and milk yield for each
cow and the individual breeds, are presented in Table IV.

As presented in Table V there is very little dif-
ference between the ratios in machine time. In all three
ratios the Jersey breed required the least time to milk out,
but the milk yields for the Jerseys in all three ratios were
much lower than those for the Holstein and Brown Swiss, a

fact which may account for the lower machine time.

TABLE V

The Average Milk Yield and Machine Time By Breed
As Obtained From Three Pulsation Ratios

 

 

Pulsation Ratios*

 

 

 

 

I II III I II III
Milk Yields Machine Time
Ibs. per milking minutes
Breed No. of
Cows
Holstein 23 20 21 21 5.7 5.8 5.9
Brown Swiss 6 22 23 23 5.7 5.8 6.8
Jersey 5 12 12 12 8.8 8.5 8.6
All Breeds 38 19 20 20 5.5 5.3 5.8

 

*Pulsation Ratios:
I-—A 50:50 ratio on the entire udder.
II--A 68:36 ratio on the entire udder.
III--A 68:36 ratio on the rear half and a 36:68 ratio on
the front half of the udder.

86
TABLE VI

The High, Low, and Average Machine Time for the Holstein,
Brown Swiss and Jersey Breeds

 

 

Pulsation Ratios*

 

 

 

 

I II III
minutes
Holstein
High 9.1 9.2 9.2
LOW 309 he]. 3'9
Average 5.7 5.8 5.9
Brown Swiss
High 7.0 7.5 8.2
LOW 14.03 “-0,-6- 5.5
Average 5.7 5.8 6.8
Jersey
High 5.1 5.0 5.8
Low 3.6 3.7 8.1
Average 8.8 8.5 8.6
All Breeds
High 9.1 9.2 9.2
LOW 306 307 3'9
Average 5.5 5.3 5.8

 

*Pulsation Ratios:
I--A 50:50 ratio on the entire udder.
II--A 68:36 ratio on the entire udder.
III--A 68:36 ratio on the rear half and a 36:68 ratio on
the front half of the udder.

As shown in Table VI, variation in machine time for
all cows and all three ratios range from 9.2 to 3.6 minutes,
with an average of 5.6 minutes per cow. Cow Number 638,
known to be a hard milker, has the highest machine time in
all three ratios as shown in Table IV.

When the 50:50 ratio was applied, a Holstein cow

LL?

required the longest time to milk out, 9.1 minutes, and a
Jersey cow required the least, 3.6 minutes. This was also
the case with the 68:36 ratio; a Holstein cow required 9.2
minutes to milk out, whereas a Jersey cow required only 3.7
minutes to milk out. For the 68:36R - 36:68F ratio the
highest and lowest machine times were obtained from two cows
of the Holstein breed, with a high of 9.2 minutes and a low
of 3.9 minutes.

When comparing the ratios for the percentage of cows
milked out in 5.0 minutes or less and 8.0 minutes or less,
it was found that for the 50:50 ratio and the 68:36 ratio
81 percent of the cows were milked out in 5.0 minutes or
less, and 6 percent were milked out in 8.0 minutes or less.
For the 68:36R - 36:68F ratio 26 percent of the cows milked
out in 5.0 minutes or less, and 3.0 percent in 8.0 minutes
or less. When considering all the cows and all three ratios
together, 36 percent of the cows milked out in 5.0 minutes

or less and 5.0 percent in 8.0 minutes or less.

Udder Irritation

As mentioned above, while applying the 68:36R - 36:68F
ratio the second time, some adverse udder conditions were
noticed with some cows, while a number of the cows became
very nervous and would move back and forth while being

milked. In a few individual cases it appeared that the cows

held up their milk.

O

88

It is difficult to know how these conditions came
about. There is a possibility that either the front or rear
quarters were over-milked causing udder irritation and
general discomfort to the cow. If this were the case, these
conditions might have been avoided if two different pulsa-
tors had been used, one to control the rear quarters and
one to control the front quarters. With separate pulsators
the teat-cups on the rear quarters can be in Operation while
those on the front quarters are inactive, or vice versa.
There is also a possibility that irritation started with a
previous treatment may have reached its peak during the
second replica of this ratio, causing general discomfort
and irritation to the udder.

The Milk Quality Test results show the least irrita-
tion with the use of the 68:36 pulsation ratio, and the

greatest irritation with the 50:50 pulsation ratio.

SUMMARY

Comparisons were made of the effects of three dif-
ferent pulsation ratios on the average milk flow rate and
peak flow rate. These pulsation ratios consisted of a 50:50
ratio and a 68:36 ratio which were applied to the entire
udder, while the third was a variable ratio using a 68:36R
(R indicates rear) ratio for the rear half, and a 36:68F
(F indicates front) ratio for the front half of the udder.

Thirty-four cows, consisting of 23 Holstein, 6 Brown
Swiss, and 5 Jerseys, were used in this study. Data were
collected from these cows during the evening milkings. For
the 50:50 and 68:36 pulsation ratio six observations were
made on each cow. Some adverse udder conditions arose during
the second replica of the 68:36R - 36:68F pulsation ratio,
and because of this, only three observations were made on
each cow for this ratio.

A timer-converter was develOped so that the three
desired pulsation ratios could be obtained. The standard De
Laval milker claw and pulsator were adapted to fit the de-
sired ratios obtained by the timer-converter. A vacuum re-
corder was used to check the setting of the timer-converter
to be sure that the proper pulsation ratios were obtained.
The recording Milk-O-Meter was used for collecting the data
on milk flow rates and machine time.

The Milk Quality Test was used with each pulsation ratio

to detect any irritation that might occur in the udder.

119

CONCLUSIONS

From this study the results indicate that a slightly
higher average flow rate and peak flow rate were procured
when the 68:36 ratio was used as compared with the 50:50
ratio and the 68:36R - 36:68F ratio. The 50:50 ratio gave
a slightly higher average flow rate than that obtained by
the 68:36R - 36:68F ratio.

With the Brown Swiss and Jersey breeds the 68:36R -
36:68F ratio showed a slightly higher peak flow rate than
that of the 50:50 ratio. For the Holsteins the ratios ran
from highest to lowest in peak flow rates in the following
order: the 68:36 ratio, the 50:50 ratio, and the 68:36R -
36:68F ratio.

Analysis of variance showed a highly significant dif-
ference between breeds for both average milk flow rate and
peak flow rate. There were no significant differences be-
tween the ratios.

There was very little difference in machine time
among the three ratios.

Irritation appeared to be more prevalent when the
50:50 pulsation ratio was used, while the 68:36 pulsation

ratio gave the least irritation.

50

10.

ll.

12.

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