Variation in the Constituents of Milk Under Arizona Conditions. III. Variation in Milk from Jersey, Guernsey, Holstein, and Mixed Herds

VARIATION IN T H E CONSTITUENTS OF MILK UNDER ARIZONA CONDITIONS. III. VARIATION I N MILK FROM JE RSE Y , GUERNSEY, HOLSTEIN, AND MIXED H E RD S R. N. D A V I S AND F. G. H A R L A N D

Depart~nent of Dairy Husbandry A. B. C A S T E R AND R. It. KELLI~ER~

Depart~nent of Agricultural Chemistry and.Soils, University of Arizona, Tucson

Considerable daily variation is known to occur in the composition of milk of individual cows of each breed. The milk, however, usually is sold not from individual cow~ but from herds of cows. Individual variations among cows, therefore, are of less significance in mixed milk. Herds producing milk having low fat and serum solids tests can be changed to include other animals of the same breed or other breeds which produce milk higher in fat and serum solids. This study is concerned with the variations in the composition of the milk from herds of Jerseys, Guernseys, Holsteins, and mixtures of two or more breeds and from herds maintained in good physical condition as compared with marginal herds. REVIEW OF LITERATURE

Lythgoe (6) reported 45 analyses of samples from herds in which the total solids, fat, serum solids, and protein were higher in winter and lower in summer. Jacobson (4) reported on the analyses of over one hundred thousand samples of mixed milk and found that serum solids increased consistently 0.04 per cent with each 0.10 per cent increase in fat. This investigator also observed that milks containing 3.2 to 4.8 per cent fat showed considerably lower serum solids in winter than did the milks containing 4.9 to 5.7 per cent fat. July, August, and September were characterized by a reduction in serum solids values. Little (5) studied the chloride content of milk from 24 cows at various stages of lactation. He reported that during the first 4 months of lactation, 90 per cent of the chloride values were under 0.14 per cent, as compared to 13.4 per cent under that value after 8 months or more of lactation. Sharp and Struble (8) conducted monthly chloride titrations on thirteen Jersey, eight Guernsey, and fifteen Holstein cows. These investigators noted a rapid decline in chlorides during the first few days, a slight increase during the first 60 per cent of the lactation, and a marked increase during the final 10 per cent of the lactation period. Sharp and H a r t (7) reported that, on results of ten samples, lactose had very little significance in the variation of specific gravity. Gaines (3) Received for publication ~/[areh 31, 1947. 1 Resigned J u l y 1, 1942. 435

436

R. 1~'. DAVIS, ET AL.

studied the milk of 52 cows of various ages, weights, and breeds, and concluded that the secretion of fat and protein appear intimately related. The ratio of fat to protein reported by this investigator was 1 : 0.812 ± 0.010, and this relationship was applicable to a fat range in the milk from 0.36 to 22.46 per cent. EXPERIMEI~TAIJ

The milk samples analyzed in this study were obtained from two purebred Jersey, one purebred Guernsey, three purebred Holstein, and five mixed herds, each of 30 cows or more. Representative samples were taken monthly from the mixed milk of each herd. The butterfat content was determined by the Babcock method, total solids by the Mojonnier method, and serum solids by ealcflation of difference. The polariscope was used to analyze for lactose. Total nitrogen percentage was obtained by the Kjeldahl method; the total nitrogen then was multiplied by the factor 6.40 to give the percentage of protein. The specific gravity was determined by use of a hydrometer. The chloride determinations were made by direct titration with tenth normal silver nitrate in the presence of potassium chromate. The.data collected on the four groups of herds are presented in figures 1 to 4, inclusive. The data represent 48 tests on the milk from Jersey herds, 20 from Guernsey herds, 50 from Holstein herds, and 120 from the mixed herds. The tests were made over a period of 2 years. The maximum, minimum, and average values for the constituents of milk are presented by TABLE 1

Maximum, minimum, and average per cent of different constituents of mil~ for the four groups of herds

Jersey ~[ax ....... ~kV ..........

Ratio serum solids to f a t

Specific gravity

0.13 0.06 0.11

2.41 1.41 1.89

1.0355 1.0310 1.0348

3.6 3.1 3.3

0.21 0.11 0.13

2.36 1.89 2.11

1.0360 1.0305 1.0341

5.3 4.1 4.7

3.2 2.2 2.9

0.19 0.13 0.15

2.79 1.80 2.43

1.0345 1.0305 1.0323

5.4 4.2 4.6

3.6 2.4 3.2

0.16 0.09 0.13

2.65 1.69 2.28

1.0355 1.0310 1.0330

Chlorides

Total solids

Serum solids

Fat

:Lactose

Protein

(%)

(%)

(%)

(%)

(%)

(%)

15.4 13.1 14.2

10.1 8.1 9.3

5.7 4.1 4.9

5.4 4.4 4.8

3.9 2.9 3.5

14.3 12.2 13.6

9.7 8.2 9.2

4.8 3.9 4.4

5.2 4.4 4.8

12.9 11.1 12.0

9.1 7.7 8.5

4.4 3.0 3.5

13.7 11.8 12.{}

9.2 8.0

5.0 3.3

8.8

3.8

Guernsey Max ....... ~kV ..........

Holstein l~ax ....... ]~Iin....... ~kV ..........

Mixed ]~ax ....... Min ....... ~kV ..........

437

VARIATIONS IlkT ]YIILK C O N S T I T U E N T S

JERSEY HERDS

14.8 14.3 13.8 9.6

t

,

'

'

'

'

'

~SERUM

'

'

SOLIDS

'/',.I

~

9.1

4.8 m

t'

5;

5.05

4.55 3.7O

--

3.45

-

P

0.125

R

0.100 1:2.05

R

O

~

~ I

D

E

~

-

-

~

"

I: 1.85 I: 1 . 6 5 -

1.0356 1.0346

~

RATIO

FAT:

SERUM

SOLIDS/.

-

v

1 . 0 3 3 6 I-I I I I I I I 1 I I --JAN. FEB. MAR. APR, MAY dUNE JULY AUG. SEPT. OCT. NOV. DEC,

FIG. 1. Variations in constituents of milk from Jersey herds by calendar months. groups in table 1. Table 2 represents the percentage variation in composition of milk from winter to summer. Figures 1 to 4 show that the total solids, serum solids, fat, protein, and lactose content of milk from each group of herds were lowest in summer and highest in winter. Table 2 shows the percentage decrease in total solids,

438

R.N. DAVIS, ET ~ .

G U E R N S E Y HERDS 14.1

. . . . . . . . .

-t 900 I--

8.75 4 . 7 5 ~ 4.50 I-- ~ n

~

v

Jl J--!

~

4.00

~

5

-1

SERUMSOLIDS\ ~

.

2

,..,

,

~

4.7

3.5 0.140 ~ _

.

.

.

~'"

'~

~

~-

0.115 1:2.00

~

J:l.eo

--

RATIO FAT: SERUM S O L I D S T '

JAN.FEB. MAR.APR. MAY JUNEJULYAUG.SEPT.OCT.NOV. DEC. Fire 2.

Variations in constituents of milk from Guernsey herds by calendar months.

serum solids, fat, lactose, and protein and the increase in the chloride content of the milk from each of the four groups. The specific gravity of milk from Jersey, Guernsey, Holstein, and mixed herds averaged 1.035, 1.034, 1.032, and 1.034, respectively, in winter and 1.034, 1.034, 1.032, and 1.033, respectively, in summer.

VARIATIONS IN

I~ILK

439

CONSTITUENTS

HOLSTEIN HERDS 12.9

I

I

I

I

I

I

I

I

I

I

12.4 I

11.9

,1,, ~ 8.8 ~ 8.5 ; 8.3

~ D

4.9

S~

,

~

~

~.

o 3x ~ ,.=, n

~~F

A

~

_

=

-

LACTOSE\.

4.0 3.0

~

~

2.5

-

V'

0.155 0.130

-

--

UHLUI'(I

UI:.:5"

--

1:2.4 1:2.2

~.

1.0318

1 I I I I I I I i JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT, OCT, NOV. DEC. ]~I(]. 3. Variations in constituents of milk from Holstein herds by calendar months. The average chloride content of the milk f r o m the f o u r groups of herds was higher in summer t h a n in winter. The winter chloride values for the Jersey, Guernsey, Holstein, and mixed herds were 0.10, 0.12, 0.14, and 0.12 p e r cent, respectively. The corresponding values for the summer months

440

R. :N'. DAVIS~ ET AT,.

MIXED HERDS

13.8

I

I

I

I

I

'1

I

I

I

I

B

13.3 12.8 12.3

~'~

9.15 L , ~ ~ ~ , = , ~ E R U

M SOLI

e.65i-

~

85O

I.d 0 4.5 IZ: 3.9 bJ I1. 3.3

Jr

FAT

5.0 4.4 4.0

-1

v

LAGTOSE,~ PROTEINx~

_

2.8

o.115 0.09 1:2.3 1:2.2 1:2.1

i.o34

"

~

~

,'v-

~ SPEGIFIG GRAVITY ~:

/

I .033 1.032

JAN. FEB. MAR. APR. MAY JUNEJULYAUG.SEPT.OCT. NOV. DE(;. FIG, 4.

Yariations in constituents of milk from mixed herds by calendar months.

were 0.12, 0.13, 0.16, and 0.13 per cent. The values for other constituents of milk from the mixed herds also are intermediate between the low Holstein values and the high Guernsey and Jersey values. This is due to the greater numbers of Holstein cows in the mixed herds.

VARIATIONS

IN

MILK

TABLE

2

Perventageofehangeofconstituentsofherd Breed

~onstituent Total solids Serum solids Fat Lactose Protein Chlorides

Jersey

(%)

4.35 1.39 - 9.78 - 2.06 2.80 + 14.17

-5.96 - 5.94 - 6.02 -4.52 -8.65

-

-

milk ~ o m w i n t e r t o s u m m e r

Guernsey

(%) -

441

CONSTITUENTS

+ 7.69

Holstein

Mixed

(%)

(%) -

3.88 1.42 9.51 - 9.30 4.22 + 10.62

-

i I

-

-

3.54 2.73 0.52

-

1 . 6 9

- 3.72 + 15.75

Three of the mixed herds were kept u n d e r marginal conditions of feeding. One of the purposes of this project was to compare the composition of the milk of these herds with that of milk from herds in which the cows were maintained in good physical condition. The total solids, serum solids, fat, lactose, protein, and chloride values and specific gravity for the herds in good physical condition were 12.7, 8.8, 4.0, 4.7, 3.2, and 0.13 per cent, and 1.0327, respectively. The corresponding values for the marginal herds were 12.5, 8.8, 3.7, 4.6, 3.2, and 0.13 per cent, and 1.0333 specific gravity. These data show that milk from marginal herds was slightly lower in total solids, fat, and lactose. This would indicate that the cow's body must be in a very poor physical condition to produce milk significantly lower in each o f the constituents. DISCUSSIOi'¢

The difference between maximum and minimum values of each constituent of herd milk shown in table 1 is less than corresponding values for milk from individual cows shown in the first p a r t of.this series (1). I n the second paper of this series (2), it was hoted that individual cows may produce milk abnormally low in serum solids although well above the minimum in fat. This is true of herd milk, but to a smaller degree. Of 199 samples collected from ten herds (two Jersey, one Guernsey, two Holstein, and five mixed) over a 2-year period, eleven samples were abnormally low in serum solids. The average fat and serum solids for the eleven samples were 4.42 and 8.08 per cent, respectively. The results of this study are in agreement with the work of Gaines (3). The average ratio of fat to protein varied from 1:0.721 for milk from Jersey herds to 1 : 0.830 for Holstein herd milk. Milk from mixed herds had a ratio of 1 : 0.813. SUMMARY

(1) Total solids, serum solids, fat, and protein values were highest in winter and lowest in summer. (2) The milk from Jersey and Guernsey herds, containing 4.91 and 4.36 per cent fat, respectively, showed no definite trends in lactose content in re-

442

R.N. DAVIS, ET AL.

]ation to other constituents. The milk from the Holstein and mixed herds had a slightly lower lactosevalue during the summer, with an increase in the fail and winter months. (3) The serum solids content of milk from Holstein cows was below 8.5 per cent during 6 months of the year. Thisdecline occurred in summer and was accompaniedby decreases in total solids, fat, and lactose. Serumsolids content of the milk from Jersey, Guernsey, and mixed herds also averaged lowest in summer, but was still above the legal minimum, except for mixed herds, which had an average of 8.48 per cent serum solids in August. (4) The average chloride values were 0.152 for the Holstein herds, 0.134 for the mixed, 0.128 for the Guernsey, and 0.110 per cent for the Jersey herds. The chloride values were highest in summer and ]owest in winter. (5) Cows on marginal rations and consequently not in good physical condition produced milk which is considered normal in composition and averaged only slightly lower in total solids, fat, and lactose, essentially the same in serum solids, and slightly higher in the protein content and in specific gravity. (6) Herd samples of milk representing one day's production may be abnormally low in serum solids but well above the minimum in fat. REFERENCES (i) DAvis, R. N., HARLAND, F. S., CASTER, A. B., AND KELLNER, R.H. Variation in the Constituents of Milk under Arizona Conditions. I. Variations of Individual Cows within Breeds by Calendar Months. Jour. Dairy Sci., 30: 415-424. 1947. (2) DAVIS, R. N., lCiARLAND,F. G., CASTER, A. B., AND KELLNER, R . H . Variation in the Constituents of Milk under Arizona Conditions. II. Influence of the Month of Lactation in Cows of Different Breeds. J our. Dairy Sci., 30: 425-433. 1947. (3) GAINES, W. L. Relative Rates of Secretion of Various Milk Constituents. Jour. Dairy Sci., 8: 486-495. 1925. (4) JACOBSON, M. S. B u t t e r f a t and Total Solids in New England F a r m e r s ' Milk as Delivered to Processing Plants. Jour. Dairy Sci., 19: 171-176. 1936. (5) LITTLE, R . B . The Effect of Advanced Lactation in the Cow on the Physical and Chemical Composition of Milk. Jour. Dairy Sci., 22: 689-695. 1939. (6) LYTHGOE, H. C. The Composition of Milk as Shown by Analyses of Samples of Known Purity Made by Massachusetts State Board of Health. Indus. and Engin. Chem., 6: 899-908. 1914. (7) SHARP, P. F., AND HART, R . G . The Influence of the Physical State of the F a t on the Calculation of Solids from the Specific Gravity of the Milk. Jour. Dairy Sci., 19: 683-695. 1936. (8) SttARP~ P. F., AND STRURLE, E . B . Period of Lactation and Direct Titratable Chloride Value of Milk. Jour. Dairy Sci., 18: 527-538. 1935.