|
GOAT MANAGEMENT
Composition Of Goat Milk And Factors Affecting It
By
George F. W. Haenlein
Cooperative Extension Dairy Specialist
University of Delaware
This is a summary in tabular form of recent goat nutrition research concerning ways of
changing goat milk composition, which is of great interest for tailor-making milk for human nutrition needs.
Addition of calcium salts of long-chain fatty acids increased milk fat content and yield without changing milk
protein contents (Table 1). C4 - C14 fatty acids in milk fat were decreased significantly,
while long-chain fatty acids increased including unsaturated acids and cholesterol.
Feeding fishmeal instead of soybean oilmeal as a protein source to dairy goats had no significant effects in
the long term and did not increase protein contents in goat milk (Table 2).
Decreasing forage:concentrate ratio to 45:55 depressed milk fat percent, increased protein content, milk yield
and weight gain, while decreasing eating and rumination time (Table 3).
Average milk composition of native goats, as, for example, in Greece varies over a wide range, which has good
selection potential (Table 4).
Feeding less rumen-degradable protein, as after formaldehyde treatment, decreases milk urea content (Table
5). Hydrolyzed feathermeal, another less-degradable protein had little significant effects on milk composition
(Table 6).
Feeding sodium bicarbonate buffer significantly improved fat and total solids percentage in goat milk but slightly
decreased protein content (Table 7).
With advancing stage of lactation the percent contents of fat, protein, casein, minerals, total solids, SNF,
sodium, calcium, phosphorus, magnesium, and the titratable acidity increase, while contents of lactose, potassium
and citrate significantly decrease (Table 8).
Comparatively, cow milk is low in copper, iron, zinc, manganese, calcium and magnesium contents, sheep milk
being highest in these minerals except for manganese, where goat milk is highest, otherwise goat milk is intermediate;
sodium is highest in cow milk,followed by sheep and goat milk, while potassium is highest in cow milk, followed
by goat and sheep milk (Table 9).
Odorous compounds in milk of 4 species are highest in water buffaloes for esters, aldehydes, ketones, alcohols,
N-compounds and overall, while sheep are highest for S- and aromatic compounds and cows for lactones. Goat milk
is lowest among the 4 species for esters, aldehydes, ketones, aromatic compounds and overall(Table
10).
Treatment with bST increased goat milk yield significantly, as well as some fatty acids and urea content, while
decreasing NEFA levels (Table 11).
Comparing goat milk with human milk composition shows that most components are higher in goat milk than human
milk except for ascorbic acid and vitamin B12 (Table 12).
With days after kidding or stage of lactation each protein in goat milk increases except for remainder whey
protein (Table 13).
Different sources of diet protein have little effect on cheese making properties of goat milk except for increasing
casein and overall protein contents (Table 14).
| Table 1. Effect of Added Calcium Salts (6%) of Long Chain Fatty Acids on Alpine Goat Milk Yield and Composition |
|
|
|
|
|
|
|
| |
Diet
|
Week
|
| |
Control
|
Fat
|
7
|
10
|
13
|
16
|
19
|
| Milk yield, kg/d |
3.3
|
3.4
|
3.7
|
3.8
|
3.1
|
3.2
|
2.8
|
| Fat, % |
3.4
|
3.7*
|
3.7
|
3.6
|
3.7
|
3.5
|
3.4
|
| 3.5% FCM yield, kg/d |
3.2
|
3.5*
|
3.5
|
3.7
|
2.9
|
3.2
|
2.9
|
| Protein, % |
2.6
|
2.6
|
2.7
|
2.7
|
2.6
|
2.6
|
2.6
|
| Fat yield, g/d |
112.5
|
127.6*
|
139.2
|
|
114.2
|
|
95.5
|
| Protein yield, g/d |
86.9
|
89.5
|
101.2
|
|
79.3
|
|
73.6
|
| Energy value, kcal/kg |
654
|
682*
|
681
|
|
679
|
|
649
|
| FA C4-14, % |
37.5
|
32.3*
|
|
|
|
|
|
| C16-16:1, % |
29.9
|
31.8*
|
|
|
|
|
|
| C18:0-18:3, % |
28.9
|
31.9*
|
|
|
|
|
|
| C6:0 |
2.9
|
2.8
|
|
|
|
|
|
| C8:0 |
3.4
|
3.0*
|
|
|
|
|
|
| C10:0 |
12.8
|
10.4*
|
|
|
|
|
|
| C12:0 |
4.7
|
3.4*
|
|
|
|
|
|
| C14:0 |
10.8
|
9.8*
|
|
|
|
|
|
| C16:0 |
28.3
|
29.9
|
|
|
|
|
|
| C16:1 |
1.6
|
2.1*
|
|
|
|
|
|
| C18:0 |
7.4
|
8.4
|
|
|
|
|
|
| C18:1 |
17.9
|
19.2
|
|
|
|
|
|
| C18:2 |
3.0
|
3.3
|
|
|
|
|
|
| C18:3 |
0.7
|
0.9*
|
|
|
|
|
|
| Plasma: |
|
|
|
|
|
|
|
| Triglycerides, mmol/L |
0.46
|
0.45
|
|
|
|
|
|
| Cholesterol, mmol/L |
3.5
|
4.3*
|
|
|
|
|
|
| P-lipids, mmol/L |
2.5
|
2.9*
|
|
|
|
|
|
| FFA, microequ/L |
281
|
287
|
|
|
|
|
|
| G-glutamltrpet-ase, U/L |
28.9
|
33.5*
|
|
|
|
|
|
| Weight change, kg |
-2.5
|
+0.3*
|
|
|
|
|
|
16 goats each; A. Baldi et al. (Univ. Milano, Italy), Small Rum. Res. 6(1992):303-310.
| Table 2. Effects of Protein Source on Milk Yield and Composition of Damascus Goats |
|
|
|
|
|
|
| Period |
I
|
II
|
III
|
| Protein source |
SBM
|
FM
|
SBM
|
FM
|
SBM
|
FM
|
| Milk yield, kg/d |
1.95
|
1.94
|
1.66
|
1.60*
|
2.34
|
2.44
|
| Fat, % |
4.22
|
4.04
|
4.25
|
4.49*
|
2.71
|
2.31
|
| Protein, % |
3.96
|
3.93
|
4.07
|
4.04
|
3.67
|
3.58
|
| Total solids, % |
12.80
|
12.79
|
12.98
|
13.01
|
11.46
|
10.98
|
| Minerals, % |
0.80
|
0.81
|
0.85
|
0.84
|
0.80
|
0.82
|
| Weight change, g |
62
|
68
|
-13
|
-59
|
8
|
-2
|
SBM - soybean oil meal; FM - fishmeal; 17 goats each; M. Hadjipanayiotou and A. Koumas (Agr. Res.Inst., Cyprus),
Small Rum. Res. 5(1991):319-326.
| Table 3. Effects of Forage to Concentrate Ratios on Milk Yield and Composition of Saanen-Marota Goats |
|
|
|
|
| Forage:Concentrate Ratio |
75:25
|
60:40
|
45:55
|
S.E.
|
| Milk yield, g/d |
469
|
480
|
582
|
157
|
| 4% FCM yield, g/d |
459
|
431
|
491
|
126
|
| Fat, % |
3.62
|
3.29
|
2.92*
|
0.48
|
| Protein, % |
3.4
|
3.90
|
3.73
|
0.42
|
| Weight change, g/d |
-50
|
-10
|
120
|
13
|
| Rumination, min/d |
363
|
339
|
299
|
40
|
| Eating, min/d |
207
|
214
|
188
|
30
|
| Chewing, min/g NDF/MW |
21.2
|
18.7
|
16.3*
|
1.8
|
9 goats each; J. R. Kawas et al. (EMBRAPA, Brazil), Small Rum. Res. 4(1991):11-18.
| Table 4. Average Milk Composition of Greek Native Goats |
|
|
|
| |
Range
|
Mean
|
S.D.
|
| Fat, % |
4.45-5.80
|
5.18
|
0.396
|
| Protein, % |
3.46-3.69
|
3.56
|
0.063
|
| Casein, % |
2.72-2.88
|
2.80
|
0.060
|
| Lactose, % |
4.39-5.02
|
4.74
|
0.181
|
| Total solids, % |
13.28-14.55
|
14.12
|
0.381
|
| SNF, % |
8.51-9.20
|
8.94
|
0.218
|
| Minerals, % |
0.69-0.82
|
0.76
|
0.037
|
| Ca, mg/100 ml |
128.48-152.16
|
141.11
|
5.741
|
| Mg, mg/100ml |
10.28-15.79
|
13.81
|
1.571
|
| Na, mg/100ml |
41.38-51.38
|
47.90
|
3.743
|
| K, mg/100ml |
156.41-168.77
|
161.65
|
4.423
|
| Acidity |
0.14-0.19
|
0.17
|
0.015
|
| pH |
6.32-6.68
|
6.55
|
0.068
|
| Density |
1.029-1.031
|
1.030
|
0.0002
|
164 goats; 40 bulk milk samples from March to Aug. after weaning; E. Simos et al.(Ioannina Dairy Res.Inst.,
Greece), Small Rum. Res. 4(1991):47-60.
J. Brun-Bellut et al. (INRA, France), Small Rum. Res. 3(1990):575-581.
| Table 6. Effects of Less Degradable Protein (Hydrolyzed Feathermeal) on Milk Yield and Composition of Alpine Goats |
|
|
|
| |
SBM
|
HFM
|
S.E.
|
| Degradable protein, % of total diet protein |
47.8
|
43.0
|
|
| Milk yield, kg/d |
3.20
|
3.16
|
0.32
|
| 4% FCM yield, kg/d |
2.72
|
2.66
|
0.60
|
| Fat, % |
3.0
|
3.0
|
0.2
|
| Fat, g/d |
96
|
93*
|
9
|
| Protein, % |
3.0
|
2.8
|
0.1
|
| Protein, g/d |
97
|
87*
|
7
|
| Casein, % |
2.68
|
2.49*
|
0.1
|
| Lactose, % |
3.2
|
2.9
|
0.3
|
| Total Solids, % |
10.0
|
9.4
|
0.3
|
SBM - soybean oil meal; HFM - hydrolysed feathermeal; 15 goats; C. D. Lu et al. (Langston Univ.), Small Rum.
Res. 3(1990):425-434.
| Table 7. Effects of Sodium Bicarbonate on Milk Yield and Composition of Damascus Goats |
|
|
|
| |
Control
|
+Bicarb
|
S.E.
|
| Milk yield, kg/d |
1.90
|
2.06
|
0.104
|
| 4% FCM, kg/d |
1.85
|
2.19**
|
0.100
|
| Fat, % |
3.9
|
4.5**
|
0.123
|
| Protein, % |
4.3
|
4.1**
|
0.068
|
| Minerals, % |
0.85
|
0.85
|
0.023
|
| Total solids, % |
13.0
|
13.3*
|
0.124
|
| Weight change, g/d |
11
|
26
|
45
|
18 goats each; M. Hadjipanayiotou (Agr. Res. Inst., Cyprus), Small Rum. Res. 1(1988):37-47.
| Table 8. Effect of Stage of Lactation on Average Composition of Alpine Goat Milk in Greece |
|
|
|
|
|
| |
Week of Lactation
|
| |
8-12
|
17-21
|
26-30
|
35-38
|
39-42
|
| Fat, % |
3.34
|
2.93
|
3.15
|
4.10
|
4.58
|
| Protein, % |
2.79
|
2.95
|
3.32
|
3.91
|
4.25
|
| Casein, % |
2.11
|
2.17
|
2.40
|
2.87
|
3.15
|
| Lactose, % |
4.46
|
4.42
|
4.35
|
4.08
|
3.96
|
| Minerals, % |
0.72
|
0.78
|
0.80
|
0.82
|
0.84
|
| Total solids, % |
11.17
|
10.98
|
11.54
|
12.78
|
13.47
|
| SNF, % |
7.83
|
8.05
|
8.39
|
8.68
|
8.89
|
| pH |
6.58
|
6.61
|
6.57
|
6.54
|
6.52
|
| Titrat. acidity |
16.60
|
16.30
|
16.65
|
17.38
|
17.44
|
| Density |
1.031
|
1.030
|
1.030
|
1.028
|
1.027
|
| Na, mg/100g |
50.20
|
52.20
|
54.00
|
54.75
|
55.50
|
| K, mg/100g |
170.40
|
166.00
|
155.20
|
146.75
|
144.50
|
| Na/K |
0.29
|
0.31
|
0.35
|
0.37
|
0.39
|
| Ca, mg/100g |
134.51
|
135.80
|
139.75
|
145.40
|
149.50
|
| P, mg/100g |
99.40
|
104.20
|
112.40
|
117.25
|
121.50
|
| Ca/P |
1.36
|
1.30
|
1.24
|
1.24
|
1.23
|
| Mg, mg/100g |
12.85
|
13.08
|
13.50
|
14.30
|
14.87
|
| Citrate, mg/100g |
145.42
|
114.50
|
99.64
|
88.23
|
81.17
|
42 goats; L. Voutsinas et al. (Ioannina Dairy Res.Inst., Greece), J. Dairy Res. 57(1990):41-51.
| Table 9. Comparative Mineral Composition of Milk From Cows, Sheep and Goats |
|
|
|
| |
Cow
|
Sheep
|
Goat
|
| Cu, mg/kg |
0.155*
|
0.411
|
0.404
|
| Fe, mg/kg |
0.441*
|
0.770*
|
0.666*
|
| Zn, mg/kg |
4.206*
|
5.660*
|
4.765*
|
| Mn, mg/kg |
0.026*
|
0.089*
|
0.155*
|
| Ca, mg/kg |
1199*
|
2056*
|
1552*
|
| Mg, mg/kg |
104.96*
|
193.53*
|
141.58*
|
| Na, mg/kg |
575.53*
|
509.51*
|
442.51*
|
| K, mg/kg |
1678*
|
1568*
|
1627*
|
10 samples from 440 Frisona cows; 10 samples from 20 Merino ewes; 10 samples from 145 Serrana-Andaluza goats
for 10 months each; F. Rincon et al. (Univ. Cordoba, Spain), J. Dairy Res. 61(1994):151-154.
| Table 10. Comparative Composition of Odorous Volatile Compounds in Milk of Cows, Sheep, Goats, and Water Buffaloes |
|
|
|
|
| |
Cow
|
Sheep
|
Goat
|
Buffalo
|
| Esters |
399
|
301
|
279
|
539
|
| Aldehydes |
96
|
127
|
88
|
154
|
| Ketones |
36
|
32
|
14
|
98
|
| Alcohols |
12
|
27
|
18
|
55
|
| S-compounds |
200
|
250
|
120
|
40
|
| Lactones |
1.7
|
1.5
|
0.9
|
0.5
|
| N-compounds |
41
|
132
|
83
|
139
|
| Aromatic compounds |
16
|
31
|
12
|
25
|
| Total |
802
|
901
|
615
|
1050
|
100 animal each; L. Moio et al.(Univ. Naples, Italy), J. Dairy Res. 60(1993):199-213.
| Table 11. Effects of bST on Milk Yield and Composition of Alpine and Saanen Goats |
|
|
|
|
|
|
| |
Week
|
|
| |
1
|
2
|
3
|
4
|
Mean
|
Control
|
| Milk yield, kg/d |
3.05
|
3.18
|
3.34
|
3.39
|
3.24
|
2.52**
|
| Fat, % |
2.28
|
2.68
|
2.76
|
2.95
|
2.79
|
2.52*
|
| Protein, % |
2.59
|
2.59
|
2.68
|
2.65
|
2.62
|
2.72*
|
| FA C6:0, g/100g |
|
|
|
|
2.41
|
2.29
|
| C8:0 |
|
|
|
|
2.66
|
2.56
|
| C10:0 |
|
|
|
|
10.92
|
10.29
|
| C12:0 |
|
|
|
|
5.72
|
5.45
|
| C14:0 |
|
|
|
|
12.57
|
12.51
|
| C14:1 |
|
|
|
|
1.51
|
1.90*
|
| C15:0 |
|
|
|
|
1.41
|
1.24*
|
| C16:0 |
|
|
|
|
35.42
|
35.58
|
| C16:1 |
|
|
|
|
1.11
|
1.35*
|
| C18:0 |
|
|
|
|
4.00
|
4.71
|
| C18:1 |
|
|
|
|
13.75
|
12.93
|
| C18:2 |
|
|
|
|
2.52
|
2.27
|
| Others |
|
|
|
|
3.94
|
4.74*
|
| C4:0-12:00 |
|
|
|
|
23.78
|
23.06
|
| C18:0-2 |
|
|
|
|
20.37
|
19.81
|
| Plasma |
|
|
|
|
|
|
| Urea, mg/L |
321
|
354
|
330
|
361
|
--
|
438*
|
| NEFA, microequ/L |
139
|
179
|
226
|
281
|
--
|
100*
|
| BHBA, mg/L |
39
|
36
|
36
|
40
|
--
|
33
|
| Glucose, mg/L |
558
|
467
|
487
|
476
|
--
|
499
|
5 goats each; C. Disenhaus et al. (INRA, France), Small Rum. Res. 15(1995):139-148.
| Table 12. Comparative Composition of Human and Goat Milk |
|
|
| |
Human
|
Goat
|
| Ca, mg/L |
280
|
1304
|
| P |
140
|
1080
|
| Mg |
35
|
136
|
| Na |
180
|
488
|
| K |
525
|
1996
|
| Cl |
420
|
1566
|
| Fe |
0.3
|
0.5
|
| Zn |
1.2
|
2.9
|
| Cu |
0.25
|
0.23
|
| Vitamin A (RE) |
670
|
548
|
| Vitamin D microg/L |
0.55
|
0.6
|
| Vitamin E |
2.3
|
--
|
| Vitamin K |
2.1
|
12
|
| Thiamin |
0.21
|
0.5
|
| Riboflavin |
0.35
|
1.4
|
| Niacin |
1.5
|
2.7
|
| Ascorbic acid |
40
|
12.6
|
| Panthothenic acid |
1.8
|
3.0
|
| Vitamin B6 |
0.093
|
0.5
|
| Vitamin B12 |
0.97
|
0.64
|
From NRC and USDA tables; D. L. O'Connor (Univ. Guelph, Canada), Small Rum. Res. 14(1994):143-149.
| Table 13. Protein Composition in Milk of Spanish Murciano-Granadina Goats as Affected by Days after Kidding |
|
|
|
| |
Days After Kidding
|
| |
85
|
160
|
210
|
| Protein, g/L |
37.00*
|
41.00*
|
43.96*
|
| Casein |
28.55*
|
32.36*
|
34.68*
|
| Whey protein |
8.44
|
8.63
|
9.29*
|
| Alpha-casein |
6.48*
|
8.66*
|
10.37*
|
| Beta-casein |
19.90*
|
21.28
|
21.42
|
| Kappa-casein |
2.25*
|
2.55
|
2.76
|
| Beta-lactoglobulin |
5.40*
|
5.76*
|
6.28*
|
| Alpha-lactalbumin |
1.23*
|
1.60*
|
1.77*
|
| Remainder whey protein |
1.79
|
1.26
|
1.22
|
44 goats each; A. Quiles et al. (Univ. Murcia, Spain), Small Rum. Res. 14(1994):67-72.
| Table 14. Effects of Meat Meal or Hydrolyzed Feather Plus Meat Meal on Yield, Composition and Cheese-Making Properties
of Alpine and Saanen Goat Milk |
|
|
| |
Meat Meal
|
Feather Meal Plus Meat Meal
|
| Milk yield, kg/d |
2.44
|
2.45
|
| Fat, % |
3.06
|
3.14
|
| Protein, % |
2.72
|
2.85*
|
| 3.5% FCM, kg/d |
2.28
|
2.31
|
| pH |
6.81
|
6.83
|
| Titratable acidity |
2.41
|
2.35
|
| Lactose, % |
5.00
|
4.92
|
| Casein, % |
1.84
|
1.95*
|
| Non-Casein N |
0.14
|
0.14
|
| Urea, mg/100 ml |
52.6
|
43.5
|
| Coagulation time, min. |
10.5
|
11.0
|
| Curd firmness rate, min. |
6.0
|
6.1
|
| Curd firmness at 45 min, mm |
29.4
|
29.6
|
| Weight change, g/d |
32
|
16
|
28 goats; I. Andrighetto and L. Bailoni (Univ. Padua, Italy), Small Rum. Res. 13(1994):127-132.
GM-9
04/97
|
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