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Composition Of Goat Milk And Factors Affecting It
By George Haenlein
Oct 28, 2002, 11:22am

http://ag.udel.edu/extension/information/goatmgt/gm-09.htm

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.


Table 5. Effects of Rumen-Degradable Protein on Milk Yield of Alpine Goats
Control Formaldehyde Treatment F
Goats 10 10
RDP, % DM 7.2 5.1
Milk yield, kg/d 2.44 2.01 1.36
Milk urea, mg/L 262 204 18.4**
Goats 15 15 15
RDP, %DM 9.7 8.2 6.7
3.5% FCM yield, kg/d 2.57 2.53 2.54 0.01
Milk urea, mg/L 387 313 226 87.7**

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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