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Milk and Meat Products
Composition Of Goat Milk And Factors Affecting It
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).
16 goats each; A. Baldi et al. (Univ. Milano, Italy), Small Rum. Res. 6(1992):303-310.
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.
9 goats each; J. R. Kawas et al. (EMBRAPA, Brazil), Small Rum. Res. 4(1991):11-18.
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.
SBM - soybean oil meal; HFM - hydrolysed feathermeal; 15 goats; C. D. Lu et al. (Langston Univ.), Small Rum. Res. 3(1990):425-434.
18 goats each; M. Hadjipanayiotou (Agr. Res. Inst., Cyprus), Small Rum. Res. 1(1988):37-47.
42 goats; L. Voutsinas et al. (Ioannina Dairy Res.Inst., Greece), J. Dairy Res. 57(1990):41-51.
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.
100 animal each; L. Moio et al.(Univ. Naples, Italy), J. Dairy Res. 60(1993):199-213.
5 goats each; C. Disenhaus et al. (INRA, France), Small Rum. Res. 15(1995):139-148.
From NRC and USDA tables; D. L. O'Connor (Univ. Guelph, Canada), Small Rum. Res. 14(1994):143-149.
44 goats each; A. Quiles et al. (Univ. Murcia, Spain), Small Rum. Res. 14(1994):67-72.
28 goats; I. Andrighetto and L. Bailoni (Univ. Padua, Italy), Small Rum. Res. 13(1994):127-132.