Lipid Fractions and Fatty Acid Composition of Colostrums, Transitional and Mature She-Camel Milk During the First Month of Lactation
Azza M. Kamal
Omar A. Salama
Fatty acid composition, triglycerides, cholesterol and tocopherols were
determined in colostrums, transitional and mature milk. With progress
of lactation, triglycerides and percentage medium chain fatty acids increased
whereas tocopherols, cholesterol and percentage long chain polyunsaturated
fatty acids decreased. These changes reflect augmented de novo synthesis
of fatty acids (12:0, 14:0, 16:0 and 18:0) in the mammary gland and a
tendency of increasing fat globule size as milk matures. Transitional
and mature milks but particularly colostrums, contained higher concentrations
of components considered to be derived from the fat-globule membrane (cholesterol,
tocopherols, percentage long-chain polyunsaturated fatty acids). On the
same time, serum concentration of cholesterol, triglycerides, total lipids,
high density lipoprotein-cholesterol, low density lipoprotein and very
low density lipoprotein cholesterol were estimated and revealed a higher
level in older camel. Differences from data are discussed in relation
to analytical methods and possible consequences for lipid digestion, lipid
absorption, growth and brain development.
Studies on lipids and lipoproteins in domestic animals have made it clear that
species variations exist and that even within species significant differences
occur (Nazifi et al., 2000). Physical and chemical
properties of lipid dromedary camel milk were subject of many studies (Ali and
Omar, 2001; Farah, 1993; Abu-Leihia,
1989; Sawaya et al., 1984). The results showed
that camel milk lipids have a lower proportion of short chain fatty acids and
saturated fatty acids than cow milk.
With regard to macronutrients, the lipid fraction of milk seems to be of crucial
importance. Under normal conditions it does not only provide the main source
of energy but in addition contain fatty acids and fat-soluble vitamins that
are essential to sustain normal growth and brain development (Walker,
With progress of lactation, triglycerides and percentage medium-chain fatty
acids increased whereas α-tocopherols, cholesterol and percentage long-chain
polyunsaturated fatty acids decreased (Rudy et al.,
1991). These changes reflect augmented de novo synthesis of fatty
acids (8:0, 10:0, 12:0 and 14:0) in the mammary gland and a tendency of increasing
fat-globule size as milk matures (Rudy et al., 1991).
Transitional and mature milks, but particularly colostrums, contained higher
concentrations of components considered to be derived from the fat-globule membrane
(cholesterol, tochopherols, percentage long-chain polyunsaturated fatty acids)
compared with those reported for Western countries (Rudy
et al., 1991).
In this study we present the composition of the lipid fractions in colostrums,
transitional and mature camel milk. We measured the concentrations of
milk triglycerides, cholesterol and tocopherols and determined the fatty
acid concentration and composition of the total lipid fractions of milk.
Also the concentration of serum lipids and lipoproteins during the first
month of lactation were investigated and search to justify such dynamics
of changes in relation to the specific needs of growing neonates.
MATERIALS AND METHODS
Milk samples were collected from camels in Marsa Matrouh Farm (Animal
Production Institute, Dokki, Egypt) at varying stages of lactation, samples
were collected in the morning during winter. Samples (350 mL from each
camel) were collected in polyethelyne bottles and kept on ice during transportation
to the laboratory where they were stored at 30°C until analyzed. All
camels milk are taken during the 1st month of lactation at interval period,
we had delivered at term between 0 day and 5 day (colostrums), 6 day and
10 day (transitional) and the rest milk till 30 day (mature) milk.
All samples were taken with supervision by manual expression and were
collected in sterile containers without preservatives.Fatty acid standards
(as methyl esters) was obtained from Merck (Darmstadt, Germany) and triacylglycerols
standard from Reagent Laboratories (London, England).
Extraction of Camel Milk Lipids
Lipids were extracted four times from milk using the method of Rose-Gottlieb
as reported by (Pearson, 1976), using ammonia, methanol
and diethyl ether. Lipids were dried in a vacuum oven for 1 h at 45°C. Total
lipids were weighed after drying.
For the Stabilization of Tocopherols
Two hundred microliter sample was pipetted into a tube containing
0.5 mL antioxidant solution A (25 mmol potassium EDTA and 910 mmol vitamin
C L-1 water) and 1.3 mL antioxidant solution B (110 mmol pyrogallol
and 250 mmol butylated hydroxyl toluene L-1 methanol). The
remaining milk was put into plastic tubes. All tubes were capped and frozen
at -20°C until analyzed. When thawed, the contents of the tubes were
carefully mixed to ensure representative sampling.
Fatty Acid Methyl Esters
The fatty acid methyl esters of milk of samples were prepared by the procedure
of (Sheppard and Iverson, 1975). They were identified
by their retention time in comparison with standards and were expressed as percent
A Pye Unicam series 304 chromatography (Pye Unicam Ltd., UK) with flame
ionization detector was used to analyse the fatty acid methyl esters in using
10% polyethylene glycol adipate column (PEGA, 2.5 m lengh, 4 mm diameter). The
temperature of injector, column and detector were 190, 195 and 220°C, respectively.
Nitrogen served as a carrier gas at a flow rate of 60 mL min-1 while
the flow rates of hydrogen and air were 60 and 480 mL min-1, respectively.
This condition was achieved for separation of fatty acid of triacylglycerols
of camel milk and colostrums. The same results were obtained when we used temperature
programming. Starting column temperature was 140°C and final temperature
was 200°C with increase rate of 5°C per min (Steege
et al., 1987).
Cholesterol was determined by a separate capillary gas-chromatographic program
as previously described by (Muskiet et al., 1983).
The internal standard for quantification was 5β-cholestan-3α-ol.
Tocopherol was quantified by high-performance liquied chromatography with fluorescence
detection according to Lehman and Martin (1983) by using
tocol as an internal standared.
Triglycerides was quantified by gas liquid chromatography as previously described
by Stuart et al. (1968).
Blood samples were collected from the jugular vein at the same time
of milk collection. The serum was separated by centrifugation and stored
at 20°C until used.
Biochemical Analysis of Serum
||Cholesterol, triglycerides, total lipids were estimated
using commercial chemical reagent kits.
||HDL-cholesterol was measured by a precipitation method. In the first step,
the precipitation reagent (sodium phosphotungstate with magnesium chloride)
was added to the serum to aggregate non-HDL lipoproteins, which were sedimented
by centrifugation, then the residual cholesterol was measured by an enzymatic
method as described by Burtis and Ashwood (1994).
|| LDL cholesterol was calculated as the difference between cholesterol
in the precipitate and that in the HDL cholesterol.
||VLDL-cholesterol was estimated as one-fifth of concentration of triglycerides
(Friedewald et al., 1972).
Data were analysed by one-way ANOVA and regression analysis, using Spss/Pc
soft ware and Duncan`s multiple range test was used to detect significance differences
among the means (Norusis, 1993). All values were expressed
as mean±standard deviation with p≤ 0.05 being regarded as a significant
Relative saturated fatty acids content (Lauric acid (C12:0); Myristic
acid (C14:0) and Stearic acid (C18:0)), increased with duration of lactation
while Palmitic acid (C16:0) was decreased (Table 1).
The relative amount of the monounsaturated fatty acids (olic acid (C18:1)-ω-9)
was lower in mature than in transitional milk and colostrums. Among the
two parent essential Polyunsaturated fatty acids Linoleic acid (18:2)-ω-6,
was greater in transitional than in colostrums and in mature milk. While,
α-Linolenic (18:3)-ω-3 was low in transitional than in colostrums
and mature milk (Table 2).
Changes in percentages of fatty acids subgroups, As lactation progressed,
there is changes in the relative amounts of individual fatty acids, relative
saturated fatty acids content increased from colostrums till mature milk
and there is a rise in medium chain fatty acids, at the same time there
was a relative decline in long chain saturated fatty acid while, the relative
amount of the major polyunsaturated fatty acids was lower. Among the two
parent essential polyunsaturated fatty acids the percentage of linoleic
acid (18:2ω-6) was lower from colostrums till mature milk whereas
that of linolenic acid (18:3ω-3) was slightly higher from colostrums
to mature milk (Table 3).
||Changes in saturated fatty acid concentrations of camel`s
milk fat during the 1st month of lactation
|*Lauric acid show a significant increase in transitional
milk then continuous increase till reach mature milk. LSD at 0.05
between colostrums and mature milk = 0.95; **Myristic acid show a
significant increase in transitional milk and continuous increase
till reach mature milk. LSD at 0.05 between colostrums and mature
milk = 2.15; ***Palmitic acid show a significant decrease from colostrums
till reach mature milk. LSD at 0.05 between colostrums and mature
milk = 3.10; ****In Stearic acid, there is an increase till reach
transitional milk then decrease again in mature milk. LSD between
colostrums and transitional milk = 1.52
||Changes in polyunsaturated fatty acid concentrations of camel`s
milk fat during the 1st month of lactation
|***Olic acid there is a significant decrease from colostrums
till transitional milk and then continuous decrease till mature milk.
LSD at 0.05 between colostrums and mature milk = 7.50; **In Linoleic
acid show a significant increase from colostrums till reach transitional
milk and return decrease till reach mature milk. LSD at 0.05 between
colostrums and transitional milk = 1.12; *α-Linolenic there is
a slightly decrease from colostrums till transitional milk then increased
again in case of mature milk
|| Composition (g/100 g) of main fatty acid subgroups in colostrums,
transitional and mature milk samples of camel`s milk
|***: Highly significant increase in mature milk in case
of SAFAs (saturated fatty acids) and MCFAs (medium chain fatty acids)
but decrease in LCFAs (long chain fatty acids) and PUFAs (polyunsaturated
fatty acids) than in colostrums. Omega 6 show: Significant decrease
but omega 3 show: Significant increase in mature milk, **: Moderate
||Concentrations of triglycerides, total cholesterol and α-tocopherol
in camel`s milk during the 1st month of lactation
|***: Highly significant increase in mature milk in case of
triglycerides but decrease in cholesterol and α-tocopherol in mature
milk than in colostrums; The ratio of cholesterol to triglycerides = 7.42
in colostrums and 1.37 in mature milk
||Concentrations of total cholesterol, triglycerides, total
lipid, High Density Lipoprotein (HDL), Low Density Lipoprotein (LDL) and
Very Low Density Lipoprotein (VLDL) cholesterol in camels serum during the
1st month of lactation
|*: Slight increase in mature milk than in colostrum
A significant increase in concentration of triglycerides in mature milk than
in colostrums but free cholesterol and α-tocopherol show a significant
decrease in mature milk than colostrums (Table 4).
On the same time, an increase on serum concentration in cholesterol, triglycerides,
total lipids, high density lipoprotein-cholesterol, low density lipoprotein
and very low density lipoprotein cholesterol in older animals (Table
Total Fatty Acid Composition
Data presented in Table 1 and 3 show
that, mature milk had higher amounts of saturated fatty acids than colostrums
as a result of elevated levels of 12:0-14:0 and 16:0 fatty acids in milk, this
results are similar to Ali and Omar (2001). Even numbered saturated fatty acids
14:0-16:0-18:0 in camel milk lipid consider as the major components of total
fatty acids. The presence of medium-chain fatty acids in camel milk could indicate
their synthesis in the mammary gland. These results are similar to those reported
by Ali and Omar (2001), Abou-Lehia (1989) and Sawaya
et al. (1984). Camels are capable of producing these saturated fatty
acids by cellulose fermentation in the rumen (Ali and Omar, 2001; Kurtz,
Koiter et al. (1989) revealed that, increased
de novo synthesis of MCFAs (12:0-14:0) by the lactating cell implies
an enhanced flux of glucose over the basal plasma membrane, this may be induced
by an augmented responsiveness of the mammary gland to insulin after gestation,
which may be due to an increasing number of insulin receptors on the mammary
gland. These saturated fatty acids constitute an energy source that is independent
from bile acids for its absorption (Thomposon et al.,
1985; Bach and Babayan, 1982; Insull,
1965). Ingestion of large amount of MCFAs (by neonate) induces excessive
β-oxidation and subsequently a superfluous synthesis of ketone bodies (Mortensen
and Gregersen, 1980). As a consequence, MCFAs may become ω-oxidized
which eventually leads to a waste of energy-rich dicarboxylic acids. Furthermore,
a relatively high energy intake from MCFAs may enhance the absorption of calcium,
magnesium (Tantibhedhyangkul and Hashim, 1978) and amino
acids (Holtzapple et al., 1972). All these factors
may contribute to an increased speed of growth during the first month of life.
This result are similar to those of dromedary camel milk reported by Zhang
et al. (2005), Gorban and Izzeldin (2001),
Abu-Lehia (1989) and Sawaya et
The major polyunsaturated fatty acids were 18:1, 18:2 and 18:3 (Table
2 and 3). The unsaturated fatty acids of colostrums
18:1 was higher than the corresponding milk values and this could account
for the higher total unsaturated fatty acids in triacylglycerols of the
colostrums when compared to that milk, this result agree with Ali and
Omar (2001). 18:2 and 18:3 increase in colostrums which decrease lipogenesis
and esterification, Also it increase oxidation of fatty acids
in liver and increase gluconeogenesis in ruminant hepatocytes
which help in growing neonates.
According to Gnan and Sheriha (1986), camel`s milk fat
contained high levels of polyunsaturated fatty acids and factors that affect
the fatty acids composition of camel milk include breed, feeding, composition
of dietary fat, dietary protein, seasonality and region and stage of lactation
(Gorban and Izzeldin, 2001; Palmquist
et al., 1993). This result agree with Zhang et
al. (2005) and Ali and Omar (2001).
Lipid Classes and Fat Globules
Results of present study, show notable changes in lipid fractions of milk
with duration of lactation, this result agree with Gorban and Izzeldin (1999)
and Ali and Omar (2001). Triglyceride concentrations were lower in colostrums
than in mature milk, which coincided with a decrease of cholesterol and the
percentage of LC PUFAs (ω3 andω6) (Table 4). As a
consequence, the ratio of cholesterol to triglycerides = 7.42 in colostrums
and 1.37 in mature milk. The core of the fat globule in milk is mainly comprised
of triglyceride whereas its membrane contains the majority of milk cholesterol
and phospholipids, the latter contain an abundance of long chain polyunsaturated
fatty acids, which useful for the growth of the neonates (Ali and Omar, 2001;
Muskiet et al., 1988; Harzer
et al., 1983; Ruegg and Blanc, 1981).
While, cholesterol and tocopherol were increased in colostrums than in mature
milk in present study, this result was similar to that reported by Rudy
et al. (1991). Assuming that the vast majority of vitamin E is secreted
as a constituent of the fat-globule membrane, a decline of the vitamin E in
mature than in colostrums milk may further support this concept. Another explanation
is a higher contribution of constituents from white cell membranes during early
lactation (Rudy et al., 1991).
Serum Lipid and Lipoprotein Profile
Age had a significant effect on the serum concentration of cholesterol,
triglycerides, total lipids, high density lipoprotein-cholesterol and very low
density lipoprotein cholesterol of camel (Table 5) the values
were being higher in older animals. The concentration of serum cholesterol of
present study was similar to the values reported by Nazifi
et al. (2000), Al-Ani et al. (1992)
and Wasfi et al. (1987). It was lower than the
values reported for cows, sheep goats and Ilamas (Kaneko, 1989).
The concentration of triglyceride in the serum of present study was lower than
the value reported by Nazifi et al. (2000) but
similar than the result reported by Wasfi et al. (1987).
The concentration of lipoprotein (HDL, LDL and VLDL) in the serum of present
study is similar to the result of Nazifi et al. (2000)
in Iranian male dromedary.
Braemwald (1995) and Kleinveld (1996)
reported that in human, there was a slight increase in the concentrations of
serum cholesterol and triglycerides in advanced age (Noro
et al., 1993) found a high concentration of low density lipoprotein
and a low concentration of high density lipoprotein in calves immediately after
birth. By 6 days of age, low density lipoprotein concentration had decreased
and the high density lipoprotein concentration had increased to the levels found
in adult animals (Noguchi, 1993) reported that, in humans,
the concentrations of low density lipoprotein and very low density lipoprotein
increased and the concentration of high density lipoprotein decreased with increasing
age (Hugi and Blum, 1997) reported that, in calves the
concentration of serum cholesterol increased transiently with age, but serum
triglycerides did not show a consistent change.
In this study, significant correlations were observed between the serum
cholesterol and the triglycerides and various lipoproteins.
Present data indicate that changes occurring in camel milk during the 1st month
of lactation is a useful nutritional attribute since saturated fatty acids are
rapidly metabolized by camel tissue before they have a chance to be excreted
in the milk and constitute an energy source and induces excessive β-oxidation
and subsequently a superfluous synthesis of ketone bodies and may enhance the
absorption of calcium, magnesium and amino acids. Also, it appears that biohydrogenation
of polyunsaturated fatty acids is less extensive in the rumen of the camel and
polyunsaturated fatty acids was high in colostrums of camel milk, All these
factors may contribute to be the specific needs of growing neonates and increased
speed of growth during the first month of life.
In addition, the study show that age had a significant effect on serum
concentration of cholesterol, triglycerides, total lipids, high density
lipoprotein-cholesterol and very low density lipoprotein cholesterol of
camel, the values being higher in older animals.
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