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Global J Res. Med. Plants & Indigen. Med. | Volume 3, Issue 11 | November 2014 | 389–401

Global Journal of Research on Medicinal Plants & Indigenous Medicine || GJRMI ||

ISSN 2277-4289 | www.gjrmi.com | International, Peer reviewed, Open access, Monthly Online Journal

EVALUATION OF THE BIOCHEMICAL AND HEMATOLOGICAL

PARAMETERS IN THE SERUM OF ALBINO RATS FED WITH

SKIMMED, WHOLE, FLAVORED AND SOYA MILK

COMMONLY CONSUMED IN NIGERIA

Essien E B1*, Onwuka F C

2, Odjoh O

3, Odeghe O B

4

1,2,3,4

Department of Biochemistry, Faculty of Science, P.M.B 5323 University of Port Harcourt, Rivers State,

Nigeria.

*Corresponding Author: E-mail: [email protected]

Received: 07/08/2014; Revised: 20/10/2014; Accepted: 30/10/2014

ABSTRACT

The effect of milk samples on haematological and biochemical parameters in the serum of twenty-

five albino rats was evaluated. Rats were subjected to feeding trial over a period of 4 weeks on diets

containing: 100g of standard rat feed and water (group A), 55g of milk sample with 45g of standard rat

feed and water for groups B (skimmed milk), C (whole milk), D (soya milk), and E (flavoured milk). At

the end of the experimental period, the highest weight gain was observed in rats fed with soya milk

(61.20%), while rats fed with skimmed milk had the least weight gain (32.40%) when compared to the

control (47.80%). Rats fed with soya milk had the highest hemoglobin concentration (13.24 ± 0.42g/dl)

and packed cell volume (39.80 ± 1.28%). The urea concentration of rats fed with soya milk was higher

(3.10 ± 0.05 mmol/l) than values obtained from the other milk samples evaluated. Results of creatinine

and bilirubin concentrations of rats in all groups were within normal values, while the values obtained

from the enzyme activities analyzed were consistent with normal reference values. Rats fed with

skimmed milk had the highest cholesterol and high density lipoprotein cholesterol concentrations as 3.70

± 0.05mmol/l and 0.91 ± 0.00mmol/l respectively, when compared to the control (3.23 ± 0.03 and

0.83 ± 0.01mmol/l respectively). A hypocholesteremic effect was observed in rats fed with whole milk,

soya milk and flavoured milk. Rats fed with flavoured milk and skimmed milk had higher concentration

of low density lipoprotein cholesterol (2.03 ± 0.61mmol/l and 2.33 ± 0.06mmol/l respectively) when

compared to the control group (1.96 ± 0.03mmol/l). The least triglyceride concentration was observed in

rats fed with soya milk (1.06 ± 0.08mmol/l) when compared to the control, while rats fed with skimmed

milk, whole milk and flavored milk had elevated triglyceride levels. Results of present investigation

demonstrate the benefits of consuming soya milk. On the other hand, the consumption of skimmed milk

with respect to weight gain is encouraged.

KEY WORDS: Milk, biochemical, hematological, enzyme activities, blood lipids.

Research Article

Cite this article:

Essien E B, Onwuka F C, Odjoh O, Odeghe O B (2014), EVALUATION OF THE BIOCHEMICAL AND

HEMATOLOGICAL PARAMETERS IN THE SERUM OF ALBINO RATS FED WITH SKIMMED,

WHOLE, FLAVORED, AND SOYA MILK COMMONLY CONSUMED IN NIGERIA,

Global J Res. Med. Plants & Indigen. Med., Volume 3(11): 389–401



INTRODUCTION

Milk is the natural secretion of the

mammary glands which plays a fundamental

role in nutrition, growth, development and

immunity of the newly born young (Woo et al.,

1995). Each species of mammals produces

milk with a unique composition designed to

meet the specific needs of the infants. For

instance, the milk of animals that grow rapidly,

such as cows which double their birth weight in

50 days is rich in protein and minerals. Milk

has also been defined as an emulsion of fat

globules in a suspension of casein micelles, all

suspended in an aqueous phase which contains

solubilized lactose, whey proteins and mineral

salts (Jensen, 1998). Milk is a highly nutritious

versatile food. People enjoy drinking milk in its

natural form and also use it to make a wide

range of food products including butter, yogurt,

cheese and ice cream. Cow’s milk and milk

products have played an important role in

human nutrition. Fresh cow milk is reported to

contain about 88% water (Kataoka et al.,

1991). During processing, the water content of

the milk is reduced, which confers desirable

qualities on the milk such as increased shelf

life, product flexibility and decreased

transportation cost (Miller et al., 1999). Milk

and milk products play an important part in a

healthy diet as they contribute to intakes of

essential nutrients and protein of a nutritionally

high quality. Milk products provide beneficial

nutrients including calcium, riboflavin, protein

and vitamin A to the diet (Block, 1985), but

whole milk products also contribute significant

amount of fats, saturated fat and cholesterol,

which have been shown to increase blood

cholesterol and subsequently pose a risk of

coronary heart disease (Kristi et al., 1994).

Several investigations on the effect of milk

in relation to coronary heart diseases have been

carried out on both rats and man. While some

investigations reveal the benefits of milk

consumption, other studies have established a

link of the dairy product to coronary heart

disease. Still, some other researchers have

encouraged the consumption of specific milk

brands due to results obtained from their

findings. But there was no convincing evidence

that milk is harmful (Elwood et al., 2004).

Another study found no evidence that men

(aged 35–64 years) who consumed milk each

day, at a time when most milk consumed was

full fat milk, were at increased risk of death

from all causes or from coronary heart disease

(Ness et al., 2001). On the contrary, another

study has shown a high positive correlation

between milk consumption in different

countries and rates of death a few years later

from coronary heart disease (Margaret, 2002).

Milk intake is probably positively related to

blood lipids (Steinmetz et al., 1994). Although

milk has long been considered an important

factor in coronary heart disease because of the

contribution it makes to the dietary intake of

saturated fats, expert groups have advised that

milk consumption should be limited, and that

fat reduced milk should be preferred

(Nutritional Aspects of Cardiovascular Disease,

1994). This fact was further strengthened in a

report by Kritchevsky et al. (1979), in which

they pointed out that there is a factor in milk

which helps to reduce cholesterol levels in rats

and man. Although the mechanism by which

milk help to reduce cholesterol level is unclear,

they suggest that milk does not exert a

hypercholesterolemic effect. A study on eight

healthy male subjects (adults) demonstrated the

benefits of drinking skimmed milk, as

compared with whole milk (Kristi et al., 1994).

As a result of the effects of milk on human

health, some individuals now consume soya

milk in place of dairy milk products. Using soy

milk to replace foods high in animal protein

that contain saturated fat and cholesterol may

confer benefits to cardiovascular health (Sacks

et al., 2006). Comparative clinical trials have

shown that consumption of diets rich in soy

protein as opposed to those high in animal

protein significantly lowered blood total

cholesterol, low density lipoprotein, and

triglycerides, without lowering helpful high

density lipoprotein cholesterol (Anderson et al.,

1995). As a result of the previous research

investigations on the effect of milk on coronary

heart diseases examined, the present study was

carried out with a view of bringing to light the

effect of milk consumption on the



hematological and biochemical parameters in

the serum of albino rats.

MATERIALS AND METHODS

Collection and preparation of milk samples

The different types of milk used for this study

were purchased from a local market in Choba,

Port Harcourt. Dano slim milk serve as

skimmed milk, cowbell chocolate flavor milk

as flavoured milk, while peak instant full cream

milk powder as the whole milk used for this

study. Soya bean seed (Glycine maximus) were

bought from a local market, cleaned off dirt and

soaked with clean water for 12 hours. It was

thereafter hulled, washed, and ground to a

homogenous paste. To this was added water to

form a slightly liquid mixture and filtered with

cheese cloth to obtain the filtrate as milk which

was analyzed immediately.

Experimental design

Twenty-five albino rats (Wistar strain)

weighing between 182–247g were purchased

from the Animal House of the Department of

Biochemistry, University of Port Harcourt. The

animals were then divided into five groups of

five rats each designated A (control), B, C, D,

and E. Before the commencement of the dietary

regimen, the animals were fasted over night but

allowed access to water ad libitum. The

treatment protocol is as follows: group A

received 100 g of standard rat feed and water,

groups B, C, D, and E were fed 55 g of

skimmed, whole, soya, and flavoured milk

respectively with 45 g of standard rat feed.

Assay

At the end of the study period, the animals

were exposed to chloroform vapour, and about

2ml of blood sample was obtained by cardiac

puncture, which was transferred into EDTA

and heparin bottles. Blood samples were then

centrifuged at 4000 rpm for 10 minutes to

obtain serum, which was stored in the

refrigerator and analyzed three hours later. The

weights of the animals were taken before and

after the dietary regimen. The proximate

analysis was determined using the standard

method of AOAC (1984). These include the

determination of crude protein, crude fat,

moisture content, ash, crude fiber,

carbohydrates and minerals, while the

phytochemical screening of the secondary

metabolites in soya milk was by the method of

Harborne (1973). The vitamin contents were

analyzed according to the method of AOVC

(1966). The energy content was obtained by

multiplying the protein, fat and carbohydrates

by factors 4, 9 and 4 respectively.

Haematological parameters were analyzed

using microhaematocrit method and Sahli’s

haemoglobinometer as described by Ramnik,

1990. The biochemical parameters analyzed

was carried out using commercial kits from

Randox laboratories Ltd (Northern Ireland).

Total protein was determined by the Biuret

reaction described by Tietz (1990) and albumin

concentrations were estimated by method of

Doumas et al. (1971). Creatinine estimation

was done using Reflotron, a semi automated

dry chemistry analyzer, and urea was by the

method of Fawcett and Scott, (1960). Bilirubin

concentration was by the method of Jendrassik

and Grof, (1938). Serum samples were

analyzed for aspartate aminotransaminase

(AST), alanine aminotransaminase (ALT), and

alkaline phosphatase activities using

commercial kits as described by Reitman and

Frankel (1957), and Klein et al. (1960).

Determination of total cholesterol in the serum

was by the method of Trinder, (1960); high

density lipoprotein cholesterol (HDL-C) was

determined by the method of Friedewald

(1972), while the level of low density

lipoprotein cholesterol (LDL-C) was calculated

using Friedewald’s equation. Serum

triglyceride (TG) was determined using the

method of Tietz, (1990).

Statistical analysis

The data were analyzed using inferential

statistics. All values are presented as Mean ±

SEM (standard error of mean) for 5 rats in each

of the 5 groups. The significance of difference

in the means of all parameters reported was



determined using one way ANOVA by least

significant difference (LSD) comparison test.

RESULTS

Results of the study to evaluate the

proximate composition, biochemical and

hematological parameter in the serum of albino

rats fed with skimmed milk, whole milk, soya

milk and flavoured milk are presented in tables

1 to 7. The result of proximate analysis of milk

samples is presented in Table 1. The milk

samples had energy values of between

261.5kcal and 393.2kcal. Whole milk had the

highest energy value while skimmed milk had

the least energy value. The highest crude

protein obtained was recorded in skimmed milk

(28.13%), followed by whole milk (24.01%),

and soya milk (21.44%), with flavoured milk

having the least crude protein value of 12.36%.

The ash content was highest in skimmed milk

(8.70%), with the least value in flavoured milk

(2.13%). Although whole milk had the highest

fat content of 23.16% than the other milk

samples, it had the least moisture content

(0.81%), while skimmed milk had the least fat

content (2.52%). The fiber content of the milk

samples range between 0 and 36.62%, with

soya milk having the highest fiber content.

Flavoured milk had the highest carbohydrate

content of 56.44%, while the least carbohydrate

content was obtained from soya milk. The

vitamin and mineral contents of whole and

flavoured milk were reported as stated by the

manufacturers, while the trace elements in

skimmed milk were analyzed. The proximate

composition of soya milk was obtained by

analysis. The highest of vitamin B1 was

observed in whole milk (0.99 mg), with soya

milk obtaining the least value (0.19mg).

Skimmed and flavoured milk both had the

highest content of vitamin B2, being 1.40 mg

respectively, while soya milk had the least

vitamin B2. Although soya milk had the highest

vitamins B6 and B12 values of 5.35 mg and 3.47

mg, than the other milk samples, it obtained a

corresponding least vitamin C content (3.63

mg), with whole milk had the highest vitamin C

content. Results of macro and trace minerals

obtained revealed skimmed milk as having the

highest content of calcium (1800 mg),

phosphorus (900 mg), and potassium (1600

mg), with soya milk had the least calcium (81.5

mg), phosphorus (5.50 mg), and potassium (12

mg) contents. The magnesium content was

higher in soya milk (192.69 mg), and least in

whole milk (85 mg). The iron content range

between 0.17 and 15.30 mg, with the highest

value obtained from soya milk and whole milk

having the least value. The zinc content of

whole milk was higher than the other milk

samples analysed. Results of phytochemical

screening of soya milk indicate the presence of

glycosides, steroids, terpenoids, and reducing

sugars (Table 2).

The initial and final body weights of rats

fed with milk samples are presented in Table 3.

An increase in body weight was observed in

each group at the end of the dietary regimen.

However, there was no significant difference in

the initial and final body weights of the control

and treatment group. Rats fed with soya milk

(61.20%) gained the highest weight when

compared with the control group (47.80%),

while the least weight gained was observed in

rat groups fed with skimmed milk (32.40%).

The hematological investigation on rats fed

the milk samples is presented in Table 4. Group

D rats fed soya milk had the highest

hemoglobin concentration (13.24 ± 0.42g/dl)

and packed cell volume of 39.80 ± 1.28%,

while the least values was obtained from the

control group (10.04 ± 0.98 g/dl and

30.00 ± 2.94%) respectively. No significant

difference was observed in the hemoglobin

concentration of groups B, C and E rats (fed

with skimmed, whole, and flavoured milk

respectively) when compared with the control,

while a significant difference was observed in

the packed cell volume of groups B and E rats

when compared with the control group.



Table 1. Proximate analysis of milk samples and soya milk analyzed

Parameter Skimmed milk whole milk Flavoured milk Soya milk

Energy (kcal) 261.5 393.2 339.2 339.2

Protein (%) 28.13 ± 0.15 24.01 ± 0.03 12.36 ± 0.64 21.44 ± 0.29

Ash (%) 8.70 ± 0.01 5.44 ± 0.03 2.13 ± 0.13 6.50 ± 0.02

Fats (%) 2.52 ± 0.08 23.16 ± 0.23 7.11 ± 0.20 21.90 ± 0.42

Moisture (%) 3.96 ± 0.03 0.81 ± 0.01 21.52 ± 0.57 1.20 ± 0.01

Fiber (%) 0.00 0.00 0.00 36.62 ± 0.03

Carbohydrate (%) 31.57 ± 0.82 22.21 ± 0.03 56.44 ± 2.23 12.34 ± 0.17

Vitamin A (IU) 2500* 2700 3750 23.21 ± 0.02

Vitamin B1(mg) NI 0.99 0.90 0.19 ± 0.02

Vitamin B2 (mg) 1.40 1.10 1.40 0.15 ± 0.03

Vitamin B3 (mg) NI 0.60 11.00 0.98 ± 0.08

Vitamin B6 (mg) NI 0.90 1.50 5.35 ± 0.04

Vitamin B12(mg) 0.003 0.0024 0.0045 3.47 ± 0.07

Vitamin C (mg) NI 90 30 3.63 ± 0.03

Vitamin E (mg) NI 0.60 4.00 0.34 ± 0.05

Calcium (mg) 1800 930 380 81.5 ± 0.06

Phosphorus (mg) 900 750 312 5.50 ± 0.02

Magnesium (mg) 120 85 121 192.69 ± 0.07

Potassium (mg) 1600 1200 523 12.00 ± 0.06

Sodium (mg) 19.87 340 106 2.59 ± 0.11

Iron (mg) NI 0.17 13.50 15.30 ± 0.06

Zinc (mg) 0.08 31 3.8 0.20 ± 0.03

Copper (mg) 0.12 0.02 0.1 0.20 ± 0.03

Selenium (µg) NI 10 17.5 7.15 ± 0.02mg

Manganese (mg) 0.04 0.02 0.10 0.01 ± 0.02 *Enriched, NI= Not indicated

Table 2. Phytochemical Screening Of Soya Milk

Secondary metabolites Relative abundance

Alkaloids −

Flavonoids −

Glycosides ++

Saponins ND

Steroids ++

Terpenioids +++

Carbohydrates ND

Reducing sugar ++

Resin ND

Tannins −

Proteins ND

Oils ND

Acid compounds ND Key: − = Absent; + = Low in concentration; ++ = Moderate in concentration; +++ = High in concentration;

ND = Not determined



Table 3. Mean body weights of rats (grams) fed the milk samples

Groups Initial body weight Final body weight Weight gained (%)

Control 218.20 ± 12.31b 266.00 ± 14.50

b 47.80

Skimmed milk 208.00 ± 9.43b 240.40 ± 12.25

b 32.40

Whole milk 206.60 ± 6.79b 242.20 ± 7.45

b 35.60

Soya milk 209.80 ± 10.05b 271.00 ± 10.95

b 61.20

Flavoured milk 209.60 ± 8.61b 245.60 ± 9.26

b 36.00

Values are mean ± SEM (n=5/group). bP>0.05. One way ANOVA by least significant difference comparison (LSD) test

Table 4. Hematological parameters of rats fed with milk samples

Group Hemoglobin (g/dl) Packed cell volume (%)

Control 10.04 ± 0.98b 30.00 ± 2.94

b

Skimmed milk 11.22 ± 0.44b 33.60 ± 1.20

a

Whole milk 10.47 ± 0.77b 31.50 ± 2.32

b

Soya milk 13.24 ± 0.42a 39.80 ± 1.28

a

Flavoured milk 11.50 ± 0.16b 34.80 ± 0.37

a

Values are mean ± SEM (n=5 rats/group). Values in the same row carrying different superscripts are significantly

different (P<0.05).

The results obtained for the biochemical

parameters considered in this study is presented

in Table 5. The control rats had the highest

serum total protein concentration being 67.40 ±

0.86g/l, while animals fed soya milk had the

least total protein concentration of 44.73 ±

4.78g/l. The least albumin concentration was

obtained by rats fed with soymilk (27.13 ±

2.70g/l), followed by rats fed with flavoured

milk (31.13 ± 2.54g/l) and whole milk (31.70 ±

3.09g/l) respectively. The control group had the

highest albumin concentration as 40.20 ±

0.49g/l, followed by rats fed with skimmed

milk (39.40 ± 0.00g/l). Although no significant

difference was observed in serum creatinine,

urea and bilirubin concentration of rats in each

groups, the creatinine concentration ranged

from 57.33 ± 0.66 to 60.66 ± 0.33µmol/l. Rats

fed with flavoured milk had the least creatinine

concentration, with the highest concentration

observed in rats fed with soya milk. Rats fed

with soya milk had the highest urea

concentration of 3.10 ± 0.05 when compared

with the control rats (2.90 ± 0.10), with the

least value obtained by rats fed with flavoured

milk (2.80 ± 0.05mmol/l). A slight significant

increase in urea concentration was observed in

rats fed with skimmed milk and whole milk

when compared to the control group, while rats

fed flavoured milk had slight reduction as

compared to the control group. The direct

bilirubin concentrations of rats ranged between

3.26 ± 0.14 µmol/l (soya milk) and 4.00 ±

0.57µmol/l (whole milk). The control rats

obtained the highest total bilirubin

concentration being 7.53 ± 0.37µmol/l,

followed by rats fed with soya milk (7.26 ±

0.21µmol/l), while rats fed with whole milk

had the least total bilirubin concentration (6.96

± 0.32µmol/l).

The enzyme activities of animals fed the

various experimental diets and the control is

depicted in Table 6. From the results obtained,

no significant difference (P>0.05) was

observed in the activities of aspartate

aminotransaminase (AST), alanine

aminotransminase (ALT) and alkaline

phosphatase when compared with the values

obtained from the control rats.

The effect of the various milk samples on

serum lipid profile of rats is shown in Table 7.

From the results obtained, the highest

cholesterol level was obtained by rats fed

skimmed milk being 3.70 ± 0.05mmol/l, while

rats fed whole milk had the least cholesterol

value (1.76 ± 0.08 mmol/l). A significant

reduction in the cholesterol level of rats fed



with whole milk, soya milk and flavoured milk

was observed when compared with the control

group (3.23 ± 0.03mmol/l). The high density

lipoprotein cholesterol levels of rats had values

of between 0.47 ± 0.03 and 0.91 ± 0.00mmol/l.

Although no significant difference in the high

density lipoprotein cholesterol levels of both

the control and treatment groups was observed,

rats fed with skimmed milk had the highest

high density lipoprotein cholesterol value with

the least value obtained by rats fed with whole

milk. The low density lipoprotein cholesterol of

the rats had values between 0.77 ± 0.08 and

2.33 ± 0.06 mmol/l. The highest value was

obtained from rats fed with skimmed milk, with

rats fed with whole milk having the least value.

The triglyceride concentration in the test and

non-test groups had values between 1.06 ± 0.08

and 2.43 ± 0.12mmol/l. The highest triglyceride

value was obtained by rats fed whole milk,

while rats fed with soya milk had the least

value. A significant increase in triglyceride

concentration of rats fed with skimmed and

whole milk was observed when compared with

the control group (1.73 ± 0.03mmol/l), with

rats fed with soya and flavoured milk showing

a significant decrease.

Table 5. Serum concentrations of the biochemical parameters analyzed.

Parameter Control

Skimmed

milk

Whole milk Soya milk Flavoured

milk

Total protein (g/l) 67.40 ± 0 .86b 65.40 ± 0.29

b 52.83 ± 5.13

a 44.73 ± 4.78

a 55.23 ± 4.76

a

Albumin (g/l) 40.20 ± 0.49b 39.40 ± 0.00

b 31.70 ± 3.09

a 27.13 ± 2.70

a 31.13 ± 2.54

a

Creatinine (µmol/l) 58.00 ± 2.00b 59.33 ± 1.76

b 59.33 ± 0.66

b 60.66 ± 0.33

b 57.33 ± 0.66

b

Urea (mmol/l) 2.90 ± 0.10b 2.96 ± 0.08

b 2.96 ± 0.03

b 3.10 ± 0.05

b 2.80 ± 0.05

b

Direct bilirubin

(µmol/l)

3.66 ± 0.24b 3.93 ± 0.06

b 4.00 ± 0.57

b 3.26 ± 0.14

b 3.70 ± 0.35

b

Total bilirubin

(µmol/l)

7.53 ± 0.37b 6.70 ± 0.20

b 6.96 ± 0.32

b 7.26 ± 0.21

b 6.73 ± 0.83

b

Values are mean ± SEM (n=5). Values in the same row carrying different superscripts are significantly different

(P<0.05).

Table 6. Serum activities of enzymes studied (U/L)

Parameter

Control Skimmed

milk


milk

Aspartate

aminotransaminase

5.90 ± 0.05b 5.66 ± 0.33

b 6.00 ± 0.57

b 6.03 ± 0.03

b 5.86 ± 0.13

b

Alanine

aminotransaminase

6.10 ± 0.05b 6.00 ± 0.57

b 6.00 ± 0.00

b 5.30 ± 0.40

b 5.33 ± 0.33

b

Alkaline phosphatase 17.60 ± 0.30b 18.03 ± 0.03

b 17.33 ± 1.45

b 15.26 ± 0.37

b 16.00 ± 1.05

b

Values are Mean ± SEM (n=5). Values in the same row carrying the same superscripts are not significantly different

(P>0.05).

Table 7. Serum Lipid Profile of rats fed the various milk samples (mmol/l)

Parameter Control Skimmed

milk


milk

Cholesterol 3.23 ± 0.03b 3.70 ± 0.05

b 1.76 ± 0.08

a 2.10 ± 0.15

b 3.13 ± 0.78

b

High density lipoprotein 0.83 ± 0.01b 0.91 ± 0.00

b 0.47 ± 0.03

b 0.58 ± 0.04

b 0.64 ± 0.17

b

Low density lipoprotein 1.96 ± 0.03b 2.33 ± 0.06

b 0.77 ± 0.08

a 1.26 ± 0.08

b 2.03 ± 0.61

b

Triglycerides 1.73 ± 0.03a 2.26 ± 0.08

a 2.43 ± 0.12

a 1.06 ± 0.08

a 1.60 ± 0.05

a

Values are Mean ± SEM (n=5). Values in the same row carrying different superscripts are significantly different

(P<0.05).



DISCUSSION

The results of proximate composition of the

milk samples as depicted in Table 1 shows a

slight variation in the energy values of whole

milk, flavoured milk and soya milk. This

variation was due to the energy contents

obtained from the carbohydrate, crude protein

and fat contents of the milk samples. The

highest energy value was obtained from whole

milk, while skimmed milk had the least energy

value. The consumption of skimmed milk is

therefore recommended for those who wish to

reduce their calorie intake.

Results of crude protein revealed that the

consumption of skimmed milk, whole milk and

soya milk are good dietary sources of protein. It

is reported that an adult would have to drink

about two liters of milk to satisfy the

recommended daily allowance for protein (60–

70g) (Pamplona-Roger, 2004).

The ash content of a food sample is a

reflection of its mineral element composition.

Skimmed milk was shown to have the highest

ash content, followed by soya milk, with the

least ash content obtained from flavoured milk.

The higher ash content in the skimmed milk

analysed revealed a rich composition of

mineral elements, especially the macro

elements.

One cup of 236 ml whole milk contains

approximately 629kJ (150kcal) and 8 grams of

fat (5 grams of which are saturated) as

compared with 356kJ (85kcal) and 0.4g fat in

one cup of skimmed milk (United States

Department of Agriculture, 1976). The highest

crude fat was obtained from whole milk when

compared with the fat contents of the other

milk samples while skimmed milk had the least

crude fat content. The least crude fat obtained

from skimmed milk is a reflection of its

reduced fat (calorie) content during the

production process. Hence, adults who wish to

reduce their calorie intake from milk products

should be encouraged to consume skimmed

milk. The moisture content of the milk samples

was highest in flavoured milk, and this tends to

decrease its keeping property. Whole milk had

the least moisture content which may indicate

that it would keep longer than other samples.

Of the milk samples analysed, only soya

milk had a fiber content which could be

attributed to the fact that it is obtained from

plant source, as opposed to processed milk

from animal source. Soya milk proved to be an

excellent source of dietary fiber, hence its

consumption should be highly recommended.

The carbohydrate content of soya milk was

low, as compared with the carbohydrate

contents in the processed milk samples.

Flavoured milk was shown to contain the

highest carbohydrate content.

Vitamin content analyses as presented in

Table 1 showed skimmed milk, whole milk,

and flavoured milk to be good sources of

vitamin A as opposed to the content in soya

milk. Thus processed dairy milk powder

provides the daily recommended intake of this

vitamin being 600–900 mg for adults, and 300–

400 mg for children (Daily Reference Intakes,

2001).

Results shows the milk samples to be a

poor source of vitamin B1 (thiamin), as they do

not provide the daily recommended need of

0.9–1.2 mg/day (for adults) and 0.5–0.6 mg/day

for children (Daily Reference Intakes, 1998).

The consumption of approximately 28 grams of

skimmed and flavoured milk by adults and

children can provide the daily intake of vitamin

B2 (riboflavin), being 0.5–0.6 mg for children

and 0.9–1.3 mg for adults (Daily Reference

Intakes, 1998). These milk samples show them

to be poor sources of vitamin B3

(Nicotinamide) as they do not provide the daily

requirement for this vitamin. Soya milk proved

to be good sources of vitamins B6 (pyridoxine)

and B12 (cobalamine), when compared to the

contents derived from the processed milk

samples. The Daily Reference Intake of vitamin

C by adults is 45–90 mg and 15–25 mg for

children. Result of proximate composition of

the whole milk powder used for this study is

shown to provide the daily need of this vitamin

by both adults and children. The milk samples

also proved to be poor sources of vitamin E



since they do not provide the required daily

intake for both children and adults. The mineral

elements constitute an important group of

nutrients required by the body for optimal

functions (WHO, 1996). They are divided into

macro minerals (sodium, potassium,

magnesium, calcium and phosphorus) and trace

elements (iron, zinc, copper and manganese).

The sodium content of the milk samples

prove to be poor sources of sodium since they

do not provide the daily reference intake of

1.0–1.2g (for children), and 1.2–1.5g for adults

(DRI, 2001). The estimated safe and adequate

daily dietary intake for potassium is 550–4575

mg in children, and 1875–5625 mg in adults

(Daily Reference Intakes, 2001). Result shows

that the milk samples analyzed do not

contribute to the daily requirement of this

element. Skimmed milk had the highest

calcium and phosphorus content with soya milk

had the least calcium and phosphorus content.

This indicates that consumption of skimmed

and whole milk can provide the daily need for

calcium and phosphorus in both children and

adults. In this present study, soya milk was

shown to contain the highest magnesium

content over the dairy milk products analyzed.

Soya milk consumption contributes to the

recommended daily allowance of magnesium in

children, being 70–170mg/day, but not for

adults who require about 270–400mg/day

(Food and Nutrition Board, 1989).

The milk samples analyzed were found to

contain 0.17–15.30mg of iron per 100 gram. Of

these, soya milk had the highest iron content

than the processed milk samples. Consumption

of soya milk as dietary source of iron should be

encouraged. The milk samples had zinc

contents of between 0.20 and 31 mg per 100

gram. The recommended daily allowance of

this element is 10 mg for children and 12–

15 mg for adults (FNB, 1989). Result of

analysis shows that the consumption of whole

milk provides a remarkable contribution of this

element in both adults and children, due to its

high zinc content. The copper content of the

milk samples was found to be below the

recommended daily intake. Although soya milk

had the highest copper intake, these milk

samples should not be consumed by adults or

children deficient of this element as sources of

dietary copper. The estimated safe and

adequate daily intake of manganese is 1–2mg

in children, and 2–5 mg in adults (FNB, 1989).

Results of proximate composition of

manganese range between 0.01 and 0.10 mg

per 100 gram. This shows that the milk samples

to be poor sources of this element.

The results of phytochemical screening of

soya milk as shown in Table 2 indicates the

presence of moderate concentration of

glycosides, steroids, reducing sugars, and high

concentration of terpenoids. Alkaloids,

flavonoids and tannins were found to be absent

in soya milk.

Results obtained from rat feeding studies

shows increase in body weights of rats in all

groups (Table 3). Rats fed soya milk showed a

considerable weight gain when compared with

rats fed dairy milk samples. The least weight

gain was observed in rats fed skimmed milk,

followed by rats fed whole milk. As a result,

adults who wish to control their weight, with a

significant reduction of their calorie intake

should be encouraged to consume skimmed

milk in preference to whole and flavoured milk.

Skimmed milk ability to cause the least weight

gain is due to its low calorie content (Table 1)

when compared with those of whole milk, soya

milk and flavoured milk.

From the results of hematological

investigations (Table 4), it was observed that

consumption of skimmed milk, whole milk and

flavoured milk by rats resulted in a significant

decrease in hemoglobin concentration and

packed cell volume. The hemoglobin and

packed cell volume concentrations are basic

values revealing the degree of anemia.

Although the hemoglobin concentration and

packed cell volume of rats fed soya milk were

slightly lower than the reference values, these

values were significantly higher than the values

obtained for rats fed the other milk samples.

Soya milk has been reported to be a rich source

of iron (Murray-Kolb, et al., 2003).

Consumption of soya milk as a source of

dietary iron is therefore encouraged.



The results of biochemical estimations are

presented in Table 5. Total protein is the sum

of albumin (60%) and globulins in the serum.

Albumin is synthesized by the liver using

dietary protein. A decrease in serum total

protein and albumin concentration was

observed in rats fed soya milk. This decrease

may be due to the soy protein not digested and

absorbed properly.

The creatinine concentration of rats in all

groups reveals normal and healthy values.

Although no significant difference (P>0.05) in

the creatinine concentration of rats in all groups

was observed, rats fed with soya milk had the

highest creatinine concentration. The effect of

the milk samples on serum creatinine did

indicate any harmful benefits on milk

consumption.

Rats fed with soya milk had the highest

urea concentration when compared to the

control group. The urea concentration of rats

fed with skimmed milk, whole milk, and

flavoured milk were slightly lower than the

value obtained from rats fed soya milk.

The bilirubin concentration of rats in each

group was with normal clinical values (Table

5). Bilirubin is formed by the breakdown of

hemoglobin in the liver, bone marrow and

spleen. An increase in plasma bilirubin results

in jaundice. Although no significant difference

was observed (P>0.05) in the bilirubin

concentration of both the test and non-test

groups, the highest direct bilirubin

concentration was observed in rats fed with

whole milk, with the control group having the

highest total bilirubin concentration. The effect

of the milk samples analysed on serum

bilirubin did not indicate the presence of

jaundice.

Enzyme assay is usually conducted to

determine the health condition of tissues

especially the liver and heart. High activities of

these enzymes in the blood are an indication of

tissue damage. No significant difference

(P>0.05) was observed in aspartate

aminotransaminase, alanine aminotransaminase

and alkaline phosphatase activities of rats in all

groups. The results indicates a slight lower

aspartate aminotransaminase activity in rats fed

skimmed and flavoured milk when compared

with the control, while rats fed soya milk and

flavoured milk had lower alanine

aminotransaminase activities as compared with

the control group. The alkaline phosphatase

activity of rats fed with skimmed milk was

higher than the control, while rats fed with

whole milk, soya milk and flavoured milk had

lower alkaline phosphatase activities when

compared with the control. The effect of the

milk samples on enzyme activities of rats in

each group revealed healthy concentrations

when with normal clinical values.

The result of lipid profile analyses is shown

in Table 7. Rats fed with skimmed milk had

the highest serum cholesterol and high density

lipoprotein cholesterol, which were within

normal clinical values. Contrary to the expected

elevated level of serum cholesterol

concentration in rats fed whole milk, a

hypocholesteremic effect was observed. Rats

fed with soya milk and flavoured milk also had

reduced cholesterol concentration when

compared with the control group. Soya milk

has been shown to decrease serum total

cholesterol level in rats (Anderson et al., 1995;

Zhan and Ho, 2005). Consumption of whole

milk, soya milk and flavoured milk did not lead

to increased concentration of high density

lipoprotein cholesterol in this study, instead, a

reduction was observed. Comparison of the

cholesterol and high density cholesterol

concentrations with normal clinical values,

revealed healthy levels in rats fed with

skimmed milk, while rats in the other groups

had lower concentrations.

Rats fed with skimmed and flavoured milk

had a higher low density lipoprotein cholesterol

concentration when compared with control,

which is between normal reference values. It is

important to note that soya milk and whole

milk consumption by rats led to a significant

lowering of serum low density lipoprotein

cholesterol.

An elevated concentration of triglycerides

was observed in rats fed skimmed and whole



milk when compared with the control, with

whole milk having the highest triglyceride

concentration. The least concentration was

observed in rats fed with soya milk, which

indicate that soya milk had beneficial effect on

triglyceride. Result shows that consumption of

skimmed milk, whole milk and flavoured milk

had positive effect on serum triglyceride level.

CONCLUSION

Although the highest weight gained was

observed in rats fed with soya milk, results of

lipid profile analysis revealed the health benefit

of consuming the non-dairy product. A

hypocholesteremic effect was observed in rats

fed whole milk, soya milk and flavoured milk.

The benefit of skimmed milk on weight gain

was also observed. Thus, the consumption of

skimmed milk by adults who wish to control

their weight should be encouraged, since

consumption of this milk led to the least weight

gain by rats. The effect of these milk samples

did not reveal potential harm on human health.

Consumption of soya milk over the processed

milk samples evaluated should be encouraged.

In conclusion, the hypothesis that consumption

of whole milk leads to coronary heart diseases

due to its saturated fat content was not

confirmed by this study.

RECOMMENDATION

This relatively short-term study indicates

that soya milk appears to have beneficial

advantages over the processed milk samples

studied. A longer term effect of these milk

samples, with further investigation on

flavoured milk should be evaluated.

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Source of Support: NIL Conflict of Interest: None Declared

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