Livestock Research for Rural Development 22 (4) 2010 Notes to Authors LRRD Newsletter

Citation of this paper

Moringa oleifera leaf meal as a hypocholesterolemic agent in laying hen diets

T S Olugbemi, S K Mutayoba and F P Lekule

Department of Animal Science and Production, Sokoine University of Agriculture, P.O. Box 3004, Morogoro, Tanzania
olugbemitaiye1@yahoo.com

Abstract

Moringa oleifera has being studied in human nutrition because of its nutritional benefits. However, its hypocholesterolemic potential, as attested to by traditional medical practitioners has not been extensively studied.   Due to controversies as to the role of eggs in cardiac related diseases, research has continued to focus on ways in reducing the cholesterol content.  The potential of Moringa oleifera leaf meal (MOLM) as a hypocholesterolemic agent was therefore investigated using layers fed cassava based diets over a 90 day period.  Eighty layers were assigned to four dietary treatments containing MOLM at 0, 5, and 10% (treatments 2, 3 and 4) levels with cassava chip constituting 20% of each diet and a control diet (treatment 1) containing neither cassava nor Moringa. A completely randomized design was employed.  The effect of the dietary treatments on serum and yolk cholesterol was determined. 

 

Serum cholesterol levels in  treatments 2, 3 and 4 declined by 14.2%, 19.8% and 22.0 %, respectively, while yolk cholesterol levels declined by 6.55%, 7.45% and 12.1%, respectively.

 

Results of the study indicate that Moringa oleifera possesses hypocholesterolemic properties and its inclusion in layers diets could facilitate reductions in egg cholesterol content.

Keywords: cholesterol, eggs, feed ingredients, heart


Introduction

There is a general assumption that high dietary cholesterol levels result in high serum cholesterol and consequently a higher risk of arteriosclerosis and coronary heart disease (Grundy 1990).  There has been much controversy as to the role of eggs in blood cholesterol levels however, eggs are undisputedly the highest source of dietary cholesterol.  An egg can contain up to 208mg of cholesterol (Holden et al 1989) and even more depending on its size, hence the long lasting debate as to the risk in consuming an egg a day.  Consuming one egg a day (about 200 mg cholesterol) increases the ratio of total to HDL cholesterol concentrations by 0.040 units, thereby increasing the risk of myocardial infarction (Weggemans et al 2001).  Such reports amongst others have contributed to the “egg scare” and may have created a negative influence on consumers’ attitudes toward eggs (Chen et al 2005) However, another school of thought asserts that eggs in themselves are not a threat to normal health but for those with raised blood cholesterol levels (above 5.2 mmol/L), reducing the amount of high-cholesterol foods such as eggs will help  reduce blood cholesterol levels (Weggemans et al 2001).  

 

While the fact remains that the human body produces cholesterol in the absence or presence of dietary cholesterol and less cholesterol is produced to compensate for dietary cholesterol, blood cholesterol levels still increase when dietary cholesterol is increased (Weggemans et al 2001).  Attention has recently focused on identifying ingredients or production methods that can facilitate a reduction in egg cholesterol. Genetic selection of hens for lowered cholesterol has not been successful in lowering the egg cholesterol content and research into lowering egg cholesterol has therefore centered mostly on diet and pharmacological intervention (Jacob and Miles 2000).  Cholesterol reducing measures have been by Chromium supplementation, lowering of the energy consumption of hens (Jacob and Miles 2000), production of omega 3 rich eggs and raising chickens free range (Linden 2008).

 

Moringa oleifera belongs to the single genus monogeneric family Moringaceae and is well distributed in Africa and Asia.  Apart from being a good source of vitamins and amino acids, it has medical uses (Makkar and Becker 1999; Francis et al 2005).  Moringa oleifera, otherwise regarded as a “miracle tree”, is reputed to have many medicinal properties, although many have not been scientifically substantiated.  It has been used in the treatment of numerous disease conditions (Pal et al 1995; Makonnen et al 1997; Ghasi et al 2000 and Matthew et al 2001), including heart disease and obesity due to its hypocholesterolemic property (Ghasi et al 2000).  This study therefore aimed at evaluating the potential of Moringa oleifera leaf meal (MOLM) as a cholesterol reducing agent in cassava based feeds for layers. 

 

Materials and methods 

Preparation of leaf meal

 

Moringa oleifera leaves were harvested from an orchard on the premises of the Department of Animal Science and Production farm unit of the Sokoine University of Agriculture, Tanzania.  The cut branches were spread out on a floor and allowed to dry for a period of 3-4 days under shady and aerated conditions.  The leaves were separated from the twigs before milling in a hammer mill to produce the leaf meal.  The proximate composition of MOLM is shown in Table 1.


Table 1.  Composition of Moringa oleifera leaf meal, % of DM except for DM which is on air-dry basis

Nutrients

MOLM

DM, %

94.6

Crude protein, %

28.0

Crude fibre, %

7.10

Ether extract, %

5.90

Ash, %

12.2

Nitrogen free extract, %

46.8

ME, MJ/kg

8.60

Calcium, %

2.50

Phosphorus, %

0.30


Preparation of experimental diets

 

Four iso-nitrogenous and iso-caloric diets (Table 2) were formulated incorporating Moringa oleifera Leaf Meal (MOLM) at 0, 5, and 10% levels (treatments 2, 3 and 4) with cassava chip constituting 20% of each diet and a control diet (treatment 1) containing neither cassava nor Moringa. 


Table 2.  Composition of experimental diets

Ingredients

Treatments

1

2

3

4

Maize meal

33.5

14.0

14.0

15.5

Cassava chips

0.00

20.0

20.0

20.0

MOLM

0.00

0.00

5.00

10.0

Maize bran

23.2

20.9

20.8

19.2

Cottonseed cake

6.50

7.30

6.40

5.50

Sunflower seed cake

17.0

18.0

14.0

10.0

Fish meal

10.0

10.0

10.0

10.0

Salt

0.50

0.50

0.50

0.50

Limestone

8.00

8.00

8.00

8.00

Bone meal

1.00

1.00

1.00

1.00

Premix*

0.30

0.30

0.30

0.30

Chemical analysis, % of DM

 

 

 

DM

95.3

95.5

94.9

94.9

ME, MJ/kg

11.1

10.9

10.9

10.9

CP

16.0

16.0

16.0

16.0

CF

8.07

8.70

7.75

6.76

EE

8.42

8.09

7.75

7.26

Ash

13.5

12.7

12.7

12.3

Ca

3.73

3.86

3.98

4.11

P

0.71

0.74

0.70

0.66

*Provides the following per kg of feed: vitamin mineral premix contains: vitamin A 8,000,000IU; vitamin D3
 3,000,000IU; vitamin E 8,000IU; vitamin K 2,000mg; vitamin B1 1,000mg; vitamin B2 2,5000mg; vitamin B12
5,000mg; Niacin 10,000mg; pantothenic acid 5,000mg; folic acid 500mg; choline chloride 150,000mg; manganese
80,000; iron 20,000mg, zinc 50,000mg, copper 8,000mg, iodine 2,000mg, cobalt 225mg; selenium 100mg


Representative samples from all the feed ingredients were obtained for determination of the proximate chemical analysis according to AOAC 1990 methods.  Apart from the cassava chip, which was fed whole, all the other feed ingredients were ground in a hammer mill before being mixed.

 

Management of experimental animals

 

Eighty (80) layers were randomly allocated to one of four treatments in a completely randomized design (CRD).  Each treatment comprised of 2 replicates with 10 birds per replicate kept in pens.  Feed and water were provided ad libitum and all medications and managerial practices applied when required.  The birds were group feed twice daily (9.00 and 15.30 h).  The birds were given the experimental diets for 90 days.

 

Cholesterol determination

 

Serum cholesterol

 

Blood samples were obtained from five birds per replicate, hence ten per treatment, by inserting a new sterile needle into the wing vein of the birds and extracting 1 ml of blood which was placed inside vacutainer test tubes containing Ethylene diamine tetra acetic acid (EDTA). The samples were properly shaken to mix with the EDTA in order to prevent coagulation of the blood and within two hours of collection were taken to the laboratory for serum cholesterol analysis.  The vacutainer tubes were placed in a centrifuge and centrifuged at 3000 r.p.m. for 10 minutes in order to separate the serum.  A commercial diagnostic cholesterol reagent kit (Erba Diagnostic Mannheim GmbH) was used for cholesterol determination using the following procedure.  1000l of a working reagent (supplied in the kit) was diluted with 10l of distilled water and 10l of the aliquot was then placed in a cuvette and inserted into a spectrophotometer set at 505nm in order to take the blank absorbance reading.  1000l of the working reagent was again mixed with 10l of the calibrator and a 10l aliquot taken and put in a cuvette before placing in the spectrophotometer to obtain the absorbance of the calibrator. Lastly, 1000l of the working reagent was mixed with 10l of the serum from each sample and incubated for about 10 mins at room temperature, after which an aliquot of 10l was taken and put in a cuvette and the absorbance read. The addition of the serum sample to the reagent resulted in plain and purple colours in various degrees depending on the amount of cholesterol in the sampleThe absorbance of the test sample was then recorded.

Cholesterol was determined using the following formula:

 

 

 

Yolk cholesterol

 

Ten eggs per treatment (five per replicate) were broken and yolks carefully separated into a container from which 1ml of the yolk was taken with a pipette and placed into a beaker, after which it was diluted with 1ml buffer pH 7.4 (10 mmol sodium phosphate/l, 100 mmol NaCl/l).  10l of the test sample was taken and mixed with 1000l of the working reagent and the absorbance read after incubating for 10 minutes at room temperature.  The absorbance of the blank and calibrator were determined as for the serum cholesterol.  The yolk cholesterol was calculated using the formula used for the calculation of serum cholesterol. 

 

Statistical analysis

 

The data obtained were analysed by General Linear Model (GLM) of Statistical Analysis Systems (1995) and the following model was used:

Yij = + Ti + eij

Where :

Yij = Observation on the jth bird on the ith treatment

  = General mean effect

Ti = Effect due to the ith dietary treatment

eij =  Random error

 

Results  

The influence of the treatments on the serum and yolk cholesterol is shown in Table 3 and figure 1.


Table 3.  Effect of treatment on serum and yolk cholestero

Variable

Treatments

SEM

1

2

3

4

Serum Cholesterol, mg/dl

181a

155ab

145b

141b

25.1

Yolk Cholesterol, mg/dl

282

263

261

248

17.3

ab means within rows with  the same superscript are not significantly different (P>0.05)




Figure 1.  Cholesterol trends as influenced by MOLM


There was a progressive decline (P<0.05) in serum cholesterol among treatments (181 – 141 mg/dl). However, only Treatment 1 differed significantly (P<0.05) from the rest.   Progressive, though insignificant (P>0.05) declines were similarly observed for yolk cholesterol (282 – 248 mg/dl) as MOLM levels increased.  Serum and yolk cholesterol levels from birds on Treatment 2 (cassava based diet) were numerically lower (P>0.05) than those from treatment 1 (maize based control diet) and there were also progressive declines (P>0.05) in the measured parameters with increase in the inclusion of MOLM from 5% to 10%. Serum cholesterol levels of birds on Treatments 2, 3 and 4 were 14.2%, 19.8% and  22.0 % lower than of birds on Treatment 1, while  Treatments 3 (5% MOLM) and 4 (10% MOLM) showed reductions of 6.50% and 9.02%, respectively, compared to Treatment 2.  Yolk cholesterol levels from birds on Treatments 2, 3 and 4 declined by 6.55%, 7.45% and 12.1%,  respectively, compared to  Treatment 1 while levels on Treatments 3 and 4 were 0.96% and 5.89% lower, respectively than for Treatment 2. 

 

Discussion  

Results obtained from this study show that MOLM inclusion in layer diets was instrumental in cholesterol reduction in serum and yolk.  The fact that inclusion of MOLM resulted in a decrease in cholesterol levels, affirms its potential as a hypocholesterolemic agent.  This is in agreement with the report of Ghasi et al (2000).  The relatively low reductions in this study compared with that of Ghasi et al (2000) might be due to differences in the form and quantity of Moringa oleifera included in the diets, as well as the animal type used, as crude extracts of the leaf were used in their rat study as compared with the raw meal used in the present study.  In a related study we conducted with broilers, abdominal fat was observed to be lower in birds on MOLM diets.  Higher cholesterol contents are an indication of higher fat deposition (Tewe and Bokanga 2001) which is not desirable in layers.  Reductions at these low percentages are however still significant, as a 25% reduction of the total cholesterol in plasma can reduce the incidence of coronary events by nearly 50% (Lipid Research Clinics Program 1984a and b) especially as eggs are highest major source of dietary cholesterol.

 

The mechanism of cholesterol reduction is thought to be through the lowering of plasma concentrations of LDL by B-sitosterol, the bioactive phytoconstituent isolated from Moringa oleifera (Saluja et al 1978; Kane and Malloy 1982 and Ghasi et al 2000).  Although there were no significant effects of replacing maize by cassava chips in the present study, the use of cassava as a supplement to maize in layer diets has been shown to lower cholesterol levels, probably due to its fibre content (Charina 2006).  During digestion in the intestine, cholesterol is the main component of bile acids secreted.  The fibre coats the bile acids in the intestine and is excreted in the body, subsequently causing the body to draw cholesterol from the blood to form bile acids, and thus lowering blood cholesterol level (Charina 2006)

 

Results of this study attest to the hypocholesterolemic properties of MOLM.  The main thrust however in maximizing the potential of Moringa most likely lies in the form of the leaf.  Its inclusion in the form of powder might enhance its hypocholesterolemic properties. 

 

Acknowledgement 

The authors are grateful to the African Network of Scientific and Technological Institutions (ANSTI) for providing funds to conduct this research.

 

References 

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Received 19 January 2009; Accepted 18 March 2010; Published 1 April 2010

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