TILAPIAS FROM DIFFERENT TILAPIAS FROM DIFFERENT AQUACULTURE SYSTEMS CONTAIN AQUACULTURE SYSTEMS CONTAIN VARIABLE AMOUNTS OF VARIABLE AMOUNTS OF -3-3 AND AND -6-6 POLYUNSATURATED FATTY ACIDS:POLYUNSATURATED FATTY ACIDS:IMPLICATIONS FOR HUMAN NUTRITIONIMPLICATIONS FOR HUMAN NUTRITION

Ioannis T. Karapanagiotidis1*, Michael V. Bell1,

David C. Little1,2, Amararatne Yakupitiyage2

1Institute of Aquaculture, University of Stirling, UK2AARM, SERD, Asian Institute of Technology (AIT),

ThailandSupport from the Aquaculture and Fish Genetics Programme, DFID,

UK

BasicBasic ConceptsConcepts

Fatty acids are the basic units of fats and oils (lipids)

The polyunsaturated fatty acids (PUFA) are a group of fatty acids with great significance in animal nutrition (including fish and humans)

PUFA are categorised according to their chemical structures, from which the most important are those of the -3 and -6 fatty acids.

The Importance of PUFAThe Importance of PUFA

-3 and -6 PUFA are essential (Essential Fatty Acids or EFA) for normal growth, development and reproduction of all vertebrate organisms, including fish & humans

Because of the fact that animals cannot synthesise -3 and -6 PUFA inside their body (de novo), these should be provided from the diet

The Vital Importance of The Vital Importance of -3 PUFA-3 PUFA

Particularly the -3 PUFA (i.e.DHA & EPA) have beneficial effects on general health and prevent many health disorders such as:

• Diseases of the heart & of blood vessels• Diseases of the immune system• Cancer & respiratory diseases• Allergic reactions

The Human Diet – The Human Diet – A growing A growing concernconcern In recent decades, it is fact that the

profiles of fats in Western diets have become increasingly unbalanced

The intake of saturated fat and -6 PUFA has increased, whereas -3 PUFA intake has decreased

Formerly the ratio -3/-6 was 1:5 but it has now declined to ratios below 1:20

Changes in Fat and Fatty Acid Intake in Western Diets(source: International Fishmeal & oil Manufacturers Association)

0

5

10

15

20

25

30

35

40

45

calories from fat (%)

0

0.4

0.8

1.2

1.6

2 ratio

Total Fat

Saturated Fat

The Human Diet – The Human Diet – A growing concernA growing concern

These changes in the fat patterns have been linked with many common health disorders in the western world (i.e. Coronary Heart Disease, cancer etc.)

However, these changes appear to be spreading and influencing diets around the World

The incidence of many health disorders is now increasing in several countries in Asia

The Availability of Fats by economic group (1961-1990, 165 countries) Source: FAO Food balance sheets, Agrostat PC, 1993

Increase between 1961 and 1990

1961 1990 %

Developing countries 28 50 78

Africa 38 43 13Far East 22 45 105

Near East 46 72 56Latin America 51 75 47

Developed countries 93 128 38

Former USSR 69 107 55Oceania 125 138 10Europe 104 143 37

North America 124 151 22

RegionFat

g/caput/day

Fish is not only a high-quality protein food, for which there are many competing alternatives in nature

But also contains high concentrations of -3 PUFA

(i.e. DHA & EPA) for which there are currently no real competing alternatives

Fish is by far the richest source of -3 in nature

Fish in the Human Diet: Fish in the Human Diet: A Unique Nutritional RoleA Unique Nutritional Role

Linkages between lipids and rural Linkages between lipids and rural aquacultureaquaculture The inland Asian communities are

traditionally dependent on freshwater aquatic foods, and especially fish

There is an increasing reliance on farmed fish as diets and livelihoods change

Is this more better? What are the qualitative impacts of increasing fish consumption through intensification of aquaculture?

Impacts of intensificationImpacts of intensification

Most aquaculture production in Asia is semi-intensive relying on use of both fertilisation and supplementary feeding

The traditional supplementary feeds are high energy brans and oilcakes, which are high in -6 PUFA

The increasing trend towards intensive systems is making use of formulated feeds to satisfy the nutrient requirements of fish

The fish feeds are using an increasing proportion of global marine fishmeal (rich in -3 PUFA), but the least cost formulations, commonly practised, result in more -6 PUFA.

The current studyThe current study

to determine the fat content and fatty acid composition of tilapia (Oreochromis niloticus) produced in systems across a range of intensification

Culture SystemsCulture Systems

Wild fish (reservoir) Nile tilapia natural food

Extensive Polyculture in snakeskin gourami

pondNile tilapia

natural food & minimum

inputs

Integrated with chicken Nile tilapianatural food &

spilled feed

Semi-Intensive culture Nile tilapiafertilised &

supplementary

Intensive pond culture Nile tilapiaonly pelleted

feed

Intensive cage culture in river

Red tilapiaonly pelleted

feed

Culture System Species Feed Inputs

Total Lipid (%) of wet weight muscle tissue

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

wild polyculture integrated semi-intensive intensive nile red Tilapia

TL

The Amounts of FA in edible muscle tissue (mg/g)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

wild polyculture integrated semi-intensive intensive red tilapia

mg/g

Saturated

MUFA

PUFA

ratios (in edible muscle tissue)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

wild polyculture integrated semi-intensive

intensive red tilapia

mg FA/g tissue

0.0

0.5

1.0

1.5 w-3/w-6

Individual Fatty Acids (% of Total FA content)

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

wild polyculture Integrated Semi-intensive

Intensive Red tilapia

EPA

DHA

18:2 n-6

Conclusions of the studyConclusions of the study

The fat content of tilapia is moderate but increases as we shift from extensive production totally dependent on natural food to more intensive culture systems.

Tilapia contain considerable amounts of the valuable DHA in the edible muscle tissue

Conclusions of the studyConclusions of the study

-3/-6 ratios in tilapia cultured at different intensities ranged from 1:1 to 1:2, indicating their high lipid nutritional value

However, higher levels of -6 and lower ratios of -3/-6 were found in the more intensively farmed fish compared to the wild fish and those cultured mainly on natural food.

General ConclusionsGeneral Conclusions

The aquaculture sector has a very important role to play both in the developing and developed world by providing food security and ensuring future fish supplies. Fish is the richest source of the -3 PUFA in nature and consumption of fish improves human nutrition and health.

However, since the input of -6 PUFA from other dietary components is often excessive in humans it is desirable, or even essential, that fish continue to supply long-chain -3 PUFA in the human diet.

RecommendationsRecommendations

Participation of the feed industry assessing the

potential for developing feed formulations that

enhance -3:-6 ratios to optimal

a better understanding of the underlying

mechanisms that result in more desirable ratios

observed in less intensively farmed and natural

stocks

RecommendationsRecommendations

An assessment of the fat quality of other

common aquatic animals, cultured and natural

stocks, consumed by rural communities

Awareness raised among change agents and

policy makers that production methods can affect

fish quality and that these in turn may have

impacts on human health

Thank youThank you