nutritional benefits of higher welfare animal products report sept

8/10/2019 Nutritional Benefits of Higher Welfare Animal Products Report Sept

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CONTENTS

EXECUTIVE SUMMARY

1. Introduction

2. Welfare potential of the production systems being compared

3. Key nutrients that may differ between higher- and lower-welfareproduction systems

3.1 Fat quantity and composition

3.2 Antioxidants

3.3 Iron

4. Analysis of nutritional differences between higher- and lower-welfareanimal products

4.1 Lamb

4.2 Beef

4.3 Milk

4.4 Pig meat

4.5 Chicken meat

4.6 Eggs

4.7 Salmon and trout

5. Summary of findings for each nutrient group

6. Conclusions

LIMITATIONS AND FURTHER RESEARCH

GLOSSARY

REFERENCES

ACKNOWLEDGEMENTS

Report compiled for Compassion in World Farming by Heather Pickett1. Comments were receivedfrom Tracey Jones2, Emily Lewis-Brown2, Phil Brooke2 and Heleen van de Weerd2.1Pickett Animal Welfare Research, 2Compassion in World Farming.

The report is downloadable fromciwf.org/nutrition


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EXECUTIVE SUMMARY

One of the main reasons cited by consumers for purchasing higher-welfare animal products is aperception that they are healthier. If this perception is true, choosing higher-welfare animalproducts over intensively-produced animal products could be expected to have a beneficial effecton consumers health, with potential implications for dietary advice and opportunities for themarketing of higher-welfare animal products on the basis of nutritional advantages.

Conventional production systems typically involvepermanent indoor housing and the use oflivestock breeds selected for high productivity. Theformer may restrict opportunities for exercise andbehavioural expression, whilst the latter isassociated with a number of production-relatedconditions that may cause serious animal healthand welfare problems. In general, extensivefarming systems are considered to have thepotential for higher animal welfare than intensivesystems. Animal products produced in extensive

systems that offer greater opportunities forexercise and behavioural expression (e.g. pasture-based, free-range and organic) and/or from lessproductive breeds (e.g. slower-growing meatchickens) may have nutritional advantages as aresult of, for example, the consumption of freshforage and greater physical activity, altering thequality of the meat, milk and eggs produced bythese animals.

A literature review was conducted in order toexamine the evidence for a range of nutritional

benefits of higher-welfare animal products. Thestudies selected compared an extensive productionsystem (free-range, organic or other pasture-basedsystem) with an intensive production system (cage,indoor or feedlot system). For chicken, studieswere also included that compared slower-growingbreeds with conventional fast-growing breeds.

For salmon and trout, data were not available tocompare organically-farmed fish with intensively-farmed fish. Studies comparing wild-caught fishwith intensively-farmed fish were thereforeselected. Despite serious welfare concernsregarding common methods of capture, handlingand processing of wild-caught fish, wild-caughtfish are considered to be the higher welfareoption in this study. Farmed salmon and trout arenot only subjected to prolonged confinement, butrequire large numbers of wild-caught fish,subjected to inhumane capture, handling andprocessing, in order to produce their feed.

Comparative data were available in the scientificliterature to allow an analysis of fat content, fatcomposition, protein content, levels of

antioxidants such as vitamin E and beta-carotene,and iron content across a range of species and

products. In general, protein content and theoverall proportions of saturated and unsaturatedfatty acids did not differ consistently betweenhigher and lower-welfare systems; data aretherefore not presented. Significant differenceswere however found in the proportions of omega-3 and omega-6 polyunsaturated fatty acids, whichare relevant to human health; data are thereforepresented. Modern western diets are oftendeficient in omega-3 fatty acids and have excessiveamounts of omega-6 fatty acids relative to omega-

3. Additionally, an adequate intake of long-chain(20 carbon atoms) omega-3 fatty acids isimportant for brain and heart health, particularlyDHA (docosahexaenoic acid) as its synthesis fromshorter chain omega-3 within the body is believedto be limited.

For most species, studies published since 2000were included. However, fewer studies wereavailable for eggs and fish, so studies publishedsince 1990 were included for these. Studies withvery small sample sizes, or not published in

English, were excluded. Studies (or data within astudy) were also excluded where animals in one orother of the systems compared weresupplemented with additional quantities of any ofthe nutrients of interest.

LambThere are no consistent differences in total fatcontent between lamb from pasture-based andintensive systems. However, pasture-reared lambhas a higher proportion of omega-3 fatty acidsand a more favourable (lower) ratio of omega-6 toomega-3 fatty acids compared with intensively-reared lamb. Choosing pasture-reared lamb overintensively-reared lamb would be expected tomake a significant contribution to meetingnutritional requirements for long-chain omega-3fatty acids. This has been demonstrated in humantrials, where an increase in long-chain omega-3fatty acids in blood plasma and platelets wasevident following consumption of pasture-rearedbeef and lamb as opposed to intensively-rearedbeef and lamb. In Australia, consumption of beefand lamb from predominantly grass-fed animals isestimated to contribute 28% of total dietary

intake of long-chain omega-3.


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No data were available to compare levels ofantioxidants or iron between intensively-rearedand pasture-reared lamb.

BeefPasture-reared beef contains between 25% and50% less fat than intensively-reared beef and has

a higher proportion of omega-3 fatty acids and amore favourable (lower) ratio of omega-6 toomega-3 fatty acids compared with intensively-reared beef. Choosing pasture-reared beef overintensively-reared beef would be expected tomake a significant contribution to meetingnutritional requirements for long-chain omega-3fatty acids, as demonstrated in human trials andconsumption data from Australia.

Pasture-reared beef contains more vitamin E thanintensively-reared beef, with up to 4% of the

adult RDA in a 100g serving. Pasture-reared beefalso contains more beta-carotene than intensively-reared beef, although the amounts are small(equivalent to less than 1% of the adult RDA forvitamin A in a 100g serving). No data wereavailable to compare levels of iron betweenintensively-reared and pasture-reared beef.

MilkThere are no consistent differences in total fatcontent between milk from pasture-based andintensive systems. However, milk from pasture-based systems has a higher proportion of omega-3

fatty acids and a more favourable (lower) ratio ofomega-6 to omega-3 fatty acids compared withmilk from intensive systems. The amounts wouldbe expected to make only a relatively minorcontribution to dietary intake of omega-3 and theomega-6 to omega-3 ratio is relatively low in allsystems.

Milk from pasture-based systems contains morevitamin E than milk from intensive systems,although the amounts are small (less than 1% ofthe adult RDA in a 100ml serving). Milk from

pasture-based systems also contains more beta-carotene than milk from intensive systems, butagain the amounts are small (equivalent to lessthan 1.5% of the adult RDA for vitamin A in a100ml serving). No data were available to comparelevels of iron between milk from intensive andpasture-based systems.

Pig meatThere are no consistent differences in total fatcontent between pig meat from free-range/organic systems and intensive systems.

However, pig meat from free-range and organicsystems has a higher proportion of omega-3 fattyacids and a more favourable (lower) ratio of

omega-6 to omega-3 fatty acids compared withpig meat from intensive systems. The amountswould be expected to make only a relatively minorcontribution to dietary intake of omega-3 and theomega-6 to omega-3 ratio is relatively high in allsystems. Data from Australia indicate porkcontributes around 4% of the long-chain omega-3

intake.

Free-range pig meat contains more vitamin E thanintensively-reared pig meat, with up to 5% of theadult RDA in a 100g serving. Free-range pig meatalso contains more iron than intensively-reared pigmeat, with up to 3.5% of the adult RDA in a 100gserving.

Chicken meatBoth rearing system and breed significantlyinfluence the fat content of chicken meat. Free-

range and organic chicken meat often containsless fat than intensively-reared chicken meat, insome cases as much as 50% less. Meat fromslower-growing chicken breeds also contains lessfat than fast-growing breeds: Generally around10-30% less for medium-growing strains andaround 20-65% less for slow-growing strains.

Free-range and organic chicken meat generallyhas a higher proportion of omega-3 fatty acidscompared with intensively-reared chicken meat,with a similar ratio of omega-6 to omega-3.Similarly, chicken meat from medium-growing

strains generally has a higher proportion ofomega-3 fatty acids compared with fast-growingstrains, with a similar ratio of omega-6 to omega-3. The meat from very slow-growing layer strains(those selected for egg production) has asignificantly higher proportion of omega-3compared with fast- and medium-growing broilerstrains (those selected for rapid growth). Thebreast meat of layer strains also has a morefavourable (lower) ratio of omega-6 to omega-3and is particularly rich in long-chain omega-3,including DHA. Choosing higher-welfare (free-

range/organic and slower-growing) chicken overintensively-reared fast-growing chicken would beexpected to make a significant contribution tomeeting nutritional requirements for long-chainomega-3 fatty acids. Data from Australia indicateconsumption of chicken contributes an estimated10% of total dietary intake of long-chain omega-3.

Based on the limited data available, utilising themales of layer breeds for meat production wouldbe expected to produce meat with significantlyhigher levels of long-chain omega-3. It is standardpractice, however, to kill these male chicks posthatching as they are generally considereduneconomic to rear for meat. Creating a premium


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market for these birds based on the nutritionalqualities of the meat would be highly desirablefrom an ethical point of view, given the hundredsof millions of male layer chicks killed posthatching in the EU every year.

Levels of vitamin E are higher in the meat of

slower-growing strains compared with fast-growing strains, although the differences arerelatively small. Chicken meat from slower-growing strains and from birds reared organicallycontains more iron than meat from fast-growingstrains and birds reared intensively, with higherwelfare options providing around 5-6% of theadult RDA in a 100g serving.

EggsThere are no consistent differences in total fatcontent between eggs from free-range/organic

systems and battery cage systems. However, free-range and organic eggs generally have a higherproportion of omega-3 fatty acids and a morefavourable (lower) ratio of omega-6 to omega-3compared with battery cage eggs. Some free-range eggs are a particularly rich source of long-chain omega-3, including DHA. Choosing free-range eggs over battery eggs would be expectedto make a significant contribution to meetingnutritional requirements for long-chain omega-3fatty acids.

Free-range eggs often contain more antioxidants(vitamin E, beta-carotene and lutein) comparedwith battery cage eggs and are a rich source ofvitamin E, providing around 25% of the adult RDAin a 100g (2 eggs) serving. No data were availableto compare levels of iron between free-range/organic and battery cage eggs.

Salmon and troutWild salmon generally contains between 40% and60% less fat than farmed salmon, with a similarproportion of omega-3 fatty acids. Wild troutgenerally contains between 25% and 80% less fatthan farmed trout and contains a higherproportion of omega-3 fatty acids. Both wild andfarmed salmon and trout contain a highproportion of omega-3 fatty acids, including DHA,and can make a substantial contribution tomeeting nutritional requirements for long-chain

omega-3 fatty acids. However, wild salmon andtrout have a lower ratio of omega-6 to omega-3fatty acids compared with farmed salmon andtrout, which may be beneficial in contributing to amore balanced ratio of these fatty acids in thediet.

Wild trout contains more iron than farmed trout,with around 5% of the adult RDA in a 100gserving. No data were available to compare levelsof antioxidants between wild and farmed fish.

Higher-welfare animal products were shown to have a number of nutritional benefits over intensively-rearedanimal products. Excessive fat consumption can contribute to weight gain and associated health problems. Higher-welfare animal products are often significantly lower in fat than equivalent products from intensively-rearedanimals. This is true of pasture-reared beef, free-range and organic chicken and chicken of slower-growing breeds,and wild salmon and trout.

Choosing higher-welfare animal products over intensively-reared animal products would be expectedto be beneficial in reducing dietary intake of fat, including saturated fat.

Modern western diets are often deficient in omega-3 fatty acids and have excessive amounts of omega-6 fattyacids relative to the amount of omega-3. An adequate intake of long-chain (20 carbon atoms) omega-3 fattyacids is particularly important for brain and heart health. Compared with intensively-farmed animal products,higher-welfare animal products typically have higher levels of omega-3 fatty acids and a more favourable (lower)

ratio of omega-6 to omega-3 fatty acids. Wild salmon and trout, pasture-reared lamb and beef, chicken meat fromslow-growing layer-type strains and some free-range eggs are particularly beneficial in this respect.

Choosing higher-welfare animal products over intensively-reared animal products would be expectedto make a substantial contribution to meeting dietary requirements for long-chain omega-3 fatty acidsand achieving a more balanced intake of omega-6 and omega-3 fatty acids.

Higher-welfare animal products often contain higher levels of antioxidants, such as vitamin E and beta-carotene,and higher levels of iron, compared with intensively-produced animal products.

Choosing higher-welfare animal products over intensively-reared animal products would be expectedto make a moderate contribution to meeting dietary requirements for vitamin E and iron.


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1. Introduction

High standards of farm animal welfare and extensive production systems are associated inconsumers minds with healthy, high quality products. When asked to choose up to three reasonswhy European consumers buy products produced in a more animal-friendly way, the top answer,given by half (51%) the respondents, was that they perceived these products to be healthier(Eurobarometer, 2007).

If this perception is true, choosing higher-welfareanimal products over intensively-produced animalproducts could be expected to have a beneficialeffect on consumers health, with potentialimplications for dietary advice and opportunitiesfor the marketing of higher-welfare animalproducts on the basis of nutritional advantages.

Conventional production systems typically involvepermanent indoor housing and the use oflivestock breeds selected for high productivity. Theformer may restrict opportunities for exercise and

behavioural expression, whilst the latter isassociated with a number of production-related

conditions that may cause serious animal healthand welfare problems. Animal products producedin systems that offer greater opportunities forexercise and behavioural expression (e.g. pasture-based, free-range and organic) and/or from lessproductive breeds (e.g. slower-growing meatchickens) may have nutritional advantages as aresult of, for example, the consumption of freshforage and greater physical activity. This reportexamines the evidence for a range of nutritionalbenefits of higher-welfare animal products, usingextensive production as an indication of farming

systems with the potential for higher animalwelfare.

2. Welfare potential of the production systems being compared

Welfare can be poor in any farming system if stockmanship is poor. However, systems vary intheir potential to provide good welfare. Even if stockmanship is good, welfare is likely to bepoor in confinement systems that severely restrict freedom of movement or in barrenovercrowded conditions that limit behavioural expression.

A farming system that provides for behaviouralfreedom without compromising health can bedescribed as having high welfare potential. Majorconcerns for animal welfare arise from farmingsystems with low welfare potential, i.e. those thatfail to meet the behavioural and physical needs ofthe animal and are therefore likely to causesuffering. The ability of a system to provide goodwelfare is determined by factors that are built intothe system. Building blocks of a good systeminclude the provision of adequate living space and

access to resources to meet the needs of theanimals.

2.1 LambFor lamb, studies were selected that compared apasture-based system (100% pasture and/ormaternal milk with dams also kept at pasture)with an intensive system (finishing indoors or in afeedlot with a ration based on concentrate andcut/conserved forage permitted but no access topasture).

Sheep who are confined and fed a diet based on

concentrate may develop abnormal behaviourssuch as wool biting (biting and eating the wool ofother sheep), considered to be redirected foraging

behaviour in sheep deprived of adequate levels ofactivity or oral stimulus (Vasseuret al, 2006):aggression can also be a problem in housed sheep.

With good stockmanship, pasture-based systemscan offer sheep a high standard of welfare,providing opportunities for exercise andexpression of a wide repertoire of naturalbehaviours, including foraging and socialbehaviour. Lambs reared at pasture often benefitfrom being kept with their dam for an extended

period.

2.2 BeefFor beef, studies were selected that compared apasture-based system (cattle kept at pasture withsome supplementation of cut/conserved foragepermitted where necessary but no feeding ofconcentrate) with an intensive system (finishingindoors or in a feedlot with a ration based onconcentrate and cut/conserved forage permittedbut no access to pasture).

Confined cattle may show increased aggression

and abnormal behaviours, such as tongue-rollingand licking of pen fixtures and other cattle,especially when kept in barren systems with


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slatted floors and high stocking densities (Broomand Fraser, 2007). Such housing conditions are alsoassociated with an increased incidence oflameness, bruising and other injuries (Ibid.).

As with sheep, pasture-based systems can offercattle freedom of movement and behaviouralexpression and the cow-calf relationship is often

maintained over an extended period.

2.3 MilkFor milk, studies were selected that compared anorganic or other pasture-based system (cows keptat pasture during the grazing season;supplementation with cut/conserved forage andsome concentrate is permitted and cows may behoused over winter) with an intensive system(cows kept largely or entirely indoors and fed atotal mixed ration or concentrate and cut/conserved forage and may also involve some

grazing; or conventional retail or bulk milk, whichmay include milk from a range of systems).

Systems where dairy cows are housed for most orall of the year are associated with a higher risk ofhealth problems and physical injuries. Forexample, studies in the UK indicate the risk oflameness is doubled when cows are keptpermanently indoors compared with cows ingrazing herds (Barkeret al, 2010, Haskellet al,2006).

Pasture-based systems offer cows freedom of

movement and opportunities for naturalbehaviour and there are a large number of studiesshowing that cows kept on pasture are healthier(EFSA, 2009).

2.4 Pig meatFor pig meat, studies were selected that compareda free-range or organic system with an intensiveindoor system.

Intensively-reared pigs are housed in indoor pens,often with high stocking densities and barrenslatted floors. In the absence of appropriate

substrate to explore, pigs redirect theirexploratory behaviour towards pen structures andother pigs, which can lead to damagingbehaviours like ear and tail biting. These abnormalbehaviours, which cause pain and injury, are a signthat the behavioural needs of pigs are not met(EFSA, 2007). As a result, many intensively-rearedpigs have their tails docked and teeth clippedwithout anaesthetic, despite an EU ban on theroutine use of these mutilations. Some higher-welfare indoor systems address this problem byproviding enrichment such as straw and higher

space allowances.

In free-range and organic systems, pigs have accessto the outdoors where they have opportunities forexercise, foraging, rooting and exploration. Straw-bedded huts or arcs are provided for shelter.

2.5 Chicken meatFor chicken, studies were selected that compared afree-range or organic system with an indoorsystem (including intensive, extensive andexperimental indoor systems) and/or slower-growing genotypes with conventional fast-growing genotypes. For the purposes of this study,the growth rates of the various chicken genotypeswere classified as follows:

Fast-growing broiler-type: Typically reachslaughter weight (2kg) in 40 days (e.g.Ross 208, Ross 308, Cobb 700, Hybro-G);

Medium-growing broiler-type: Typicallyreach slaughter weight (2kg) in 49-84

days (e.g. Naked-Neck Kabir, ISAJA57/SA77N.fr Rouge, RedBro Cou Nu/M,Prelux-Bro);

Slow-growing dual-purpose or layer-type:Typically reach slaughter weight (~2kg) in>100 days (e.g. Dual-purpose: RobustaMaculata, Gushi (Chinese Local Chicken);Layer-type: Brown Classic Lohmann, ISABrown).

Most broiler (meat) chickens are reared at highstocking densities in large closed sheds. The

overcrowded conditions can restrict the birdsability to move around freely and express naturalbehaviour.

Broiler chickens are bred for fast growth, efficientfeed conversion and large breast meat yield.Standard commercial broilers now reach aslaughter weight of 2 to 2.5kg in 35-40 dayscompared with 12 weeks 30 years ago. They growat average rates of 55 to 63g/d and can reach ratesof 100g/d near slaughter age. This rapid growthand large breast conformation has resulted in

serious health problems and limits the behaviouraland physical activity levels of the birds. At least aquarter of commercially-reared fast-growingbroilers are likely to experience pain as a result oflameness (Knowleset al, 2008; Danburyet al,2000). Fast-growing broilers also suffer from anumber of cardiovascular disorders, which cancause sudden death and are responsible for amajor portion of flock mortality (Julian, 2005).

Chickens in free-range and organic systems arereared at lower stocking densities and have accessto the outdoors. They are reared to higherslaughter ages and are usually moderately slower-growing breeds. Extensive indoor systems use


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significantly lower stocking densities thanconventional systems, usually provide enrichmentto encourage greater physical activity, and oftenuse moderately slower-growing breeds.

2.6 EggsFor eggs, studies were selected that compared afree-range or organic system with a battery cagesystem.

In conventional battery cages, each hen has just550cm2 of floor space, an area less than an A4sheet of typing paper. They are unable to stretch,flap their wings or turn around without difficulty,and are prevented from carrying out most species-specific patterns of behaviour, including foraging,perching, dustbathing and laying their eggs in anest. Conventional battery cages are prohibitedacross the EU from 2012. However, enrichedcages continue to be permitted. These cagescontain a nest, perch and a small amount of littermaterial but still provide insufficient space andheight and fail to meet many of the behaviouralneeds of hens (Compassion in World Farming,2007).

Hens in free-range and organic systems are kept inloose housing with elevated perches and littermaterial and have outdoor access, allowing themfreedom of movement and the ability to express awide repertoire of natural behaviours.

2.7 Salmon and troutFor salmon and trout, data were not available tocompare organically-farmed fish with intensively-farmed fish. Studies were therefore selected thatcompared wild-caught fish with intensively-farmed fish.

Intensive fish farming practices often cause stress

and poor welfare. Farmed fish are usually stockedat very high densities, which can have adetrimental impact on their health and welfare,especially for species that do not naturally live inclose-schooling shoals. High densities can lead toincreased incidence of physical injuries, stress, andsusceptibility to disease; poor water quality andincreased aggression (Hstein, 2004). Thebehaviour of farmed fish is severely restricted.Species like salmon would naturally swim greatdistances at sea. Confined in cages, farmed fish areunable to escape from dangers such as poor waterquality or attack by predators (including otherfish). Mortality rates of farmed fish are often veryhigh compared with other farmed animals (Poppeet al, 2002).

There are also serious welfare concerns regardingcommon methods of capture, handling andprocessing of wild-caught fish. However, inaddition to farmed fish being subjected toprolonged confinement, large numbers of wild-caught fish are subjected to inhumane capture,handling and processing in order to produce feedfor farmed salmon and trout, whereas wild salmon

and trout consume wild animals directly.Therefore, wild-caught fish are considered to bethe higher-welfare option for the purposes of thisstudy.

3. Key nutrients that may differ between higher- and lower-welfareproduction systems

The nutritional quality of animal products is influenced by many factors, including the species,breed, age and sex of the animal, the system in which the animal was reared, the composition of

the animals diet, the geographical location, climate and season.

In addition, there may be significant differences inmeasurements of nutrient composition betweendifferent laboratories and with differentmethodology of the analyses.

Comparative data were available in the scientificliterature to allow an analysis of fat content, fatcomposition, protein content, levels ofantioxidants such as vitamin E and beta-carotene,and iron content across a range of species andproducts. In general, protein content and the

overall proportions of saturated and unsaturated

fatty acidsi did not differ consistently betweenhigher and lower-welfare systems, so data forthese aspects are not presented. Significantdifferences were found in the proportions ofomega-3 and omega-6 polyunsaturated fattyacids, which are relevant to human health, so thedata presented for fat composition focus on theseaspects. The roles of these nutrients in our diet,and the reasons why levels may differ betweenanimal products from intensive and extensivesystems, are discussed below.


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i. The proportion of polyunsaturated fatty acids (PUFA) was often found to be higher in extensively-reared animal products andthe proportion of monounsaturated fatty acids (MUFA) was often higher in intensively-reared animal products but the overallproportion of unsaturated fatty acids (PUFA and MUFA combined) generally did not differ consistently. A certain amount ofspecific polyunsaturated fatty acids is essential in the diet but there is no RDA set for total PUFA or total MUFA in the EU.Replacement of saturated fat in the diet with a mixture of PUFA and MUFA is considered beneficial (EFSA, 2010) but there areno clear nutritional or health benefits of consuming higher amounts of total PUFA over total MUFA or vice versa. It wastherefore decided not to present data on the differences in levels of total PUFA and total MUFA between intensive andextensive animal products due to the limited relevance of the findings for human health and nutrition.

3.1 Fat quantity and composition

Fat is an important source of energy in the dietand facilitates the absorption of fat-solublevitamins and carotenoids. However, fat is veryenergy dense (containing 9Kcal/g compared with4Kcal/g for protein and carbohydrate) andexcessive fat consumption can contribute toweight gain and associated health problems. High-fat diets may decrease insulin sensitivity and arepositively associated with certain risk factors forcardiovascular disease (EFSA, 2010). Nutritionalguidelines generally recommend total fat shouldbe limited to no more than 30-35% of energyintake, with less than 10% of energy intake (or as

little as possible within the context of anutritionally adequate diet) coming fromsaturated fat (Ibid.).

The greater opportunity for exercise in extensivesystems (and in more active breeds) may beexpected to result in a reduction in the fat contentof meat. Based on the studies reviewed in thisreport, saturated fatty acids generally make uparound 20-25% of total fatty acids in salmon andtrout, 30-40% in chicken and eggs, 30-50% inmeat and 60-75% in milk. Given that the fat in

animal products generally contains a significantproportion of saturated fat (irrespective of theproduction system) consumption of animalproducts with reduced fat content would beexpected to facilitate a reduction in consumptionof saturated fat as well as total fat.

In addition to the total amount of fat, thecomposition of the fat is important. Keydifferences in diet between intensive andextensive systems, in particular the consumptionof fresh forage, influence the composition of fatin animal tissues, especially the levels of omega-3fatty acids.

Essential polyunsaturated fatty acids can bedivided into two groups: omega-3 and omega-6.These two groups have different and oftenopposing roles in the body. For example, omega-3fatty acids have anti-inflammatory properties andomega-6 fatty acids have pro-inflammatoryproperties (Simopoulos, 2006).

The two groups compete for positions in cellmembranes within the body and hence the

composition of these membranes is dependent toa great extent on dietary intake (Ibid.). A numberof experts have therefore highlighted the

importance of achieving an appropriate balance inthe amounts of each group consumed(Simopoulos, 2008; Hibbelnet al, 2006;Simopoulos, 2006; Cordainet al, 2005; Muskietetal, 2004).

Modern western diets are often deficient inomega-3 fatty acids and have excessive amountsof omega-6 fatty acids relative to the amount ofomega-3 (Simopolous, 2008, Hibbelnet al, 2006;Simopoulos, 2006; Cordainet al, 2005).

Anthropological and epidemiological studies

indicate human beings evolved on a diet with aratio of omega-6 to omega-3 of around 1:1,whereas in current Western diets the ratio is 15:1to 16.7:1 (Simopoulos, 2008).

A review of the scientific evidence by Simopoulos(2008) suggests that insufficient omega-3, and animbalance of the ratio of omega-6 to omega-3,promotes a number of serious diseases, includingcardiovascular disease, cancer, osteoporosis, andinflammatory and autoimmune diseases. A ratio ofomega-6 to omega-3 of 4:1 was associated with a

70% decrease in total mortality in patients withcardiovascular disease; a ratio of 2.5:1 reducedrectal cell proliferation in patients with colorectalcancer, whereas a ratio of 4:1 with the sameamount of omega-3 had no effect; a loweromega-6 to omega-3 ratio in women with breastcancer was associated with decreased risk; a ratioof 2-3:1 suppressed inflammation in patients withrheumatoid arthritis, and a ratio of 5:1 had abeneficial effect on patients with asthma, whereasa ratio of 10:1 had adverse consequences.

The omega-3 fatty acids can be further sub-

divided into long-chain omega-3 (those containing20 or more carbon atoms) and shorter chainomega-3. The major long-chain omega-3 fattyacids are EPA (eicosapentaenoic acid), DPA(docosapentaenoic acid) and DHA(docosahexaenoic acid) and the major shorter-chain omega-3 is ALA (alpha-linolenic acid). ALAcan be converted into the longer-chain versions inthe body but the process is relatively inefficient,especially for DHA (Muskietet al, 2004). It istherefore important to obtain sufficient long-chain omega-3 directly from the diet and a

number of bodies have set recommended levels ataround 200 to 500mg per day for EPA and DHAcombined (EFSA, 2010; Harriset al, 2009).


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Since conversion of shorter chain omega-3 to DHAwithin the body is believed to be limited, anadditional 100 to 200mg per day of pre-formedDHA is recommended for pregnant and lactatingwomen in order to provide sufficient DHA for thedeveloping brain of the foetus (EFSA, 2010).Hibbelnet al(2006) attempted to establishhealthy intakes of omega-3 and omega-6 fatty

acids based on the burden of cardiovasculardisease and mental illness that can be attributedto insufficient dietary intake of long-chain omega-3. They investigated dietary intakes of long-chainomega-3, the long-chain fatty acid composition ofbody tissuesii and the prevalence of morbidity andmortality from various cardiovascular and mentalillnesses in 38 countries around the world. Theyconcluded the burden of disease potentiallyattributable to deficiencyiii in long-chain omega-3is over 40% for coronary heart disease mortality,over 30% for stroke mortality, over 25% for

cardiovascular disease mortality and between 65%and 99.9% for various forms of depression,although the authors suggest the figures forcertain types of depression are likely to beoverestimates. They recommend an intake of long-chain omega-3 equivalent to that seen in Japanwould be expected to protect more than 98% ofthe population from increased risk of these

conditions. This equates to 0.37% of energy fromlong-chain omega-3 or 750mg/day for EPA, DPAand DHA combined, resulting in a tissuecomposition of approximately 60% omega-3 intotal long-chain fatty acids. However, due tovarying levels of omega-6 intake, the intake oflong-chain omega-3 required to achieve acomparable tissue composition ranged from lessthan 300mg/day in the Philippines to over3500mg/day in the US.

3.2 AntioxidantsAntioxidants are naturally occurring compoundsthat can neutralise free radicals (highly reactivemolecules that damage body cells). Antioxidantsare thought to prevent some of the processesinvolved in the development of cancer (protectingDNA from oxidative damage) and cardiovasculardisease (inhibiting oxidative damage to LDL (lowdensity lipoprotein or bad) cholesterol)(Schnfeldt and Holden, 2009).

Vitamin E acts as an antioxidant in cell membranesand plasma lipoproteins (complex aggregates oflipid (fat) molecules and protein molecules) and isespecially important in limiting damage from free-radicals generated during the oxidation ofpolyunsaturated fatty acids. There isepidemiological evidence that high intakes ofvitamin E are associated with lower incidence ofcardiovascular disease (Bender, 2009). Alpha-tocopherol is the most biologically active form ofvitamin E. The adult recommended dailyallowance (RDA) for vitamin E in the EU is 12mg

(Council Directive 90/496/EEC).

Carotenoids, such as beta-carotene and lutein, also

act as antioxidants. There is epidemiologicalevidence that diets rich in carotenoids areassociated with a lower incidence of cancer andcardiovascular disease, although interventionstudies using beta-carotene supplements have notdemonstrated this (Bender, 2009) and it istherefore recommended that beta-carotene beobtained from food rather than from supplements(Taylor Mayne, 1996). In addition to their role asantioxidants, certain carotenoids can be convertedinto vitamin A in the body (provitamin Acarotenoids).

There is no specific RDA set for any of thecarotenoids in terms of their antioxidant function.The adult RDA for vitamin A in the EU is 800g(Council Directive 90/496/EEC). 12g of beta-carotene is equivalent to 1g of retinol (pre-formed vitamin A) (Bender, 2009). In terms of itsrole as a precursor of vitamin A therefore, 9600gof beta-carotene would be equivalent to the RDAfor vitamin A. Lutein is a non-provitamin Acarotenoid and therefore there is no RDA forlutein.

Fresh forage generally contains higher levels ofantioxidants than conserved forage andconcentrate feeds, which may be expected totranslate into higher levels of antioxidants in themeat, milk and eggs produced from animalsgrazing pasture compared with those confinedindoors.

ii. Estimated based on dietary intakes of LA, ALA, AA and EPA+DPA+DHA.iii.Defined as an increased risk of chronic diseases for which substantial efficacy data exist and for which these nutrients reduce

pathophysiologic mechanisms.


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3.3 IronIron facilitates many metabolic functions,including the transport of oxygen in the blood (viahaemoglobin) and the storage of oxygen inmuscles (via myoglobin). Iron is also a componentof various enzymes that are critical for theproduction of energy from food and for immunesystem functioning (Strain and Cashman, 2009).

Iron deficiency causes anaemia, which is associatedwith fatigue, restlessness and impaired workperformance and can adversely affectpsychomotor and mental development of children(Ibid.). The adult RDA for iron in the EU is 14mg(Council Directive 90/496/EEC).

The greater physical activity of animals reared inextensive systems would be expected to lead to anincrease in myoglobin in the muscles, andtherefore to an increase in the iron content of themuscles which are eaten as meat. The breed ofanimal may also be expected to affect iron levels.Breeds of animal that have been selected for

increased growth rate and altered bodyconformation, such as fast-growing meat chickens,are relatively inactive, which would be expected toreduce the myoglobin (and hence the iron)content of the meat.

4. Analysis of nutritional differences between higher- andlower-welfare animal products

A literature review was conducted to identify studies comparing the nutritional composition ofanimal products from intensive and extensive systems. For most species, studies were includedthat were published since 2000. However, fewer studies were available for eggs and fish sostudies published since 1990 were included for these.

Studies with very small sample sizes and studiesnot published in English were excluded. Studies(or data within a study) were also excluded whereanimals in one or other of the systems to becompared were supplemented with additionalquantities of any of the nutrients of interest,

either through direct supplementation with thenutrient (above levels normally added toconventional feedstuffs) or through the use offeedstuffs specifically selected for their high levelsof the nutrient (e.g. fishmeal or linseed foromega-3 fatty acids). Some studies also examinedother aspects of food quality or safety but theseaspects are beyond the remit of this analysis andare not examined here.

In some cases, mean values were used frommultiple sets of data presented in a study. Thismay apply, for example, where studies presentdata for several muscle types or from severalproduction systems that are equivalent from ananimal-welfare perspective (e.g. multiple grazingsystems with different species composition of thepasture). For chicken, data for different muscletypes were not pooled because of the majordifferences in composition between breast meatand leg/thigh meat. Where a range of slaughterages and/or weights were compared in a study,the data used here were those considered mostrepresentative of commercial practice.

4.1 LambThe total amount of intramuscular fat (i.e. fatcontent of lean meat trimmed of visible fat) is

generally similar in lamb from intensive andpasture-based systems, with most studies thatmeasured this reporting no significant difference(Paneaet al, 2011; Valvoet al, 2005; Santos Silvaet al, 2002).

However, the composition of the fat is markedlydifferent between intensive and pasture-rearedlamb. The proportion of omega-3 fatty acids isbetween one third and five times higher inpasture-reared lamb (Fig. 1). The ratio of omega-6to omega-3 fatty acids is between 20% and 84%lower in pasture-reared lamb compared withintensively-reared lamb (Paneaet al, 2011; Kitessaet al, 2010; Arabaet al, 2009; Nuernberget al,2008; Caparraet al, 2007; Diazet al, 2005;Nuernberget al, 2005; Valvoet al, 2005; Santos-Silvaet al, 2002; Sanudo et al, 2000). All thepasture-reared lamb has a healthy low omega-6/omega-3 ratio of between 0.6 and 3.1. The ratiois more variable for intensively-reared lamb,ranging from 1.3 to 8.4.

A number of studies report the amount of omega-3 per 100g of lean meat, ranging from 31 to 78mgin intensively-reared lamb and from 65 to 130mgin pasture-reared lamb (Kitessaet al, 2010;Nuernberget al, 2008; Diazet al, 2005; Nuernberget al, 2005; Sanudoet al, 2000). In some cases,levels may be much higher, with omega-3representing over a quarter (Caparraet al, 2007)

or as much as one third (Valvo et al, 2005) of totalfatty acids in pasture-reared lamb (Fig. 1). Thelatter is equivalent to around 400mg of omega-3


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per 100g of lean meat (including 240mg long-chain omega-3, of which 68mg is DHA). iv. Typicallyaround half or more of the omega-3 in lamb ismade up of long-chain (20 carbons) omega-3(Fig. 1).

These amounts are significant in terms of humannutritional requirements (see Section 3.1) and

indicate pasture-reared lamb can make a

significant contribution to meeting nutritionalrequirements for long-chain omega-3. This issupported by data from Australia, whereconsumption of beef and lamb frompredominantly grass-fed animals is estimated tocontribute 28% of total dietary intake of long-chain omega-3 (Howeet al, 2006).

Figure 1. Omega-3 content and percentage difference between lamb from intensive and pasture-based systems.The lower (darker shaded) section of each bar represents long-chain (20 carbons) omega-3. The upper (lighter shaded) section of each bar represents 18-carbon omega-3. Bars represent the totalomega-3 fatty acids measured in each study, which may not necessarily include all omega-3 fatty acidspresent in the samples. Studies are included if they present data for at least one of the major long-chainomega-3 fatty acids (EPA, DPA and/or DHA) and the major shorter-chain omega-3 fatty acid (ALA).

A short-term (4-week) study by McAfeeet al(2011) found a measurable effect of consumptionof grass-fed beef and lamb on levels of omega-3 in

human blood. Volunteers consumed around 470gper week of either grass-fed beef and lamb orbeef and lamb from animals finished intensivelyon a concentrate-based diet. After four weeks,mean levels of long-chain omega-3 in bloodplasma and platelets were increased in thosepeople consuming the grass-fed products anddecreased in those people consuming theconcentrate-fed products. At the end of the trial,the proportion of long-chain omega-3 was 62%higher in the plasma and 23% higher in the

platelets of those people who consumed grass-fedproducts compared with those who consumedconcentrate-fed products. Both these differences

were highly statistically significant (P


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SUMMARY OF FINDINGS FOR LAMB

There are no consistent differences in total intramuscular fat content between lamb from pasture-based and intensive systems;

Pasture-reared lamb has a higher proportion of omega-3 fatty acids and a more favourable (lower)ratio of omega-6 to omega-3 fatty acids compared with intensively-reared lamb;

Pasture-reared lamb can make a significant contribution to meeting nutritional requirements forlong-chain omega-3 fatty acids and in some cases contains appreciable amounts of DHA;

An increase in long-chain omega-3 fatty acids in blood plasma and platelets has been demonstratedin human trials following consumption of pasture-reared beef and lamb as opposed to intensively-reared beef and lamb.

4.2 BeefThe total amount of intramuscular fat is between25% and 47% lower in pasture-reared beefcompared with intensively-reared beef (Fig. 2).

Under EU legislation (Regulation (EC) No.1924/2006) food products can be labelled as lowin fat if they contain less than 3g of fat per 100g.In all of the studies, pasture-reared beef trimmedof visible fat would qualify as a low-fat product,compared with only two out of eight studies forintensively-reared beef.

There are significant differences in fatcomposition between intensively-reared andpasture-reared beef. The proportion of omega-3fatty acids is generally between two and five timeshigher in pasture-reared beef (except for onestudy where the difference was not statisticallysignificant) (Fig. 3).

Also, the ratio of omega-6 to omega-3 fatty acidsis between 35% and 85% lower in pasture-rearedbeef compared with intensively-reared beef

(Alfaiaet al, 2009; Garciaet al, 2008; Latimorietal, 2008; Leheskaet al, 2008; Ponnampalamet al,2006; Descalzoet al, 2005; Realiniet al, 2004;Varelaet al, 2004). All the pasture-reared beef hasa healthy low omega-6 to omega-3 ratio ofbetween 1.4 and 3.7. The ratio is more variable forintensively-reared beef, ranging from 2.8 to 14.2.

Two studies report the amount of omega-3 per100g of lean meat: Garcia et al(2008) found levelsof 32mg in intensively-reared beef and 84mg inpasture-reared beef; Ponnampalam et al(2006)found levels of 76mg in intensively-reared beef

and 129mg in pasture-reared beef. These levelsare generally comparable with the levels found inlamb (see Section 4.1).

Figure 2. Intramuscular fat content and percentage difference between beef from intensive andpasture-based systems.


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Table 1: Comparison of intramuscular fat and omega-3 levels in beef from intensive and pasture-based systems. Within studies, statistically significant differences are indicated by different superscriptletters (lower case = P


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Figure 4. Vitamin E content and percentage difference between beef from intensive and pasture-based systems.

Figure 5. Beta-carotene content and percentage difference between beef from intensive andpasture-based systems.


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4.3 MilkMilk fat content ranges from 3.2% to 4.6% in thestudies reviewed. There are no consistentdifferences in the total amount of fat betweenmilk from intensive and pasture-based systems.

Some studies report higher levels of fat in milkfrom intensive systems (Couvreuret al, 2006;Schroederet al, 2005; Whiteet al, 2001) whilstother studies report higher levels in milk fromorganic and other pasture-based systems (Butleretal, 2011; Slotset al, 2009; Kayet al, 2005; Leiber etal, 2005). In either case, the total amount of fatmay be less relevant from a nutritional perspectivefor milk as consumers often choose milk or milkproducts with part (semi-skimmed) or most(skimmed) of the fat removed. Milk fat isconsidered useful however in the processing ofmilk into products such as cheese, butter andcream. The composition of the fat may thereforebe more important than the actual amount, sincethese products generally have a high fat contentregardless of the original fat content of the milk.

There are significant differences in fatcomposition between milk from intensive andpasture-based systems. The proportion of omega-3fatty acids is between 50% and 184% higher inmilk from pasture-based systems (Fig. 6). Also, theratio of omega-6 to omega-3 fatty acids isbetween 30% and 79% lower in milk from

pasture-based systems compared with milk from

intensive systems (Butleret al, 2011; Biliket al,2010; Slotset al, 2009; Elliset al, 2006; Leiberet al,2005). All the milk from pasture-based systems hasa healthy low omega-6 to omega-3 ratio of

between 1.0 and 3.5. Although generally higher,the omega-6 to omega-3 ratio for milk fromintensive systems is also relatively low, at between2.5 and 5.1.

Based on typical omega-3 proportions in milk fatof 0.5% in milk from intensive systems and 1% inmilk from pasture-based systems, and a typicalmilk fat content of 4%, amounts of omega-3would be expected to be in the region of 19mgand 38mg per 100ml of milk from intensive andpasture-based systems, respectively.v. Most of thisis made up of ALA, with typically 20% or less

being long-chain omega-3 (Fig. 6). These amountsare relatively small in terms of human nutritionalrequirements (see Section 2.1). However, althoughmilk may not be an especially rich source ofomega-3 by itself, within the context of a dietwhere most or all animal products are sourcedfrom extensive systems, consumption of milk frompasture-based systems rather than intensivesystems would be expected to further contributeto meeting requirements for omega-3 intake andachieving a healthy balance of omega-6 toomega-3.

v. Based on a conversion factor of 0.945 to give total fatty acids in milk fat (from MAFF, 1998).


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Figure 6. Omega-3 content and percentage difference between milk from intensive and pasture-based systems.The lower (darker shaded) section of each bar represents long-chain (20 carbons) omega-3. The upper (lighter shaded) section of each bar represents 18-carbon omega-3. Bars represent the totalomega-3 fatty acids measured in each study, which may not necessarily include all omega-3 fatty acidspresent in the samples. Studies are included if they present data for at least one of the major long-chainomega-3 fatty acids (EPA, DPA and/or DHA) and the major shorter-chain omega-3 fatty acid (ALA). * Datafrom La Terraet al(2010) are % of lipids rather than % of fatty acids.

Figure 7. Vitamin E content and percentage difference between milk from intensive and pasture-

based systems.n.s. = difference not statistically significant.


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Figure 8. Beta-carotene content and percentage difference between milk from intensive andpasture-based systems.n.s. = difference not statistically significant.

Milk from pasture-based systems contains higherlevels of antioxidants. Levels of vitamin E aregenerally between 24% and 58% higher in milkfrom pasture-based systems compared withintensive systems (except for one comparisonwhere the difference was not significant) (Fig. 7).However, the levels are relatively low in terms of

human nutritional requirements. Based on atypical milk fat content of 4%, a 100ml serving ofmilk from a pasture-based system providesbetween 0.06mg and 0.13mg of vitamin E, whichis equivalent to between 0.5% and 1% of the RDA(see Section 3.2). A 100ml serving of milk from anintensive system provides between 0.05mg and0.08mg of vitamin E, which is equivalent tobetween 0.4% and 0.7% of the RDA.

Levels of beta-carotene are generally between

60% and 436% higher for milk from pasture-based systems (except for one comparison wherethe difference was not significant) (Fig. 8).However, the levels are relatively low in terms ofhuman nutritional requirements. Based on atypical milk fat content of 4%, a 100ml serving ofmilk from a pasture-based system provides

between 64g and 128g of beta-carotene, whichis equivalent to between 0.7% and 1.3% of theRDA for vitamin A (see Section 3.2). A 100mlserving of milk from an intensive system providesbetween 52g and 81g of beta-carotene, whichis equivalent to between 0.5% and 0.8% of theRDA for vitamin A.

No data were available to compare levels of ironbetween milk from intensive and pasture-basedsystems.

SUMMARY OF FINDINGS FOR MILK

There are no consistent differences in total fat content between milk from pasture-based systems andintensive systems;

Milk from pasture-based systems has a higher proportion of omega-3 fatty acids and a morefavourable (lower) ratio of omega-6 to omega-3 fatty acids compared with milk from intensivesystems, although the amounts would be expected to make only a relatively minor contribution todietary intake of omega-3 and the omega-6 to omega-3 ratio is relatively low in all systems;

Milk from pasture-based systems contains more vitamin E than milk from intensive systems, althoughthe amounts are relatively small (less than 1% of the adult RDA in a 100ml serving);

Milk from pasture-based systems contains more beta-carotene than milk from intensive systems,

although the amounts are relatively small (equivalent to less than 1.5% of the adult RDA for vitaminA in a 100ml serving).


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4.4 Pig meatThe total amount of intramuscular fat is highlyvariable, ranging from 1.2g to 9.0g per 100g oflean meat, and there are no consistent differencesin total fat content between pig meat fromintensive and extensive systems. Some studiesreport higher levels of fat in intensively-reared pigmeat (Trombettaet al, 2009; Hansenet al, 2006)whilst other studies report higher levels in free-range pig meat (Butko et al, 2007; Carrapisoet al,2007; Ventanaset al, 2007) and others report nosignificant difference (Kimet al, 2009; Gonzalez &Tejeda, 2007; Beeet al, 2004; Hoffmanet al, 2003;Nilzenet al, 2001). Two of the three studiesshowing a higher fat content in free-range pigmeat are traditional Spanish outdoor systems forthe production of Iberian ham (Carrapisoet al,2007; Ventanaset al, 2007), where the higher fat

content of the meat can be explained by the largequantities of acorns in the diet of the free-rangepigs. These are naturally high in monounsaturatedfat and contribute to achieving the desiredsensory characteristics of the finest commercialgrade of Iberian ham.

There are significant differences in thecomposition of the fat between indoor andextensive systems. The proportion of omega-3fatty acids is higher in free-range pig meat,although the difference is not statisticallysignificant in three studies. Where significantdifferences are found, the proportion of omega-3is between 18% and 43% higher for free-rangepig meat and 291% higher for organic pig meatthan that from intensive systems (Fig. 9).

Figure 9. Omega-3 content and percentage difference between pig meat from intensive and free-range/organic systems.The lower (darker shaded) section of each bar represents long-chain (20 carbons)omega-3. The upper (lighter shaded) section of each bar represents 18-carbon omega-3. n.s. = difference notstatistically significant. Bars represent the total omega-3 fatty acids measured in each study, which may notnecessarily include all omega-3 fatty acids present in the samples. Studies are included if they present datafor at least one of the major long-chain omega-3 fatty acids (EPA, DPA and/or DHA) and the major shorter-chain omega-3 fatty acid (ALA).

The majority of studies report a lower ratio ofomega-6 to omega-3 fatty acids for free-range pigmeat, ranging from a 7% to 42% reductioncompared with intensively-reared pig meat (Sotoet al, 2009; Ventanaset al, 2007; Beeet al, 2004).Two studies report no significant difference(Oksbjerg et al, 2005; Nilzenet al, 2001). Kim et al

(2009) report a 53% lower omega-6 to omega-3ratio for organic pig meat compared withintensively-reared pig meat. However, the omega-6 to omega-3 ratio is relatively high for pig meatfrom all systems, ranging from 11.8 to 18.1 forextensive systems and from 12.4 to 31.2 forintensive systems.


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Based on typical omega-3 proportions of 1% offatty acids in intramuscular fat in intensively-reared pig meat and 1.4% in pig meat fromextensive systems, and a typical fat content of 4%,omega-3 levels would be expected to be in theregion of 36mg and 51mg per 100g of lean pigmeat from intensive and extensive systems,respectively.vi. The proportion of omega-3 in pig

meat that is made up of long-chain omega-3varies widely but is commonly between 30% and60% (Fig. 9). The generally lower amounts ofomega-3 and higher omega-6 to omega-3 ratiomean that the potential contribution of pig meatto meeting human nutritional requirements forlong-chain omega-3 is likely to be relatively minorcompared with lamb and beef. This is supportedby data from Australia indicating that porkcontributes around 4% of long-chain omega-3

intake (Howeet al, 2006). Nonetheless, thecomposition of free-range and organic pig meatcan be considered more favourable than that ofintensively-produced pig meat in this respect.

Levels of vitamin E are generally between 23%and 204% higher in pig meat from extensivesystems compared with intensive systems (except

for two comparisons that show no significantdifference) (Fig. 10). A 100g serving of free-rangeor organic pig meat provides between 0.2mg and0.6mg of vitamin E, which is equivalent tobetween 1.7% and 5% of the RDA (see Section3.2). A 100g serving of intensively-reared pig meatprovides between 0.1mg and 0.3mg of vitamin E,which is equivalent to between 0.8% and 2.5% ofthe RDA.

Figure 10. Vitamin E content and percentage difference between pig meat from intensive andfree-range/organic systems.n.s. = difference not statistically significant.

Hoffmanet al(2003) report iron levels 213% higher in free-range pig meat compared with intensively-produced pig meat: 0.5mg and 0.16mg per 100g of lean meat respectively. This is equivalent to 3.6% of theRDA for a 100g serving of free-range pig meat compared with 1.1% of the RDA for a 100g serving ofintensively-reared pig meat (see Section 3.3).

vi. Based on a conversion factor of 0.910 to give total fatty acids in fat in lean pork (from MAFF, 1998).


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SUMMARY OF FINDINGS FOR PIG MEAT

There are no consistent differences in total intramuscular fat content between pig meat from free-range/organic systems and intensive systems;

Pig meat from free-range and organic systems has a higher proportion of omega-3 fatty acids and amore favourable (lower) ratio of omega-6 to omega-3 fatty acids compared with pig meat fromintensive systems, although the amounts would be expected to make only a relatively minorcontribution to dietary intake of omega-3 and the omega-6 to omega-3 ratio is relatively high in allsystems;

Free-range pig meat contains more vitamin E than intensively-reared pig meat, with up to 5% of theadult RDA in a 100g serving;

Free-range pig meat contains more iron than intensively-reared pig meat, with up to 3.5% of theadult RDA in a 100g serving.

4.5 Chicken meat

Total intramuscular fat content is generallybetween 8% and 49% lower for chicken meatfrom free-range and organic systems comparedwith indoor systems (two studies found nosignificant difference) (Fig. 11). Fat content ofchicken meat is also lower for slower-growing

genotypes compared with conventional fast-

growing genotypes (Fig. 12). Medium-growingstrains generally contain between 12% and 31%less fat than fast-growing strains (one studyshowed no significant difference). Slow-growingstrains generally contain between 17% and 67%less fat than fast-growing strains.

Figure 11. Intramuscular fat content and percentage difference between chicken meat fromvarious indoor and outdoor production systems.n.s. = difference not statistically significant. Chicken genotype indicated in parentheses as follows: F = fast-growing; M = medium-growing; S = slow-growing.


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Figure 12. Intramuscular fat content and percentage difference between meat from fast-,medium- and slow-growing chicken genotypes.n.s. = difference not statistically significant. Production system indicated in parentheses as follows: I = indoor;CI = conventional indoor; EI = extensive indoor; FR = free-range; O = organic.

The proportion of omega-3 fatty acids tends to behigher in chicken meat from free-range systemscompared with indoor systems but the differences

are not consistent across all studies. Several studiesreport a greater proportion of omega-3 fatty acidsin free-range systems but others report nosignificant difference and one study found a lowerproportion (Fig. 13). Castelliniet al(2002) foundsignificant differences between chicken meat fromorganic and indoor systems. On average, theproportion of omega-3 was 24% higher in thebreast meat of organic birds (5.3% vs 4.3%) and48% higher in the drumstick of organic birds(4.8% vs 3.2%) compared with intensively-rearedbirds.vii.

The proportion of omega-3 fatty acids also tendsto be higher in medium-growing strains comparedwith fast-growing strains but again the differencesare not consistent across all studies. Several studiesreport a greater proportion of omega-3 fatty acidsin medium-growing strains but others report nosignificant difference and one study found a lowerproportion (Fig. 14). Castelliniet al(2002) foundno significant difference in the proportion ofomega-3 between a fast-growing strain, amedium-growing strain and a slow-growing dual-purpose strain.vii.

However, the differences appear to be muchgreater for very slow-growing layer-type strains.Sirriet al(2011) found that a layer strain

contained double the proportion of omega-3 inthe breast meat and 48% more in the thigh meatcompared with a fast-growing strain (Fig. 14).Despite having 23% less fat, the breast meat ofthe layer strain contains over twice as much long-chain omega-3 as that of the fast-growing strain.The breast meat of the layer-type bird has 75mgomega-3 per 100g, of which 67mg is long-chainomega-3 (including 23mg of DHA). This compareswith 49mg/100g, including 31mg long-chain (with8mg DHA), for the fast-growing strain.viii. Meatchickens have been selected for both fastergrowth rate and higher meat yield, particularlybreast meat yield. These findings suggest thatbreeding meat chickens for one or both of thesetraits (even to a moderate extent as in dual-purpose birds) may have had a serious detrimentalimpact on the nutritional quality of the meat. Thisis likely to be, at least in part, a result of therelative inactivity of the birds selected for meattraits compared with layer-type birds.

vii. Data not presented in Fig. 13 because figures for shorter-chain omega-3 were not reported.viii. Based on a conversion factor of 0.945 to give total fatty acids in fat in poultry (from MAFF, 1998).


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Figure 13. Omega-3 content and percentage difference between chicken meat from variousindoor and outdoor production systems. The lower (darker shaded) section of each bar represents long-chain (20 carbons) omega-3. The upper (lighter shaded) section of each bar represents 18-carbon omega-3.n.s. = difference not statistically significant. Chicken genotype indicated in parentheses as follows: F = fast-growing; M = medium-growing.

Figure 14. Omega-3 content and percentage difference between meat from fast-, medium- andslow-growing chicken genotypes.The lower (darker shaded) section of each bar represents long-chain(20 carbons) omega-3. The upper (lighter shaded) section of each bar represents 18-carbon omega-3. n.s. =

difference not statistically significant. Production system indicated in parentheses as follows: I = indoor; CI =conventional indoor; EI = extensive indoor; FR = free-range; O = organic.


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Based on the findings of Sirri et al(2011)mentioned in the previous paragraph, in order toobtain the same amount of long-chain omega-3 aswould be found in a 100g serving of breast meatfrom a very slow-growing layer strain, a personwould have to consume more than twice thequantity of breast meat from a fast-growingstrain, which would involve consuming 2.7 times

the quantity of fat (Table 2). Similarly, a personwould have to consume around 38% more thighmeat of a fast-growing strain, which wouldinvolve consuming 2.2 times the quantity of fat(Table 2).

Table 2: Comparison of intramuscular fat and omega-3 levels in chicken meat from slow-growingand fast-growing strains reared organically. Based on Sirri et al(2011). For both meat types, totalintramuscular fat content was significantly higher for the fast-growing genotype (P


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26% higher (for breast and drumstick respectively)compared with birds reared indoors. Iron contentis between 55% and 58% higher for the breastmeat of slower-growing strains (a dual-purposeslow-growing strain and a medium-growing strain,respectively) (Fig. 15). No data were available for avery slow-growing layer-type strain or for thedrumstick meat of different strains.

A 100g serving of breast meat from a slower-growing bird reared organically provides around

0.65mg of iron, which is equivalent to 4.6% of theRDA (see Section 3.3). This compares with around0.35mg of iron in a 100g serving of breast meatfrom a fast-growing strain reared indoors, which isequivalent to 2.5% of the RDA. For the drumstick,a 100g serving from a fast-growing strain rearedorganically provides almost 0.8mg, which is 5.7%of the RDA, compared with around 0.6mg for an

indoor-reared bird, which is 4.3% of the RDA.

SUMMARY OF FINDINGS FOR CHICKEN MEAT

Free-range and organic chicken meat contains less intramuscular fat than intensively-reared chickenmeat;

Chicken meat from slower-growing strains contains less fat than that from fast-growing strains;

Free-range and organic chicken meat generally has a higher proportion of omega-3 fatty acidscompared with intensively-reared chicken meat, with a similar ratio of omega-6 to omega-3;

Chicken meat from medium-growing strains generally has a higher proportion of omega-3 fatty acidscompared with fast-growing strains, with a similar ratio of omega-6 to omega-3;

The meat of very slow-growing layer strains has a significantly higher proportion of omega-3compared with fast- and medium-growing strains, and the breast meat of these birds has a lowerratio of omega-6 to omega-3 and is particularly rich in long-chain omega-3, including DHA;

Levels of vitamin E are similar between chicken meat from free-range and intensive systems and arehigher in the meat of slower-growing strains compared with fast-growing strains, although thedifferences are relatively small;

Chicken meat from slower-growing strains and from birds reared organically contains more iron thanmeat from fast-growing strains and birds reared intensively, with higher welfare options providingaround 5-6% of the adult RDA in a 100g serving.

Figure 15. Iron content and percentage difference between chicken meat from indoor and organicsystems and from fast-, medium- and slow-growing genotypes at various slaughter ages.n.s. = difference not statistically significant.


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4.6 EggsTwo studies have found higher levels of fat in free-range eggs (Anderson, 2011; Pignoli et al, 2009).However, most studies have found no significant difference in total fat content between free-range andbattery eggs (Karstenet al, 2010; Hidalgoet al, 2008; Posadas Hernandezet al, 2005; Trziszkaet al, 2004).

Figure 16. Omega-3 content and percentage difference between eggs from battery cages andfree-range/organic systems.The lower (darker shaded) section of each bar represents long-chain (20carbons) omega-3. The upper (lighter shaded) section of each bar represents 18-carbon omega-3. n.s. =difference not statistically significant.

Most studies indicate the proportion of omega-3 is higher in free-range eggs compared withcage eggs, ranging from 26% to 170% more infree-range eggs (one study found no significantdifference and one study found a 10%reduction in free-range eggs) (Fig. 16).

Two of the studies in Fig. 16 provide thenecessary data to be able to calculate theactual amount of omega-3 in fresh egg yolk.ix

In the Karstenet al(2010) study, the amountsare equivalent to 8.6mg/g yolk in free-rangeeggs, of which 4.7mg is long-chain omega-3,compared with 3.2mg/g yolk in cage eggs, ofwhich 2.2mg is long-chain omega-3. In thePosadas-Hernandez et al(2005) study, theamounts are equivalent to 1.22mg/g yolk in

free-range eggs, of which 0.78mg is long-chainomega-3, compared with 1.16mg/g yolk in cageeggs, of which 0.75mg is long-chain omega-3.

In some cases, levels of omega-3 may be muchhigher in free-range eggs. For example,Simopoulos & Salem (1991)x report levels ofomega-3 in the yolk of Greek free-range eggsof 17.7mg/g, of which 10.6mg is long-chainomega-3 (including 6.6mg of DHA).

This is equivalent to 265mg of long-chainomega-3 (including 165mg of DHA) in a singleegg, making it an excellent terrestrial source oflong-chain omega-3, including DHA. These

hens fed on pasture that included a plant thatis particularly rich in omega-3 (purslane). Bycomparison, the same study found the yolk ofcage eggs purchased in the US contained1.7mg/g omega-3, including 1.2mg long-chainomega-3, equivalent to 30mg long-chainomega-3 in a single egg.

Most studies indicate that free-range eggshave a lower ratio of omega-6 to omega-3fatty acids compared with battery eggs(Karstenet al, 2010; Trziszkaet al, 2004; Lopez-Boteet al, 1998; Simopoulos & Salem, 1991).

Two studies found no significant difference(Pignoli et al, 2009; Hidalgo et al, 2008). Theomega-6 to omega-3 ratio is between 1.3 and14.1 for free-range and organic eggs andbetween 11.2 and 19.9 for battery cage eggs.

ix. Based on a conversion factor of 0.830 to give total fatty acids in fat in eggs (from MAFF, 1998).x. Data not presented in Fig. 16 because figures for omega-3 were reported in mg/g egg yolk rather than as a proportion of fattyacids and total fat contentment of the eggs was not reported to allow conversion.


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A number of studies have found higher levels ofvitamin E in free-range eggs compared with cageeggs. Karstenet al(2010) found twice the amountof vitamin E in free-range eggs, whilst Lopez-Boteet al(1998) found 31% more vitamin E in free-range eggs. However, others have found nosignificant difference (Anderson, 2011; Pignolietal, 2009). The quantities of vitamin E in egg are

significant in terms of human nutritionalrequirements (see Section 3.2). Lopez-Boteet al(1998) report that egg yolk contains 8.6mg and6.6mg per 100g for free-range and cage eggsrespectively. Assuming the contents of an

average egg weigh around 50g and that 35% ofthis is yolk (Ahnet al, 1997) this is equivalent to3mg per 100g (2 eggs) serving of free-range eggsand 2.3mg per 100g (2 eggs) serving of cage eggs.This is equivalent to 25% and 19% of the RDA,respectively. Andersonet al(2011) report thatfree-range eggs contain 281% more beta-carotenethan cage eggs. Also, Pignoliet al(2009) report

that free-range eggs contain 12% more luteinthan cage eggs.

No data were available to compare levels of ironbetween free-range/organic eggs and battery cageeggs.

Summary of findings for eggs:

There are no consistent differences in total fat content between eggs from free-range or organicsystems and eggs from battery cages;

Free-range and organic eggs generally have a higher proportion of omega-3 fatty acids and a morefavourable (lower) ratio of omega-6 to omega-3 compared with battery cage eggs;

Some free-range eggs are a particularly rich source of long-chain omega-3, including DHA;

Free-range eggs often contain more antioxidants (vitamin E, beta-carotene and lutein) comparedwith battery cage eggs and are a rich source of vitamin E.

Salmon and troutThe total fat content is generally between 38% and 60% lower in wild-caught salmon compared withfarmed salmon (two studies found no significant difference) (Fig. 17). The total fat content is generallybetween 23% and 82% lower in wild-caught trout compared with farmed trout (two studies found no

significant difference) (Fig. 18).

Figure 17. Total fat content and percentage difference between farmed and wild salmon.n.s. = difference not statistically significant.


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Figure 18. Total fat content and percentage difference between farmed and wild trout.n.s. = difference not statistically significant.

Both wild and farmed salmon are rich in long-chain omega-3 fatty acids and there are noconsistent differences in the proportion of omega-3 fatty acids between wild and farmed salmon.One study reports higher levels in farmed salmon

(Blanchet et al, 2005), whilst one study reportshigher levels in wild salmon (Cronin et al, 1991),and another reports no significant difference(although the proportion of DHA was significantlyhigher in the wild salmon in this study) (van Vlietand Katan, 1990). Long-chain omega-3 fatty acidsmake up between 16% and 28% of total fattyacids in farmed salmon and between 18% and24% in wild salmon (Blanchetet al, 2005; Croninet al, 1991; van Vilet and Katan, 1990).

Both wild and farmed trout are also rich in long-chain omega-3 fatty acids. However, theproportion of omega-3 fatty acids is between 43%and 66% higher in wild trout (Fig. 19).

The proportions of long-chain omega-3 in salmonand trout are equivalent to between 300mg and3000mg in a 100g serving of fish.xii Generally,between half and three-quarters of the long-chainomega-3 in salmon and trout is DHA, making it anexcellent source both of long-chain omega-3 ingeneral and DHA specifically.

xii Based on a conversion factor of 0.900 to give total fattyacids in fat in oily fish (from MAFF, 1998).

The ratio of omega-6 to omega-3 is relatively low(


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Figure 19. Omega-3 content and percentage difference between farmed and wild trout.

Figure 20. Ratio of omega-6 to omega-3 fatty acids and percentage difference between farmedand wild salmon.


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Figure 21. Ratio of omega-6 to omega-3 fatty acids and percentage difference between farmedand wild trout.n.s. = difference not statistically significant.

Summary of findings for salmon & trout:

Wild salmon and trout contain less fat than farmed salmon and trout;

Both wild and farmed salmon and trout contain a high proportion of omega-3 fatty acids and can

make a substantial contribution to meeting nutritional requirements for long-chain omega-3 fattyacids, including DHA;

Wild trout contains a higher proportion of omega-3 fatty acids compared with farmed trout;

All salmon and trout have a relatively low (generally


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the ratio of omega-6 to omega-3 is morefavourable (lower) in the higher-welfare products.For fish, the proportion of omega-3 is greater forwild trout compared with farmed trout and issimilar between wild and farmed salmon. For bothsalmon and trout, the ratio of omega-6 to omega-3 is lower for the wild fish compared with thefarmed fish.

The amounts of shorter-chain omega-3 in theanimal products examined are likely to make onlya relatively minor contribution to human dietaryintake, being generally below 100mg per 100g or100ml of product (except that some free-rangeeggs may have higher levels but still below 200mgper 100g of whole egg). For comparison, 100g ofwalnuts provides 7470mg of shorter chain omega-3 (ALA) (FSA, 2002).

For long-chain omega-3, several of the animal

products examined can make a substantialcontribution to meeting human nutritionalrequirements, particularly salmon and trout (bothwild and farmed), pasture-reared lamb and beef,higher-welfare chicken meat (especially from veryslow-growing layer-type strains) and some free-range eggs. Levels of long-chain omega-3 can befrom tens to hundreds of mg per 100g in theterrestrial products and from hundreds tothousands of mg per 100g in the fish.

In terms of DHA specifically, salmon and trout(both wild and farmed) contain substantialamounts of DHA, and some higher-welfare eggs,chicken and lamb also contain appreciableamounts.

AntioxidantsComparative data for vitamin E content areavailable for beef, milk, pig meat, chicken meatand eggs. Vitamin E levels are between 35% and160% higher for beef from pasture-based systemscompared with intensive systems, between 25%and 60% higher for milk from pasture-basedsystems compared with conventional systems and

generally between 25% and 200% higher for free-range pig meat compared with intensively-rearedpig meat. For chicken, there is no significantdifference in vitamin E content between chickenmeat from free-range and intensive systems andthe meat of slower-growing strains contains alittle (up to around 10%) more than fast-growingstrains. For eggs, some studies show between onethird and twice as much vitamin E in free-rangeeggs compared with cage eggs. However, in somestudies the difference is not significant.

The amount of vitamin E in a 100g serving ofhigher-welfare beef or pig meat is between 0.2mgand 0.6mg, which is equivalent to between 2%and 5% of the adult RDA, and would therefore beexpected to make a modest contribution tohuman dietary intake. The amount of vitamin E inmilk is lower (equivalent to around 0.5-1% of theadult RDA). The amount of vitamin E in free-range

eggs is around 3mg per 100g (2 eggs) serving. Thisis equivalent to around 25% of the RDA andwould therefore be expected to make a significantcontribution to human dietary intake. Forcomparison, 100g of walnuts provides around 4mgof vitamin E and 100g of almonds provides around24mg of vitamin E (Ibid.)

Comparative data for beta-carotene content areavailable for beef, milk and eggs. In most cases,levels of beta-carotene are several hundredpercent higher in the higher-welfare products.

However, the total amounts are relatively low interms of human dietary intake, being generallybelow 150g per 100g or 100ml of product, whichis equivalent to less than 1.5% of the adult RDAfor vitamin A. For comparison, 100g of raw carrotsprovides over 10 000g of beta-carotene (Ibid.),which is sufficient to provide 100% of the RDA forvitamin A.

IronComparative data for iron content are availablefor pig meat, chicken meat and trout. Iron levels

are over three times higher in free-range pig meatcompared with intensively-reared pig meat, over50% higher for meat from slower-growing chickenstrains compared with fast-growing strains,around 20-25% higher for organic chickencompared with intensively-reared chicken, andtwice as high for wild trout compared with farmedtrout.

The amount of iron in a 100g serving of thehigher-welfare products is between 0.5mg and0.8mg, equivalent to between 4% and 6% of theadult RDA, and would therefore be expected to

make a moderate contribution to human dietaryintake. For comparison, 100g of baked beanscontains 1.4mg of iron (Ibid.). However, much ofthe iron in animal products (between 30% and70%) is in the form of haem iron, which is moreeasily absorbed by the body (Strain and Cashman,2009). The absorption of non-haem iron fromplant sources is dependent to a large extent uponthe presence of facilitating and inhibitingsubstances in the meal and on the iron status ofthe individual (Ibid.).


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Table 3: Summary of nutritional differences between higher-welfare and lower-welfare animalproducts.The direction of arrows in the left hand column indicates whether a higher or lower value isgenerally considered beneficial. or indicate where higher-welfare products typically have a morefavourable nutritional composition (higher or lower levels respectively) compared with intensively-producedproducts. indicates no consistent difference between higher-welfare and lower-welfare products. -indicates no comparative data available.

Lamb Beef Milk Pig meat Chicken meat Eggs Salmon/ Trout

Total fat Pasture-based Slower-growing& free-range/organic

Wild

Proportionof omega-3

Pasture-based

Pasture-based

Pasture-based

Free-range/

organic

Slower-growing& free-range/

organic

Free-range/organic

Trout - wildSalmon

Proportionof long-

chainomega-3

Pasture-based

Pasture-based

Pasture-based

Free-range/

organic

Slower-growing& organic

Free-range/organic

Wild

Omega-6/Omega-3

ratio

Pasture-based

Pasture-based

Pasture-based

Free-range/

organic

Very slow-growing

Free-range/organic

Wild

Vitamin E

- Pasture-based

Pasture-based

Free-range

Slower-growing

Free-range -

Carotenoids

- Pasture-based

Pasture-based

- - Free-range -

Iron

- - - Free-range

Slower-growing& organic

- Trout - wildSalmon -

6. ConclusionsHigher-welfare animal products were shown to have a number of nutritional benefits over intensively-rearedanimal products.

Excessive fat consumption can contribute to weight gain and associated health problems. Higher-welfareanimal products are often significantly lower in fat than equivalent products from intensively-reared animals.This is true of pasture-reared beef, free-range and organic chicken and chicken of slower-growing breeds,and wild salmon and trout.

Choosing higher-welfare animal productsover intensively-reared animal productswould be expected to be beneficial inreducing dietary intake of fat, includingsaturated fat.

Modern western diets are often deficient inomega-3 fatty acids and have excessive amountsof omega-6 fatty acids relative to the amount ofomega-3. An adequate intake of long-chain (20carbon atoms) omega-3 fatty acids is particularlyimportant for brain and heart health. Comparedwith intensively-farmed animal products, higher-welfare animal products typically have higherlevels of omega-3 fatty acids and a morefavourable (lower) ratio of omega-6 to omega-3fatty acids. Wild salmon and trout, pasture-rearedlamb and beef, chicken meat from slow-growing

layer-type strains and some free-range eggs areparticularly beneficial in this respect.

Choosing higher-welfare animal productsover intensively-reared animal productswould be expected to make a substantialcontribution to meeting dietaryrequirements for long-chain omega-3 fattyacids and achieving a more balanced intake

of omega-6 and omega-3 fatty acids.

Higher-welfare animal products often containhigher levels of antioxidants, such as vitamin E andbeta-carotene, and higher levels of iron, comparedwith intensively-produced animal products.

Choosing higher-welfare animal productsover intensively-reared animal productswould be expected to make a moderatecontribution to meeting dietaryrequirements for vitamin E and iron.


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Limitations and further research

Issues with the dataDirect comparison of data between studies cannotnecessarily be made because of the widely varyingapproaches taken in the preparation of samplesand methodology of the nutrient analyses.

Therefore, whilst comparisons within a study arevalid, differences between one system or breed inone study and a different system or breed inanother study may not be. In some cases, studieswere excluded from the analysis because the datawere collected or presented in such a way that itwas not possible to find a common approach.

Within studies, comparison of data from differentsystems is often challenging because animals maymature at different rates. For example, cattlefinished at pasture generally take significantlylonger to reach slaughter weight than those

finished intensively. Similarly, chickens of slower-growing breeds will generally be significantlyolder at slaughter than their fast-growingcounterparts. Some studies compared animalsslaughtered at the same age, whilst otherscompared animals slaughtered at a similar weight.In many cases therefore, it is difficult to determinewhether differences in nutritional content are aresult of the system per se or a result of thediffering ages and/or weights of the animals beingcompared. Some studies compared bothcombinations of same age/different weight and

same weight/different age. In these cases, the datamost representative of commercial practice (i.e.usually the same weight) were used.

Issues with the production systemsThe actual level of welfare attained in anyproduction system is dependent not only on thewelfare potential of the production system butalso on the level of management skill applied to it.Since the studies used in this analysis did notmeasure welfare directly in the systems compared,the welfare potential of the systems is used as a

proxy for the level of welfare experienced by theanimals.

In some studies, the production systems are notclearly defined, which may partially masknutritional differences between systems. Forexample, several of the studies for milk comparedconventional retail or bulk milk with organic milk.Conventional milk may include milk from a rangeof systems, including those using grazing tovarying extents. The presence of milk frompasture-based systems in the samples ofconventional milk could potentially reduce

nutritional differences between these and theorganic milk samples.

Similarly, for studies comparing chicken fromslower-growing breeds with conventional fast-growing breeds, the actual and potential growthrate of the slower-growing strains is not alwaysclearly defined. A breed that may be considered

slow-growing

nutritional benefits of higher welfare animal products report sept

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