Benefits of forage systems on product quality: mechanisms and implications

Kevin J. Shingfield

kes14@aber.ac.uk

Ruminant foods: Food choices, health and environmental impact

• Desirable products• High biological value protein• Source of bioactive lipids • Rich in micronutrients

• Rich in saturates• Contain trans fatty acids• Environmental footprint

Impact of grazing on nutritional value

• Increase carotenoids/tocopherols• Enrich PUFA (18:3 n-3) • Elevate cis-9, trans-11 CLA• Lower 12:0, 14:0 and 16:0

• Increase carotenoids/tocopherols• Lower n-6/n-3 PUFA ratio• Increase 18:3/20:5/22:6 n-3• Elevate cis-9, trans-11 CLA

Incidence of chronic human diseases

• Coronary heart and cerebrovascular disease is the leading

cause of death worldwide

• 80% of the burden now occurring in developing countries

Direct and indirect costs of CVD per annum

• EU25 € 200bn (Allender et al., 2008)

• US $ 403bn (Thom et al., 2006)

• India $ 237bn (International Heart Summit, 2011)

trans fatty acids and health

• trans fatty acids increase in coronary heart disease risk(Willett et al., 1993; Kromhout et al., 1995; Ascherio et al.,1999)

• trans fatty acids increase LDL but lower HDL cholesterol andelevate total:HDL cholesterol ratios (Mozaffarian et al.,2006)

• trans fatty acids elevate plasma TAG (Mensink et al., 2003),Lp(a) lipoprotein (Ascheiro et al., 1999) and decrease meanLDL particle size (Mauger et al., 2003)

• Possible role of trans fatty acids in inflammation which is arisk factor for atherosclerosis and sudden cardiac arrest(Mozaffarian et al., 2006)

• CLA inhibits chemically induced mouse epidermal tumours

(Ha et al., 1987)

• CLA inhibits chemically induced forestomach neoplasia in

mice (Ha et al., 1990)

• CLA protects against abberant crypt foci formation in the rat

colon (Liew et al., 1995)

• CLA shown to be a potent anticarcinogen in the mammary

model of cancer in rats (Ip et al., 1991; 1994; 1999)

cis-9, trans-11 CLA and health

Long chain n-3 fatty acids and health

• Lower cardiovascular disease risk

• Anti-arrhythmic effects on heart muscle

• Improve arterial plaque stability

• Anti-thrombotic properties

• Lower endothelial activation

• Role in infant brain and retina function

• Positive effect on immune function

Ruxton et al., 2005

Effect of grazing: Mechanisms

Mouth

Abomasum

Dietary Lipid

18:2n-6 and 18:3n-3

CLA and CLNA

trans 18:1

18:0

LipolysisB

ioh

ydro

gen

ati

on

Ruminal lipolysis and biohydrogenation

18:3 n-3 92%

18:2 n-6 86%

Ingested plant cellsFrommouth Abomasum

Organelle phospho- & galacto lipid

Free fatty acids

Organelle phospho- & galacto lipid

Intact cell Ruptured cell

Rumen microflora

Bacterial lipolysis

Free Pool C18 PUFA

Conjugated dienes and trienes

Trans monoenes

18:0

Protozoa

Green odour compounds

Plant lipolysis

Rumen

Fresh forage: Possible mode of action

Lee et al., 2007; Huws et al., 2011, 2012

Esterified lipidTrans FFAPUFA

Ruminal protozoa are rich in polyunsaturated fatty

acids due to ingestion of chloroplasts

Scale bars – 20 µmEpidinium sp. isolated from the rumen of steers fed fresh grass

Huws et al. (2009). FEMS Microbiology Ecology, 69: 461-471. Huws et al., 2009

Distribution of trans 18:1 isomers

0.28 0.24 1.03 3.02 3.8

49.4

10.2

17.6

6.9 7.5

0

10

20

30

40

50

60

4 5 6-8 9 10 11 12 13/14 15 16

(%)

Double bond position

Pasture (Beef muscle)

0.2 0.2

14.717.3

21.720.3

14 13.6

3 2.3

0

5

10

15

20

25

4 5 6-8 9 10 11 12 13/14 15 16

(%)

Hydrogenated oil

Stender and Dyerberg, 2003; Dannenberger et al., 2004

Shingfield and Wallace, 2014

Synthesis of CLA in ruminants

Effect of grazing: Implications

Breeding for improved product quality

Breeding: combining novel characteristics with an existing set of required traits

Enhancing the positive characteristics of grazing on the nutritive value of ruminant foods

• Grass breedingSelection for the proportions of 18:3n-3 and/or tocopherolsProduction of higher lipid varieties

• Rumen microbiologyDevelopment of targeted anti-microbial agentsTesting of aldehydes and volatile components

• Animal breedingOptimising animal genetics for grazingSelection of animals with higher desaturase activity and/or lower activity of enzymes involved in de novo fatty acid synthesisDeveloping proxy traits for ruminal lipolysis and/or biohydrogenation

Thank you for your attention