Improving the health and

healthfulness of beef

J.M. Reecy, and D.C. Beitz

Iowa State University

Overview

• Disease resistance– Infectious Bovine Keratoconjunctavitus– Respiratory Disease

• Improving the Healthfulness of Beef

Pink Eye• Reported in the USA since 1889

• 45% of Missouri herds have endemic IBK

• Average prevalence = 8%

• More common in the young – 10-60%

• Immunity develops with age

• No gender affinity

What Causes “Pink Eye”• Moraxella bovis• Brannamella ovis?• High UV light• Dust• IBR infection• IBR vaccination• Mycoplasma infection Mycoplasma bovoculi• Trauma• Face flies- Musca autumnalis (since 1946)

Options For Control/ Prevention

• Are the technologies up to the job?

Options For Control/ Prevention

• Not up to the job–Vaccines–Fly control–Dust control–Pasture clipping

What are the Future Options

• Genetic selection

• Improved vaccines

• Better treatment

Requirements of the project• Serve as a model for disease

resistance/susceptibility research– Internal parasites - nematodes– Respiratory

• Use field records– Need to develop data collection scheme

Data Collection

• Two seasons–When cases are actively

observed–Weaning

• Scoring system• Data sheets

Score 2 – An active lesion involving one-third to two-thirds of the cornea.

Score 1 – An active lesion involving less than one-third of the cornea.

Score 4 – An active lesion with perforation of the cornea

Score 3 – An active lesion involving more than two-thirds of the cornea.

Percent of Infection per Eye

01020304050

Left Right Bilateral

Pinkeye Data Analysis1823 head (Indiana, Iowa, Missouri, Wisconsin)

HeritabilityMTDFREMLModel Y = + CG +animal +PE + error

• CG = Sex-weaning group (4)• PE = permanent environmental

h2 = 0.18

Effect of Pinkeye on Weaning Weight

440

450

460

470

480

490

500

Infected Non-Infected

lb

Effect of Pinkeye/Corneal Abrasion on Weaning Weight

Wea

ning

Wei

ght (

Lbs

)

Additional Results

No evidence of prior exposure to bovine rhinotracheitis as having an effect

No evidence of Carrier status (M. bovis and B. Ovis) effecting incidence

Tear Film

Lipid layer: Reduces evaporation , prevents contamination

Aqueous layer: Lubrication and protection

Mucus layer: Lubricates and protect the cornea.

Ocular defense factors affecting susceptibility

sIgA and Lactoferrin (Lf) as candidate factors in the tear film influencing susceptibility

Antigen binding: protection against invading microorganisms

Hypothesis: Cattle susceptible to pink eye produce higher levels of sIgA and lower Lf

IgA Levels in Bovine Tears

400450500550600650

Healthy Infected

ng/ml

IGA levels and probability of infection

0.00.20.40.60.81.01.2

0100 200 300 400 500 600 700 800

IgA levels

Predicted

Mean

Prob

abili

ty o

f Cor

neal

Sca

rrin

g

MARC Pinkeye data

Gary Snowder (JAS 2005 83(3):507-18. )19 years of data

Calves listed as being treated in the herd book

Number of records907 to 10,947 head per breed1.3 to 22.4% incidence

Breed N Incidence h2

Angus 6,347 3.7 0.25Hereford 4,579 22.4 0.28Red Poll 998 3.1 0.09Charolais 2,878 6.5 0.00Simmental 1,775 7.6 0.10Limousin 961 3.4 0.11Gelbvieh 2,391 2.1 0.05Pinzgauer 908 1.3 0.02Braunvieh 907 1.8 0.12MARC I 4,336 3.9 0.03MARC III 10,947 5.9 0.26

PREVALENCE BIK HEREFORD AND ALL OTHERS

0

10

20

30

40

50

60

70

1983 1986 1989 1992 1995 1998 2001

Respiratory Disease

• Bovine Respiratory Disease is the most common and costly disease in the U.S.

• National mortality rate for bovine respiratory disease is 6% (NAHMS, 1997)

• Lung lesions are routinely observed in animals that exhibited no clinical signs

Respiratory Disease

•Use field records–Need to develop data collection scheme

–Treatment data

–Lung Score

Designing Beef to Produce a Healthier Product

Overview• Goal of Research

– Develop the tools to allow breeders to select for healthier beef

• What does this mean to the beef industry?– It will be able to actively address human

health concerns with respect to consumption of beef

Interaction of Genetics and Environment in Causing

Human DiseasePRIMARILY NURTURE(Environment)

PRIMARILY NATURE(Genetics)

Motor vehicle accidents

Heart Disease

Stroke

Pneumonia, influenza

Nutritional deficiencies, nutritional anemias

Cirrhosis of the liver

Lung cancer

Osteoporosis

Diabetes

Obesity

Colon cancer

Breast cancer

Dwarfism

Two Leading Causes of Human Deaths in the U.S.

Cause of death Rank1 Deaths PercentageAll causes --- 2,443,387 100.0Diseases of heart 1 696,947 28.5Malignant neoplasms 2 557,271 22.8Cerebrovascular diseases 3 162,672 6.7Chronic lower respiratory distress 4 124,816 5.1Accidents (unintentional injuries) 5 106,742 4.4Diabetes mellitus 6 73,249 3.0Influenza and pneumonia 7 65,681 2.7Alzheimer’s disease 8 58,866 2.4Nephritis, nephrotic syndrome, and nephrosis 9 40,974 1.7Septicemia 10 33,865 1.4

1Rank based on number of deaths; total = 79% of all deaths.Source: National Vital Statistics Report, Vol. 15, No. 17

Obesity in U.S. in 2004BMI > 30, or ~ 30 lbs. overweight for 5'4" person

2004

                                                                                                                                                                                                                                                                                                

Calories from Fat

SFA MUFA PUFA

An Average American Diet 34% 16% 11% 7%

What are Americans

eating?

Calories from Fat

SFA MUFA PUFA

American Heart Association Step I Diet

30% 9% 14% 7%

American Heart Association Step II Diet

25% 7% 12% 6%

What should Americans be eating?

How Do We Name Fatty Acids?• Carbon chain length and # of

unsaturated bonds (e.g. 18:0 or 18:1) • Name

• Palmitic (16:0) or Palmitoleic (16:1)9

• Stearic (18:0) or Oleic (18:1) 9

• Linoleic (18:2) 9,12

Atherogenic index

The atherogenic index as proposed by Ulbricht and Southgate, 1991

= (MUFAs) + (PUFAs)12:0 + 4*(14:0) + 16:0

Health Promoting Index

=(MUFAs) + (PUFAs)12:0 + 4*(14:0) + 16:0

How Does Beef Compare to Other Sources of Fat?

Health-promoting index of several foods

Soy oil 7.69Olive oil 7.14Beef PL(Knight) 3.03Chicken 2.27Pork 2.13Lard 1.92Beef(Eichhorn) 1.67Margarine 1.61Beef(Knight) 1.52Beef(Garret) 1.49

Food HPI

Beef(NLMB) 1.43Beef TG(Knight) 1.27“Extreme” milk fat 1.30Beef(Beitz) 1.16Tallow 1.12“Greatest” milk 0.94“Average” milk fat 0.44“Low” milk fat 0.30Palm kernel oil 0.15Coconut oil 0.06

Food HPI

Environment

Genotype

Phenotype

Feeding systems affecting fatty acid composition

Ruminant species

- Rumen biohydrogenation

- Forage increases reductive potential of the rumen

- Rumen can be overloaded with PUFA (CLA increase in pasture-fed cattle)

16:0 18:0

16:1 18:1

Fatty acid synthesis

14:1

14:0

Fatty Acid Synthesis and Modification

Triacylglcyerols PhospholipidsSample

Processing974 Steaks

from beef cattle

Statistical analysis• Steers and bulls slaughtered at normal

finishing weight.

• Contemporary groups based on year, farm of origin, feedlot, and harvest date.

• 63 contemporary groups (1-65 cattle per group).

• 77 sires (1-40 progeny per sire).

Variation in Health-Promoting Index

of Beef

1 2 3 4 50

25

50

75

100

125

150

175

Number of Cattle

Health-Promoting Index

Phospholipid Composite Triacylglycerol

Fatty Acids Average (wt%) Heritability

14:0 2.81 0.39 ± 0.21

16:0 26.28 0.40 ± 0.21

16:1 3.35 0.54 ± 0.24

18:0 3.35 0.27 ± 0.19

18:1 41.05 0.33 ± 0.20

18:2 7.46 0.23 ± 0.18

CompositeFatty Acid Composition

Index Average Heritability Extreme EPD (-)

Extreme EPD (+)

AI 0.66 0.45 ± 0.22 -5.70 8.36

16:1/16:0 0.13 0.44 ± 0.22 -6.77 6.92

18:1/18:0 3.25 0.30 ± 0.19 - -

X:1/X:0 1.14 0.37 ± 0.21 - -

16:0/14:0 9.62 0.10 ± 0.14 - -

18:0/16:0 0.49 0.34 ± 0.20 - -

Composite Fatty Acid Indexes

Does Breed to Breed Variation Exist in Fatty

Acid Composition• Collaborative project with Larry Cundiff at

Meat Animal Research Center• 588 animals

– Sire Lines• Angus BeefMaster• Hereford Bonsmara• Brangus Romosinuano

– Dam Lines• Angus MARC III

Fatty Acid Low High P-value14:0 3.40 3.96 <.0001

16:0 27.18 29.38 <.0001

16:1 3.47 3.78 0.0075

18:0 12.51 14.31 <.0001

18:1 33. 90 35.73 <.0001

18:2 1.51 1.87 0.0007

Significant Differences in Fatty Acid Composition

Exist Between Breeds

Index Low High P-valueAI 0.87 1.01 <.0001

16:1/16:0 12.51 13.78 <.0001

18:1/18:0 240.05 274.77 <.0001

x:1/x:0 88.07 96.41 <.0001

16/14 706.97 802.43 <.0001

18/16 43.49 51.34 <.0001

Significant Differences in Fatty Acid Indexes

Exist Between Breeds

Index Low High P-value18:1t11 4.49 6.17 0.0016

18:1c11 1.05 1.25 <.0001

18:3n3 0.20 0.24 <.0001

CLAc9,t11 0.35 0.42 0.0133

22:5n3 0.16 0.25 0.0378

22:6n3 0.02 0.03 0.0073

Significant Differences in Fatty Acids

Exist Between Breeds

New Compounds• Conjugated Linoleic Acid

– Anti-cancer, anti-obesity, anti-diabetic• Heme and non-Heme Iron

– correlated positively with hematological status • Spingolipids

– may inhibit colon cancer in humans • Creatine

– improves muscle strength • Vitamin E

– negatively correlated with risk of prostate cancer

Are Single Nucleotide Polymorphisms Associated

with Fatty Acid Composition• 172 purebred American Angus Bulls and Steers ISU

Meat Quality Selection Herd• Stearoyl-CoA Desaturease SNPs

– Enzyme responsible for desaturating fatty acids– SCD 316, SCD536, SCD1278

Amino Acid Genotype # Animals Percentage

VV CC 115 67

VA CT 57 33

Effect of a Stearoyl-CoA Desaturase

DNA polymorphism

Lipid

16:1/16:0

P-ValueVA VV

Phospholipid 6.3% 6.8% 0.13

TAG 14.5% 13.9% 0.02

Summary• Triacylglycerol fatty acid composition is more

heritable than phospholipid fatty acid composition.

• Fatty acid desaturation is more heritable in beef cattle than is fatty acid elongation.

• Health Promoting index/AI is highly heritable.

• Differences in fatty acid composition exist between breeds.

• DNA markers can be used to identify more healthful beef.

Conclusions

Fatty acid composition is a heritable trait.

Lipid composition can be improved with respect to human health by genetic selection.

Where Do We Go From Here?

1) Obtain Research Funding

2) Develop resource populations• American Angus (have in hand)• Meat Animal Research Center

3) Correlation With Other Traits

4) Identify Molecular Markers

Where Do We Go From Here?

5) Human Studies• Taste Test Panels • Feeding Studies

6) Identification of Novel Health Compounds

7) Development of New Analytical Techniques

Acknowledgements•National Beef Cattle Evaluation Consortium

•USDA Center for Designing Foods to Improve Nutrition at the Iowa State University

•The Wise and Hellen Burroughs Endowment

•National Cattleman’s Beef Association

•Collaborators