Investigating Opportunities Available in Genetic Selection for Healthy Beef

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Investigating Opportunities Available in Genetic
Selection for Healthy Beef

• J R Tait and James Reecy
• Iowa State University

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Product Branding
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Product Branding
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Fatty Acids

• Fatty acid concentrations determine healthfulness
  of the lipid
• Fatty acid concentration is influenced by
• Nutrition (Duckett et al., 1993)
• Breed (Pitchford et al., 2002)
• S. K. Duckett et al. 1993. J. Anim. Sci.
  712079-2088.
• W. S. Pitchford et al. 2002. J. Anim. Sci.
  802825-2832.

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Sample
Processing
Steaks from beef cattle
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Fatty Acid Synthesis and Modification
Fatty acid synthesis
160
180
140
161
181
141
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Atherogenic index
The atherogenic index as proposed by Ulbricht and
Southgate, 1991
Ulbricht, T.L.V., and D.A.T. Southgate. 1991.
Lancet 3388773
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Health Promoting Index
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Variation in Health-Promoting Index of Beef
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Variation in C140 Concentration of Beef
Number of Cattle
Percentage C140
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Variation in Iron Content of Beef
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Genetic Analysis

• Estimate h2 of fatty acids in Angus beef
• 140, myristic acid
• 141, myristoleic acid
• 160, palmitic acid
• 161, palmitoleic acid
• 180, stearic acid
• 181, oleic acid
• 182, linoleic acid

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Data Description

• Data collected from 2001-2004
• 916 Angus-sired bulls and steers
• 87 sires with 1 to 41 progeny
• Calf-fed management
• Corn-based finishing rations

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Data Description

• Longissimus dorsi sample
• External connective tissue was removed
• Fatty acids evaluated by gas chromatography

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Data Descriptors
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Genetic Analysis

• MTDFREML
• Sire model
• Contemporary group definition
• Herd of origin
• Sex
• Feedlot management treatment
• Harvest date

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Genetic Analysis

• Model
• Y Xb Zu e
• Fixed effects (b)
• Model I Contemporary group only
• Model II Cont group lipid covariate
• Random effects (u e)
• Sire
• Error

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Heritability Estimates ( of lipid)
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Heritability Estimates ( of lipid)
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Heritability Estimates ( of lipid)
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Discussion

• Generally, little change in h2 estimates with
  Model II
• Short-chain, saturated fatty acids are heritable
• 140 (0.49)
• 160 (0.43)
• Monounsaturated fatty acids are heritable
• 161 (0.49)
• 181 (0.38)

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Genetic Correlation Estimates
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Conclusions

• Opportunities exist to select for fatty acid
  composition of beef
• Genetic correlations?
• Fatty acid relationships to consumer
  acceptability need to be investigated

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Where do we go from here?

• Genetic variability exists for fatty acids
• Very expensive traits to measure
• Are there other characteristics which make beef
  healthful to consumers?
• Jan. 2008 release of BovineSNP50

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Where do we go from here?

• Iowa State University, in collaboration with
  NBCEC, proposed a Healthfulness of Beef study
  utilizing the BovineSNP50
• Discovery and Validation both in the experimental
  design
• Pfizer Animal Genetics chose to invest in this
  project and vision for the beef industry

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Management
National Cow Herd
Bulls and/or Genotypes with Superior Genetic
Merit for Beef Healthfulness
EPDs/DNA Markers
Beef Cattle Seed Stock Populations
Selection
Longissimus Dorsi Samples
Collection of
Collection of
Collection of
Tenderness / Taste Data
Carcass Data
Nutrient Composition Data
Used for
Used for
Used for
Genetic Evaluation
Develop Guidelines for Selection of New Breeding
Stock
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Acknowledgements

• ISU Center for Designing Foods to Improve
  Nutrition
• ISU Burroughs Endowment
• National Cattlemens Beef Assoc.
• U.S. Meat Animal Research Center
• NBCEC National Beef Cattle Evaluation
  Consortium
• Pfizer Animal Genetics
• Jim Reecy Research Group Mary Sue Mayes, Matt
  Schneider
• Don Beitz Research Group Travis Knight, Shu
  Zhang, Jon Schoonmaker, Grace Duan, Matt ONeil
• Dorian Garrick
• Rohan Fernando