Adaptation in Beef Cattle

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Adaptation in Beef Cattle T. G. Jenkins Meat Ani
mal Research Center
Clay Center NE
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ADAPTABILITY Frequently a focus of discussion b
ut are we all discussing the same concept?

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Objectives 1. What is meant by Adaptability
2. Evidence of Adaptability in beef cattle
3. Potential for application

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Terminology Phenotype the appearance of an
individual resulting from the
interaction of genotype and
environment Genotype total sum of all genetic
factors of an individual
Environment all factors that
influence the expression of genes
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Types of Adaptability Evolutionary Trans-gener
ational Phenotypic adjustments made by in
dividual within a lifetime may be linked to bio
logical processes that are evolutionary
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ADAPTABILITY-
Evolutionary - Provides a species the ability f
or continued existence (trans-generational)
adaptability could be considered an
optimization of a phenotype to express
fecundity potential
What creates a need for the organism to change?
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Changes in conditions in which affects the
expression of the fecundity potential of species
Environment geographic location foo
d resources climatic conditions pathogens
etc

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What allows the species to change
Genetic variability Individuals exist
within a population whose genotype provides a
selective advantage in the altered environment
allowing these individuals to leave greater
number of offspring
mutations
existing alleles
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Existing alleles (Mayr, 1970) In manufacturing d
istricts of England moth change color from white
to black because of pollution. Predators were
able to see white moths so black had selective
advantage
Mutation (Nature Biotech, Feb, 1999)
Specific strains of Salmonella have become
resistant to antibiotics (Amoxicillin,
Flofenicol, Streptomycin, Tetracycline)
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Phenotypes vary because genetic variation exists
in population that enable forces of change
(environment) to alter genotypic frequencies
Selection
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Evidence for adaptation in beef cattle
Geographic location Ngunni in Africa tsetse fl
y Bonsmara Animals that suffer from hyperthermi
e have an increased respiratory and pulse rate
with concomitant metabolic, physiological and
endocrinological disturbances. Head shape
Breeds foundation phase frequently
associated with geographic location, enhance
frequency of alleles of favored phenotypes
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Effecting genetic change may or may not lead to
alleviation of environmental constraint.
Failure Composite population in Venezuela (all ma
de using 50 Zebu and 50 unadapted Bos
taurus breeds) appeared to have failed to
produce productive cattle in spite of strong
selection. 
Success Australian milking zebu (AM
Z) Pakistani Sahiwal and Red Sindhi dairy
cattle were mated initially to high- producing
Jersey cattle. Later, some infusion of Illawarra,
Guernsey and Holstein-Friesian bloodlines
occurred. Adaptation for heat tolerance and
tick resistance in bred for milk production.
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• Texas Longhorn
• Why did this particular Creole type flourish in
  hostile nutritionally sparse environment?

Resistant to tick fever
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Brisket Disease is caused primarily by an oxygen
shortage oxygen availability is 17 less at
5,000 feet than it is at sea level 20 less at
6,000 feet, 26 less at 8,000 feet, and 31 less
at 10,000 feet. Cause excessive heart activity,
eventually, the heart wears out and stops
beating. The losses from the disease can vary dep
ending on the origin of the cattle. In cattle
born and raised at high elevations, the losses
tend to run from .5 to 5. In imported or
lowland cattle the losses can range from 30 to
40. There is test to identify animals that are r
esistant, moderately heritable, selection
practiced to resolve
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Breeds reproduction at low Levels of Dry Matter
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Potential applications of Adaptability in Beef
Cattle Production
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Forage selectivity
Parasite resistance
Endophyte resistance
Heat resistance
Water needs
Nutrient use
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What is required to implement Adaptability to
improve beef production
Recognition of novel phenotypes associated with
economically important traits Determination if ph
enotype can be measured accurately
Assessment of variation associated with
phenotype Proportion of variation attributable to
genetics Programs to implement change