Adaptation in Beef Cattle

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Adaptation in Beef Cattle T. G. Jenkins Meat
Animal Research Center Clay Center NE
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ADAPTABILITY Frequently a focus of discussion
but 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-generational Phenotypic adjustments
made by individual within a lifetime may be
linked to biological processes that are
evolutionary
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ADAPTABILITY-
Evolutionary - Provides a species the ability
for continued existence (trans-generational) a
daptability 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 food
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
districts 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 fly Bonsmara Animals that suffer from
hyperthermie 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
made 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
(AMZ) 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
depending 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
resistant, 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
phenotype can be measured accurately Assessment
of variation associated with phenotype Proportion
of variation attributable to genetics Programs to
implement change