Science & Technology in Action

8th Edition

Bovine Genomics


Agricultural Science
This lesson explains what is meant by genomics and outlines how genomic data is used to improve the quality of livestock.
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Lesson excerpt

Livestock species play a major role in economic development worldwide. Until recently selecting animals for breeding was done by personal judgement and observation of phenotypes or of pedigree data. In this way people have been guiding the evolution of domestic animals for about ten thousand years. This method has been quite successful but there have been some drawbacks; e.g. in dairy cattle increased milk yield has been accompanied by a decrease in reproductive efficiency. With the advent of genomics, our increased knowledge should lead to marked improvements in performance in both milk yield and reproductive efficiency, as well as many other features.

Biological processes that influence performance
The performance of cattle is influenced by a wide variety of factors and is a prime example of the nature versus nurture debate: a beef animal may have the genes for large muscles (nature) but if it is not fed properly (nurture) it will not have a high live-weight gain. 

Hormone levels are also important as they control the growth, development and productivity of all animals. Prolactin and oxytocin are important in the control of milk production, while growth hormone affects live-weight gain. Hormones are of course genetically determined. The use of artificial growth promoters is now banned in the European Union.

If animals have a disease they will not perform at optimum levels and it has been shown that routinely dosing cattle with antibiotics increases their live-weight gain.


True or False?

  1. As milk yield has been improved all other features have also improved. false
  2. Selection of animals for breeding is an exact science. false
  3. A cow with genes for good milk production will not always produce lots of milk. true
  4. Genetic gain means giving cattle more genes. false
  5. Autosomes are sex chromosomes. false
  6. Cattle and humans have about 2/3 of their DNA in common. true
  7. Gut flora are the symbiotic micro-organisms found in the intestines. true
  8. The genome includes all the DNA of a species. true
  9. Bovine centromeres occur in a different region of the chromosomes from those of humans. true
  10. Animals selected for breeding after studying their genome are not classed as “genetically modified”. true
  11. The ICBF keeps data from only one source. false
  12. Quantitative traits vary in degree from animal to animal. true
  13. Modifier genes change the location of other genes. false
  14. Teagasc carries out research into cattle breeding. true
  15. The diploid number of humans and cattle is the same. false

Glossary of terms

Ancestry data
genetic gain
genetic data
genetically modified
gut flora