Genetic engineering can be the direct manipulation
of an organisms genome using biotechnology or the
indirect modification through artificial selection
This essay will discuss the most relavent aspects of genetic
engineering and assess the benefits, limitations and concerns of using
genetic engineering to improve animal, health, disease defence
Firstly the previous methods of genetic engineer ing will be initially discussed,
moving on to the current available biotechnologies and finally consider the
future potential of these technologies
Selective Breeding
Selective breeding has been used for over 2000 years to select animals with desired traits based on
phenotypic expression,
Improve Health
Breeding to produce homozygosity of desired traits
Foot angle to reduce lameness
"NZ" style easycare systems
Sheep
Foot rot
Worms
Desireable traits
Dairy cows are typical example of selective breeding
with highest yielding cows bred to high yield
(daughter) producing bulls
Benefits
More yield per cow (profitable)
Environmental/ feed the world/less cows required
Negatives
Irresponsible selection
Deleterious traits
Lameness
Poor fertility
Nutrient partitioning
Maybe inadvertedly selecting for deleterious triats
Increased production
FCR
Fertility
Growth
AI/MOET
Increase selection intensity
Spread genes worldwide rapidly
Cover more animals
Reduce population variance
Gene Identification
Genes can now be identified to detect deleterious genes
1) Gene code identified e.g. Mastitis suceptibility
2) Opposite code created and marked with flourescence
3) Code binds at site of gene if present
Genomics allows selection of more suitable parents
Select against weaknesses
Reduce inbreeding
Avoid homozygosity of traits and genes
e.g. halothane gene in pigs
Porcine Stress syndrome
Sudden death
Pale soft exudative meat
Acid meat from anaerobic muscle
etabolism decreasing muscle quality
Back muscle necrosis
Reduce generation gap in cows
More rapid prduction of offspring
Genetic engineering
Genetic engineering is the process of changing the
phenotype through expression of introduced DNA,
addition, deletion or substitution of the animals own
DNA
Techniques used
Pro-nuclear micro injection
Inject genetic material into the nucleus of oocyte
Over expression
If not icorporated into germline it wont be
passed to next generation