PDST Agricultural Science Support
On Farm Genetics
Séamus Hynes
Gairmscoil Mhuire
Genetics has been treated inadequately in the past in our
practical component as it has been approached as an isolated
topic. There has been little scope to do simple experiments in the
laboratory which are directly related to agricultural science.
Genetics is the corner stone on which all advances are made
in animal and crop production. It is at the forefront right now in
research, which is striving to make an agricultural based
enterprise profitable and, on a global scale, to feed an ever
increasing world population.
There is great scope in our practical component to inculcate
genetics into our animal or crop presentation. It will enable the
student to demonstrate a better knowledge of their on-farm
experience and to fully engage in the advances being made in
productivity. An important reason for culling is to upgrade a herd.
Research in genetics on a farm by farm basis has the cumulative
effect of upgrading our national herd in dairy, beef, sheep, pigs,
poultry and indeed crops. The following examples demonstrate
the relevance of genetics in various enterprises.
P1
PDST Agricultural Science Support
1. The Dairy Enterprise
Holstein Friesian
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Bigger Frame (600kg)
Produce more gallons/year
Consume more feed
Up to 25% fertility problems
New Zealand Jersey
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Hardier
More Fertile
More Placid
P2
PDST Agricultural Science Support
Jersey X Friesian Cross
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Hybrid vigour (+ 14-15%)
Much more fertile (infertility ~10%)
50% calf down in 18-20 days
Hardier and versatile
Consumes less feed (5 can be feed with the same amount of food as 4
Holsteins = more profit)
Notice the difference between the size of the frame in these two calves
P3
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EBI (Economic Breeding Index)
Calculated as follows (approx) –
 38% Productivity
 35% Fertility
 10% Calving (difficulty, dead/alive)
 7% Beef
 6% Maintenance
 4% Health (lameness, SCC)
P4
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2. The Beef Enterprise
Friesian Cow
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Black and White
Good milk yield
Hereford Bull
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Red
Beef strain
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Hereford X Friesian Cross
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Phenotype – Black White head
Good heifers – will be suitable for replacement cows as their milk
yield would be more than adequate to feed newborn calves
Bullocks and poorer heifers can be feed for slaughter because of
their beef strain
Beef –Single Suckler
Simmental Cow
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Superior milk
Good fertility
Early puberty and ease of calving
P6
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Charolais Bull
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Good live weight gain
Superior carcass weight
Grade well when slaughtered (EURO)
Simmental X Charolais Cross
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Hybrid vigour
Excellent growth rate
Good carcass and perform well for slaughter
P7
PDST Agricultural Science Support
Genetic Mutations in Beef
Enterprise
Mutation – Any heritable change in the genetic material, not caused by
genetic segregation or recombination, which is passed on to
succeeding generations
1.
Belgian Bull cattle
Doubling of muscle due to mutation of the myostatin gene
2.
BLAD – Bovine Leukocyte Adhesion Deficiency
Genetic defect affecting white blood cell function which causes
extreme susceptibility to infection.
P8
PDST Agricultural Science Support
3. The Sheep Enterprise
Belclare
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Highly prolific
Good conformation
Produce good mothers
Higher level of resistance to intestinal parasites
Scottish Blackface ewe
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Excellent mothers
Hardy and small
Lower maintenance
Lower prolificacy than Belclare breed
P9
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Belclare X Scottish Blackface Cross
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Hybrid Vigour
Highly prolific (>70% of ewes will produce twins)
Excellent mothers
Hardy
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Mule (Bluefaced Leicester Ram X
Scottish Blackface Ewe)
Bluefaced Leicester Ram
Scottish Blackface Ewe
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PDST Agricultural Science Support
Mule (Bluefaced Leicester Ram X Scottish Blackface Ewe)
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Highly prolific (>60% will produce twins)
Excellent Mothers
Hardy Breed
Hybrid Vigour
Poorer conformation than Belclare X Blackface
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PDST Agricultural Science Support
4. The Pig Enterprise - Organic
Large White Male
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Good Conformation
Highly Prolific
Fast Growth
Good Meat Quality
Good FCR
Saddle Back female
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Slow Maturing
Good Taste
Maternal Traits
Hardy
P 13
PDST Agricultural Science Support
Large White X Saddle Back Cross
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Slow Maturing
Hybrid Vigour
Hardy
Maternal Traits
High Meat Yield
Excellent Taste
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PDST Agricultural Science Support
5. The Poultry Enterprise
i66 Male
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Light Red Feathers
White shanks, beak and skins
JA57 Female
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2.2 kg as adult weight
Red Feathers
Yellow shanks, beak and skin
Offspring – i657
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Tastier
Slower maturing bird
More agile
Good leg conformation
P 15
PDST Agricultural Science Support
6. Plant Genetics -Effect of the environment
on phenotype
Cress Seeds
1.
2.
3.
4.
Place moist filter paper in 3 petri dishes
Place cress seeds in each
Place in dark box
Allow them to germinate
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Result – they germinate but the seedlings are a pale yellow colour
Yellow Seedlings
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Expose these yellow seedlings to light for 2 days – Seeds go
green
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This demonstrates that light was needed for the development of
chlorophyll
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