Transcript 3. Crossbreeding Systems

Crossbreeding Systems
You shall keep my statues. You shall not let your
cattle breed with a different kind;…
Leviticus 19:19
Breeding
Scheme
Design
• Crossbreeding
– One of the few “Free” things in beef production
• A crossbred cow returns
about $90/year more than a
straight-bred cow.
• A crossbred calf returns about
$70/head more than a
straight-bred calf.
Evaluating
Crossbreeding
Systems
•
Use seven criteria:
1.
2.
3.
4.
5.
6.
7.
Merit of component breeds
Hybrid vigor
Breed complementarity
Consistency of performance
Replacement considerations
Simplicity
Accuracy of genetic prediction
Merit of
Component
Breeds
• Each breed must bring
favorable attributes to the
mix
– Would not choose Longhorn if having polled,
heavy muscled cattle was important
Hybrid Vigor
• The most important reason
for crossbreeding
• Find a system that
maximizes hybrid vigor
Breed
Complementarity
• Big Bull x Small Cow theory
– Sire x Dam Complementarity
• Choose a maternal breed
type for females
Consistency of
Performance
• Produce as consistent of calf
crop as possible
• Some systems do a better
job at this
Replacement
Considerations
• The ultimate female is an F1
• How does the system
produce females?
– Can it produce F1 females?
Simplicity
• KISS principle should apply
• It is very easy to
overcomplicate production
Accuracy of
Genetic
Prediction
• Higher the accuracy of
prediction, the lower the
selection risk
– More predictable offspring
• EPD’s are a great tool to
increase Accuracy of Selection
Types
• Rotation
– Space
– Time
• Terminal
– Static
– Rota-terminal
Spatial
Rotation
Rotation in
Time
Simple
Terminal
Complex
Terminal
Rota-terminal
Heterosis
System
Attributes
System
HV
Comp
Consistency
Replacements
Ease
Accuracy
Two Breed
Spatial
+
-
Varies
+
+
+
Rotation in
Time
+
+
Varies
+
++
-
Static
Terminal
++
++
+
-
++
+
RotaTerminal
+
+
Varies
+
-
+
Questions