Beef Selection

Question 1

Beef Infrastructure

Answer 1

Purebred
Cow/calf
Stocker
Feedlot
Packer
Consumer

Question 2

Differences from Dairy

Answer 2

1) Producer goals and objectives
2) Different environment and lever of available natural resources
3) More traits of economic importance
4) Sources of available performance records
5) Slower adaptation to technology

Question 3

More traits of economic importance

Answer 3

Slower progress
Lack of vertical integration
Genetic correlation of traits

Question 4

Sources of available performance records

Answer 4

Unlike dairy, no centralized record keeping system

Each AI organization has own sire formats based on information from each breed association

Question 5

Problems

Answer 5

Performance records - sire summaries doesn’t mean semen or bull is still available
Genotype and environment can dramatically alter performance of individuals

Question 6

Crossbreeding

Answer 6

High level used
Beef cows 45% 2 breed cross
Beef calves 47% 3 or more breed crosses

Question 7

Across breed EPD adjustments

Answer 7

Most useful to commercial producers purchasing bulls for use in crossbreeding programs
Emphasis - uniformity for rotational crossbreeding
[Accuracy of across-breed EPS depends on accuracy of within-breed EPD for the bull]

Question 8

Deleterious Recessive Alleles

Answer 8

Heavily selected against
If possible, genetic testing is used to select against

Question 9

Curly Calf Syndrome

Answer 9

Autosomal recessive
Phenotype - Curved spine, extended and contracted limbs, tends to appear thin

Question 10

Developmental Duplication [DD] (polymelia)

Answer 10

Calves born with extra limbs (can be caused by embryo environment)
Complication - incomplete penetrance (animals that are dd don’t exhibit duplication)

Question 11

Genetic testing

Answer 11

Used for different traits
* Homozygous vs heterozygous polled
*Homozygous vs heterozygous black
* Tenderness markers (calpastation - want homozygous)

[Thyroglobulin - trait for marbling]

Question 12

Good points

Answer 12

1) Many economic traits have high h2 and are not sex-limited
2) Many traits can be easily measured
3) Consolidation of packing industry

Question 13

Keys to success - Genetic standpoint

Answer 13

1) Recognition of value of performance records and EBV’s
2) Recognition and identification of breeds that excel in certain characteristics
3) Selection
4) Adjusted weaning weights
5) MPPA (Most probable producing ability)

Question 14

Repeatability

Answer 14

Estimates probability of repeating documented performance in future

Always higher than h2 because accounts for maternal influence of cow that can be documented by previous calf performance

h2 + maternal influence = R

Question 15

Recognition of value of performance records and EBV’s

Answer 15

Learn what they mean and how they are determined

Question 16

Selection

Answer 16

Avoid fads/short term outlook
Select breeds compatible with objectives and environment

Question 17

Adjust weaning weights

Answer 17

Purpose is to account for variations in weight between animals weaned at one time
Possible sources of variation w/in herd - genetic, age of calf, breed, age of dam, sex of calf (sex dimorphism)

Eliminates some sources of variation