Beef selection

what is the beef infrastructure

purebred, cow/calf, stocker, feedlot, packer, consumer

what are the major differences from dairy

1. producer goals and objectives 2. different environment/level of natural resources 3. more traits of economic importance 4. sources of available performance records 5. slower adaptation to technology

what are the traits of economic importance

slower progress, lack of vertical integration, genetic correlation of traits

what are the differences from DHIA

no centralized record keeping - each major breed association has own published sire summary with their own formats

what are the problems with performance records

sire summaries don't mean semen or bull is available, BVs calculated within breed only, genotype x environment interaction can alter performance

why is there a slower adaptation to technology

small herds and part time ranchers, only 13% of operations use some AI

what are the levels of crossbreeding for beef cows

45% 2 breed cross 35% 3+ breed cross

what are the levels of crossbreeding for beef calves

37% 2 breed cross 47% 3+ breed cross

what are across creed epd adjustments

useful to commercial producers purchasing bulls for use in crossbreeding

what do EPD adjustments emphasize

uniformity for rational crossbreeding, divergence for terminal crossbreeding, divergence of birth weight EPDS to first calf heifers

why does accuracy for across breed epd depend on

accuracy of within breed EPD for bull

what else is genetic testing used for

homo vs. hetero polled

homo vs. hetero black

tenderness markers

What are the 3 good points of beef selection?

1. many economic traits have high h2 and are not sex limited 2. many traits are easily measured 3. consolidation of packing industry

what are the keys to success from a genetic standpoint

1. recognition of value of performance records and EBVs 2. recognition and identification of breeds that excel in certain characteristics 3. selection 4. adjusted weaning weights 5. MPPA

what are adjusted weaning weights

to account for variations in weight between animals weaned at 1 time

what are possible sources of variation within a herd

genetic, age of calf, breed, age of dam, sex of calf

what is MPPA

most probably producing ability - account for cows with differ4ent number of records and repeatability

what is repeatability

Estimates probability of repeating documented performance in the future - expression of same trait at different times in the same individual

what is the heritability and repeatability of weaning weight?

h2 = .3, r = .4

what is r higher than h2

accounts for maternal influence of cow that can be documented by previous calf performance