Animal Breeding

selection differential

difference between mean of selected parents and the population from which

they came

tandem selection

alternating selection among traits across generations

independent culling levels

culling based on a minimum level of performance for each trait

Selection for extremes

selection of animals with high performance in any one trait

genetic lag

the time it takes for any genetic improvement made in the selection program of

the top tier of the pyramid to trickle down to commerical level

inbreeding depression

negative effect of inbreeding on vigor when management controls for

environmental effects

inbreeding

the mating of animals that are related

linebreeding

the mating of animals that are related in order to propagate the genes of one

particular animal

crossbreeding

the mating of animals of two or more different breeds

outcrossing

the mating of unrelated animals within a breed. although crossbreeding is

more extreme than outcrossing, the genetic effects of both are similar

heterosis

increased performance of the offspring over the average performance of the

parents when unrelated individuals are mated.

two-breed cross

purbred animals of two different breeds are used for crossing to create F1

two-breed rotation

crossbred F1 females are kept for breeding and are mated to nonrealted males

from one of the parent breeds

Three breed rotation

males from each of the three breeds are used in succession on crossbred

females

three-breed terminal cross

F1 females are produced from two purebred lines, then bred to a different

breed of sire to produce market offspring

Increases

as selection intensity increases, response to selection______

Companion animals ; Commercial Herds

predicting individual offspring is typical for _______but it is not used for ________because group performance is more important

Decrease

when selecting for multiple traits, the value of the selection for each individual trait will _______ for each trait, compared to the effect of selecting for a single trait

Inbreeding

many breeds were developed as a function of______

Less

traits with high heritability have ________ heterosis than traits with low heritability

increases

outbreeding and crossbreeding ________heterozygosity

decreases

heterozygosity _________ after the F1 generation

maternal

reciprocal crosses must be evaluated for performance because of _______ influences

less

as animals mature, heterosis has _______ of an effect because of environmental influences

1/3 ; 2/3

two-breed rotations eventually stabilize at ______Breed A and _______Breed B or the inverse

1/7 ; 2/7 ; 4/7

three-breeed rotations eventually stabilize at proportions of _________,________, and ________ of each of the breeds.

wool

what is the "Jacob" sheep used for

wool

what is the "merino" sheep used for

meat

what is the "suffolk" sheep used for

hair/mohair

what is the "angora" goat used for

meat

what is the "boer" goat used for

milk

what is the "nubian" goat used for