Mating animals to produce certain characteristics

Low Birthweight Heavier Weaning Weight Color Horned or Polled Temperment

Animals are the result of Feed, Health, and Inheritance (genetic material)

Feed is fastest to correct Genetics last longest

All body cells contain “Blueprints” with instructions as to how an animal will look or act etc.

One Gene comes from each parent (pairs) Genes are divided into sections

(Chromosomes) that carry genes Sex chromosomes: male = XY, female = XX

Dominant Genes = one gene overshadows the other

Angus Cattle: black is dominant, red is not (Bb)

Hereford: white face is dominant (Ww) Hampshire Hog: white belt is dominant Horns are dominant (Pp)

The gene that is overshadowed by a dominant gene

Recessive genes can only express themselves if both genes are recessive

Polled vs Horned (Pp) (pp) Black wool vs white (Ww) (ww) Dwarfism vs normal size (dd) Albino

P = horned p = polled If a homozygous horned cow (PP) is mated to

a homozygous polled bull (pp), what percent of the calves will be horned, polled?

P P

p

p

Pp Pp

Pp Pp

If a homozygous horned cow (PP) is mated to a heterozygous horned bull (Pp), what percent of the calves will be polled?

P P

p

p

Pp Pp

Pp Pp

Some recessive genes are attached to the X and Y chromosomes

Humans: Colorblindness and Baldness are on the X chromosomes

In Men, traits expressed anytime present In Women, must have two recessives to

show trait Children get baldness from mothers

X Y

X XX XY

XX XYX

X Y

X XX X Y

XX XYX

B

B

B

X Y

X XX X Y

XX XYX

BB B

X Y

X XX X Y

XX XYX

BB B

B B B

If both genes express themselves Shorthorn Cattle: Red male mated to a White

female = Roan calf RR + WW = RW

Shorthorn Cattle R = Red W = white RW = roan If a red bull (RR) is mated to a white cow

(WW), what color will the calves be?

R R

W

W

RW RW

RW RW

If a red bull (RR) is mated to a roan (RW) cow, what color will the calves be?

R R

R

W

RR RR

RW RW

R W

R

W

RR RW

RW WW

Dwarfism Monorchid = only one testicle descends Cryptorchid = no testicles descend Short ears & tails

Dramatically different from what is expected genetically

Horned calf from polled parents Loss of some or extra body parts Lethal Mutation: causes death at birth Sublethal Mutation: limits animals ability to

grow to maturity Beneficial Mutation: loss of tail in lambs

Similar to a Mutation, only it is caused by something in the environment

Siamese twins

Chance that traits will be inherited Low: multiple births, fat covering Medium: birth wt, wean wt, milk, wool grade,

carcass wt, rate of gain High: Loin eye area, fleece length & quality

Currently have ewes that wean 70 lb lambs Want to raise weaning wt to 110 lbs Select a ram with a wean wt of 110 lbs Heritability of weaning wt is 30% What can you expect new lamb crop to weigh

at weaning?

What is the difference in current weaning wt and that of the new ram?110 - 70 = 40 lbs

Heritability % x difference30% x 40 = 12 lbs

Can expect a gain in weaning wt of 12 lbs 70 lbs + 12 lbs = 82 lbs

Random Mating: all males have an equal opportunity to mate with all females

Outcrossing: mating purebreds with unrelated purebreds

Inbreeding: mating related animals Linebreeding: parents mated to offspring

Crossbreeding: mating animals of same species but different breeds

Offspring will outperform either of the parents

Corn Breed A yields 100 bu/acre Corn Breed B yields 100 bu/acre Crossbreed A & B yields corn that yields

200 bu/acre Vigor only expressed in crossbreeding Donkey mated to a horse = Mule

mule is sterile

Animals not common to United States Difficult to define today New breeds are exotics

Genotype: genetic makeup (Bb) Phenotype: physical appearance (Black) Heterosis: Genes are different, Dominant &

Recessive (Bb) Homozygous: both genes are the same (BB

or bb)