Genetics in the Cattle Industry

ANSC 309

genetics

study of heredity or the way traits are passed from the parents to offspring

chromosomes

functional units of inheritance; located in the nucleus and occur in pairs; contain genes

genes

small segment of a chromosome that contains codes for specific traits

gametes

male and female reproductive cells

spermatogenesis

formation of sperm

oogenesis

formation of ova (eggs)

meiosis

cell division of sex cells so that offspring receives 1 chromosome from each parent

mitosis

cell division that results in 2 identical daughter cells; how the body grows

cells contain a ________

nucleus

nucleus contains _________

chromosomes

chromosomes contain _____

DNA

specific segment of DNA is a ________

gene

fertilization

union of egg and sperm forms chromosome pairs

zygote

result of fertilization

allele

variant of a gene for a trait

heterozygous

different traits

homozygous

same trait

know homozygous vs heterozygous and dominant vs recessive

…

why is genetic studies in livestock important?

• increases productivity

• produces disease resistant breeds

• produce adaptable traits that maximize growth and weight gain

• eliminating unfavorable traits

what are the 2 types of breeding in livestock?

• straight breeding

• cross breeding

examples of straight breeding

• pure breeding

• inbreeding

• outcrossing

• grading up

examples of cross breeding 

• 2-breed crosses

  • Brangus

  • white faces angus

• 3-breed crosses

  • beefmaster

• rotation breeding

describe a purebred

animal has the characteristic of the breed to which it belongs

both parents must be purebred

tend to be genetically homozygous

what breed is often used as breeding stock?

purebred

purebred animals are eligible for registry unless it possess undesirable qualities? what are some of these qualities they look at?

a certain color/markings

describe an inbred animal

mating of closely related animals

both desirable and undesirable traits become more visible

inbred animals are mostly used in what setting?

research settings

why is inbreeding expensive?

requires culling of undersirable traits

describe close breeding

the animal being mater can be traced back to more than 1 common ancestor

sire to daughter, son to dam, brother to sister

has higher risk of negative traits

what is the most intensive form of inbreeding?

close breeding

describe outcrossing

mating of animals of different families within the same breed

undesirable traits are hidden

tend to be heterozygous 

what is the purpose of outcrossing?

to bring in desirable traits that were not present in the original animals

straight breeding is often used in _____ ________ operations

pure breeding

describe grading up breeding

mating purebred sires to grade females

very common method on most farms

improves the quality of the offspring

why are grading up breeds not eligible for registry?

because only the sire is purebred

in what breeding type is selection of the bull important?

grading up breeding

describe cross breeding

mating of 2 animals from different breeds

what can cross breeding maximize? what can it eliminate?

can maximize desirable traits in certain breeds of animals

can eliminate certain health issues

rotational breeding

rotates sires from 2 different breeds

what are some examples of cross breeds?

angus/brahman

kiko/boer goats

horse/donkey

hybrid vigor

the superiority of the crossbred offspring over the average of the pure breeds (paren

what are the 2 primary reasons to crossbreed?

heterosis and complementarity of traits

heterosis

the performance of crossbred offspring exceeds the performance of the purebred parents

hybrid vigor

superior traits that result from crossbreeding

can increase productivity by as much as 25% in beef cattle

genetic engineering

process of identifying and transferring a gene/(s) for a specific trait from 1 organism to another

steps in genetic engineering

• identify the gene that controls the desired trait

• locate the gene of the DNA strand

• the DNA is cut in a specific area to isolate the gene

• the cut strand of DNA is placed in a vector (virus or plasmid of bacteria)

• vector is placed in the organism to produce the desired trait

clones

cell or organisms that are genetically identical to each other

achieved in a lab

use somatic cell nuclear transfer

benefits of cloning

• testing disease treatments on identical animals isolates the true effectiveness of the treatments

• organ transplants

• pharmaceutical production

• duplicating genetically superior animals

• cloning endangered species to increase numbers

embryo transfer

flushing embryos from the reproductive tract of desirable cows and implanting them in other cows that may be of lower quality

a cow can produce many embryos through ______________

superovulation