Animal Science Exam 3

What is the process of making proteins?

- DNA cannot leave the nucleus so a molecule RNA or ribonucleic acid is made of genetic code. - messenger RNA transports the instructions from the DNA to the ribosomes outside the nucleus which is where the proteins are produced

What are the differences and similarities between embryo transfer and in vitro fertilization?

- ET: donor has to stay "open" and some cows dont respond to hormones as expecteed - in vitro: allows for eggs to be directly collected from the ovary, collection of ova during pregnancy, use of different sires on the ova from each collection, frequent collections, but the tech is not perfected and its expensive

What is an EPD? Define it in relation to breeding value.

- Expected progeny difference - a prediction of the difference between the performance of an individual's progeny compared to all contemporaries for the progeny - half of the breeding value is equal to the EPD

What is PSS? Why should individuals with this condition be culled?

- Porcine stress syndrome: genetic defect in which pigs are heavily muscled but have poor carcass quality and may die when subjected to stress - can die from this condition under stress

Chromosomes occur in pairs in somatic cells and contain...

- a diploid (2n) number of chromosomes

What are alleles?

- a gene can have various forms which are alleles - for each gene there are two alleles (one for each parent) - alleles affect the same trait, but each allele cause the production of a different protein and thus differences in the way the trait is expressed

What is a contemporary group?

- a group in which animals of a given sex and age, having similar treatment, are given an equal opportunity to perform

Germ (gametes) cells contain only...

- a haploid (n) number of chromosomes - haploid cells passed on by parents combine to produce new cell with full genetic complement of DNA

Define heritability.

- a measure of the amount of phenotypic variation that is due to additive gene effects. The proportion of differences between individuals that is genetic.

Define heritability. What is the range for heritability values?

- a measure of the proportion of the phenotypic variation that is due to additive gene effects - range of values is from 0 to 1 and can thought of as percentages or proportions

Define and explain the value of accuracy and possible change.

- accuracy: the measure of reliability associated with an EPD. If little or no info is available, accuracies may range as low was 0.01. A high accuracy would 0.99. determine how extenisivley to use a bull - possible change: the measure of potential error associated with EPD values. - as accuracy increase, possible change decrease

what is principle of segregation?

- alleles separate so that only one (randomly chosen) is found in any particular gamete

How does the short generation interval in the pig give swine breeders an advantage in making genetic progress?

- allow rapid genetic progress for economically important traits

Describe the value of DHI in dairy cattle breeding programs.

- allows for constant genetic improvement

What is the value of embryo transfer?

- allows for the production of many more offspring from genetically superior females

- what does homozygous mean?

- an animal that has matching alleles at a given point on the chromosome, or locus (specific location of a gene on a chromosome)

What is animal breeding and the goal?

- animal breeding : applied genetics - science to aid in goal of breeding "better" animals

What is a maternal effect in beef cattle? What are its components?

- any environmental influence that the dam contributes to the phenotype of her offspring - mothering ability, milk production environment, maternal instinct

What are recessive alleles?

- are expressed only when there is no dominant allele present - represented by lowercase letters

Speculate the value of across-bred EPDs. What are the problems in calculating these values?

- better for commercial bull buyers using more than one breed of bull - additional information is required because EPDs are typically only used with in a breed basis

What is biotechnology? Genetic engineering? How are they related?

- biotechnology: a set of powerful tools that employ living organisms (or parts) to make or modify products, improve plants or animals or develop microorganisms for specific uses. - genetic engineering: advances made in recombinant DNA technolgy; form of biotechnology

For what traits can EPDs be calculated?

- birth, weaning, and yearling weights, fat thickness, milk,

Why is understanding genetic correlations important in beef cattle breeding? Describe such a relationship between two traits.

- can improve overall performance - feed efficiency and rate of grain have a relationship

What is a chromosome?

- contains large molecules of DNA. composed of segments called genes

how do genetics overlap with both the consumer and producer?

- cost, related to efficiency to production

What are some of the signs that various species display during estrus?

- cow is standing to be mounted and allows others to mount her - mares winking of the vulva following urination - sows will stand still when pressure is applied to their back

Describe the importance of capitalizing on heterosis in sheep breeding.

- crosses tend to be more vigorous, fertile, healthier and grow faster - improve economic efficiency

What is DNA?

- deoxyribonucleic acid - a complex molecule composed of nucleotides joined together with phosphate sugars - (RNA is a single strand of DNA)

What are the challenges to successful AI?

- detection of estrus - placement of semen in the reproductive tract

Who is Gregor Mendel?

- discovered principles of inheritance while working with garden peas in 1866 - basis for how traits are inherited

how are genetics important to a producer?

- efficiency of production is often top priority

What is weaning weight EPD?

- evaluates genetic merit for growth

What is milk EPD?

- evaluates genetic merit for mothering ability

What is a genotype?

- genetic makeup of an organism - determines: disposition, coat type, coat color, speed, gait types, body composition, growth, reproduction, milk production, disease resistance, etc.

In what situation might it be advantageous to calculate estimated EPDs from pedigree info? What would you expect the accuracy of such EPDs to be?

- good for young bulls that have not had their performance info included yet - not that accurate

What is the value of artificial insemination to a breeding program?

- improve genetic reproduction and genetics of farm animals - Single most important physiologic technology ever devised for accelerating genetic improvement

What is the principle of independent assortment?

- in formation of gametes, separation of a pair of genes is independent of separation of other pairs

Why is animal breeding more important as a discipline now than it was 50 years ago?

- increased understanding of the nature of genetic variation - increased application of the tools of the animal breeder to herds and flocks - advent of sufficient computing power to deal with complex math problems to identify superior individuals

Where is genetic material located?

- inside the cell, in the nucleus--> chromosome--> DNA

What does it mean for EPDs within a breed to be standardized? What is a base year?

- it means a zero EPD represents the avg. genetic merit of animals in the database - a particular year or historic base EPD the breed association picks

What does NSIF and NPPC contribute to swine breeding excellence?

- key organizations for documentation on swine genetic resources. - provide guidelines for measuring and recording swine performance data

What is the caution that producers must exercise in order to protect the long-term integrity of the genetic pool of livestock if they use technology to enhance reproduction.

- maintaining reproduction function - must work to increase the genetic potential for high reproductive function

what is epistasis?

- many gene pairs work together to produce gene expression - expression of one gene is influenced by the presence of another - coat color in many species is affected by epistasis

What is combined maternal EPD?

- maternal weaning weight - reflects both the milking ability transmitted to daughters and the direct weaning growth transmitted through daughters to their calves

What is the value of estrus synchronization?

- minimize the labor involved - combat the problem of estrous detection

What are four methods by which gene frequencies are changed in a population?

- mutation: changes in the chemical composition of a gene - genetic drift: a change in gene frequency of a small breeding population owing to chance - migration: the process of bringing new breeding stock into a population - selection: the process of allowing some animals to reproduce more than others

what is a trait?

- observable characteristic; who you are.

What is a phenotype?

- observable characteristics, result from interaction of genotype and environment - change throughout life - shape, size, color - inherited genotype not always expressed in phenotype - recessive genes not always expressed in phenotype but could later show up in offspring

explain inheritance?

- occurs by transmission of genes from parent to offspring at time of conception - method by which alleles are passed from 1 generation to the next - molecular material is passed on/combined to form the characteristics that will describe both the physical and molecular composition of the resulting individual

What does heterozygous mean?

- one with differing alleles (Aa)

example of how animal breeding has been taken to the extreme to reach the ideal carcass

- pictures of angus steers show the difference, steers were super short and fat, then chianinas were brought in and created super tall and lean carcasses, now they are balanced

What kind of gene action takes place in qualitative vs. quantitative traits?

- qualitative: those traits for which phenotypes such as coat color can be classified into groupes - quantitative: those traits that are numerically measured and are usually controlled by many genes, each having a small effect, such as milk or egg production

What are the gametes?

- reproductive cells - each parent produces gametes and within each gamete is a single allele for a gene - in the formation of gametes, parental alleles separate so each gamete contains only half of the genetic code the parent possesses

What are the areas of emphasis in swine breeding? How does visual appraisal contribute?

- reproductive complex, growth rate and efficiency, and carcass traits - visual appraisal is important, feet and leg soundness along with underline soundness may be scored bc they affect production and reproduction success

What are major areas of economic importance in beef cattle breeding?

- reproductive efficiency, mature size, calf growth, maternal performance, and carcass traits

Describe the difference in heritablitlty among growth traits, reproductive traits, and carcass traits in beef cattle.

- reproductive traits have lower heritablity - growth traits tend to have moderate - carcass traits tend to have fairly high

Describe the difference in the use of EPDs in the selection of seedstock herd compared to selection in a commercial herd.

- seedstock has to use them and also provides them for commercial herds - commercial herds have to consider environment

Why was more emphasis placed on the breeds of sheep than other animals?

- selection of breeds utilized in a commercial operation is crucial to the success and profitability of the operation

What is incomplete dominance?

- situation in which no dominance exists and heterozygous individual appears as an intermediate between the two alleles - example: red anngs and charolais cross = yellow color

What is a gene?

- small sections of DNA that code for a specific purpose. direct the synthesis of proteins or perform regulatory functions.

What is a genome?

- sum of genetic material of an animal

Describe the procedure for E.T. in cattle.

- super-ovulation of a female - synchronization of recipients to donor - embryos stay in donor cow for about 7 days and then flushed out of the uterus - the embryos are then identified under a microscope and then planted in recipients

how do genetics matter to the consumer?

- tenderness, flavor, leaness often top priority

what is meiosis?

- the development of germ cells (gametogenesis) - reduction from 2n to n

What is codominace?

- the exception to the rule of dominance that occurs when neither allele masks the other and both are expressed in the phenotype - ex: roan shorthorn

Why is expression important?

- the expression of genotype into traits of economic importance provides basis for animal's worth

Define digestion

- the physical, chemical, and enzymatic means the body uses to render a feedstuff ready for absorption

what is mitosis?

- the process of somatic cell division - replication

What does it mean if an allele is dominant?

- they are alleles that are expressed over recessive alleles - expressed as capital letters

What is genetics?

- thought of as foundation for life - provides the ability to transfer information across generations necessary for life

What is a somatic cell scores (SCS)? Does avaible info suggest that the SCS is influenced much by genetics?

- tool that allows producers to select bulls based on their ability to sure daughters with lower rates of mastitis. - research suggests that genetic change to reduce mastitis is slow because the influence is different across breeds.

- what does each normal body tissue cell, or somatic cell (includes all cells but gametes) have?

- two sex chromosomes (XX: female; XY: male) - a n autosomes, which are all chromosomes other than sex chromosomes

Can E.T. be used on all the common species of livestock?

- yes but is mainly used on cattle

possible problems of test crossing

-Dominance of genes makes it difficult to determine if an animal is heterozygous or homozygous for the dominant trait -"TH" Tibial Hemimelia - Characterized by large abdominal hernia & twisted back legs, sometimes skull deformity (Shorthorn & Maine Anjou) - "PHA" Pulmonary Hypoplasia with Anasarca- Born dead with underdeveloped lungs and extreme edema in the interstitial space (Shorthorn, belted Galloway, dexter breeds)

when did Spallanzani, successfully inseminated female dog

1780

How many chromosomes do pigs have?

38

How many chromosomes do sheep have?

54

How many chromosomes do cattle have?

60

How many chromosomes do goats have?

60

How many chromosomes do chickens have?

78

Have all animals benefited from animal breeding research?

No, has not been as extensive in horses, goats and companion species

Compare/contrast dominant and recessive alleles?

SIMILAR: alleles that pass down traits to thee offspring. DIFFERENT: dominant alleles mask recessive ones; dominant alleles are expressed with a capital letter

Why would it be convenient to be able to look at animal and determine genotype based on its phenotype?

Would make for more efficient selection process

Define the term gene?

a short segment of a chromosome. genes direct the synthesis of proteins or perform regulatory functions

What animals within a breed can have EPDs calculated?

any animals

E.T. is most commonly used on what species? Why:

cattle because it is easiest and most cost effective

How long will semen last if properly processed, frozen and stored?

frozen semen can be stored indefinitely

What is the term that refers to the entire genetic composition of an individual??

genome

A trait that is lowly/highly (choose one) heritable for a given trait allows more genetic change for that trait from one generation to the next.

higher b/c the higher the heritability estimates can be selected and more obvious

What is the difference between an animal that is homozygous for a gene and one that is heterozygous?

homozygous- when two genes of a pair are the same heterozygous- when two genes in a pair are not the same

How is semen collected for use in artificial insemination?

is usually collected by using an artificial vagina or an electroejaculator

What is an allele?

one of two or more alternative forms of a gene occupying corresponding sites (loci) on homologous chromosomes.

What is the physical appearance of an animal known as?

phenotype

When the sex of an individual determines how a gene is expressed as in the phenotype, this is known as a _________ trait.

sex influenced trait

Milk production is an example of what kind of trait?

sex limited trait

Each gamete contains autosomes and _____________ sex chromosomes.

somatic

What is the process that takes place within the nucleus of a cell whereby a copy of a DNA molecule is formed from another?

the cellular process of making a copy of a DNA molecule

What does the term gene frequency describe?

the proportion of loci in a population that contain a particular allele

Define population genetics

the study of how gene and genotypic frequencies change, and thus change genetic merit in a population

Define animal breeding.

the use of biometry and genetics to improve farm animal production