HomeBreeding and Selection Breeding: the mating and production of offspring by animals. The activity of controlling the mating and production of offspring of animals Selection: the act of choosing something or someone from a group Geneus species of livestock European cattle- Bos taurus Zebu Cattle- Bos Indicus Swine- Sus Scrofa Sheep- Ovis Aries Horse- Equus Cabellus Goat- Capra Hircus Dog- Canis Familaris Cat- felis catus Principles of Breeding and Genetics Phenotype: the characteristic of an animal that can be seen or measured Genotype: the genetic makeup of an individual (DNA) Phenotype= Genotype + Environment Genotype= phenotype - Envoromet Selection: differently producing what one wants in a herd. Allowing only certain mating to occur. Inheritance: transmission of genes from parents to offsprings Basic Cell Information Chromosomes: in the nucleus and contains genetic material Gene: an active area in the chromosome that codes for trait DNA: complex molecule of the chromosomes which is the coding mechanism of inheritance Gametogenesis: Process that the gonads produce cells that become gametes(ova and sperm) Spermatogenesis: production of sperm Oogenesis: production of egg or ova Meiosis- special type of nuclear division in which germ cells contain one member of each chromosomes pair Fertilization: when an egg and sperm unite from embryo Each contributes one chromosome per pair to new life Homosygous: an individual whose genes for a particular trait are identical or alike Heterozygous: individual who possesses unlike genes for particular trait Dominant: a gene that overpowers and prevents the expression of its recessive allele when the two alleles are present in a heterozygous individual Recessive: a gene that its expression is masked by dominant allele Allele: gene occupying corresponding loci on homologus chromosomes that affect the same trait What traits should one select? Only traits that contribute to productive efficiency and consumer acceptance are of economic importance Ex: reproduction, growth(pre-weaning, post weaning) Basis of Selection Appearance Genetic abnormalities Estimate carcas merit Fit standard for herd Reproduction record Individuals records Progeny testing Pedigree family Factors affecting genetic progress Selection differential Heritability Genetic interval Accuracy of records Genetic correlation Number of traits in selection program Things to remember about traits Heritability: amount of the phenotypic expression of a trait that is transmitted to offspring (enviroments have big effect) (h2) Heterosis: the tendency of a crossbred individual to show qualities superior to those of both parents Generation interval The average age of the parents when offsprings are born The shorter the generation interval, the faster the genetic interval Selection Methods Tandem Selection: Selection for one trait at a time Least effective: mattes rapid gain in a single trait, but is slow to reach selection goal involving several traits Independant culling: establishes minimum culling levels for each trait makes SLOWER gain for each trait, but reaches goals faster. Most effective when few traits are involved. Selection Index: each animal is rated numerically by combining performance of several traits into a single index New Mexico Ram Test Selection Index Index=12 + 40 (ADG) + 30(CWF) + SL - 12 (DIA) - o.5 (VAR) All variables expressed as ratio of individual to the average ADG= average daily grain CWF= clean wool fibers SL= staple length DIA= Fiber diameter VAR= difference between dide and Britch Breeding Systems Purebred breeder: develop breeding stock that pocessess the highest predictability for transmitting the most desirable inheritance possible purebred animal: meets the requiramnets of a recognized breed and whose ancestors are registered in the herd book of that breed Breed: race or variety of livestock where the members are related by descent and are similar Purebred breeders may use: Linecrossing: crossing different lines or unrelated animals of the same breed, it is also used as outcrossing for outbreeding systems. It results in an increased heterozygosity and heterosis (offspring will not breed true). Heterosis: increase in production in the offspring over average of parents. Inbreeding: mating of related individuals( sires and dams share at least one ancestor) results in a increase of homozygosisty Inbreeding coefficient: measures of how inbred an animal is( the probability two genes of a pair in an individual will be homozygous because they are replicates of a single ancestor gene Coefficient ranges from 0-1. 0=no change, 1=absolute certenity Increase inbreeding usually detrimental to: reproductive performance, pre-weaning growth, post-weaning growth, increase susceptibility to environmental stress Commercial Producers: make use of available genetic material in a manner to maximize production or give most efficient, rapid and economical prodyction possible Systems used by commercial producers Species crossing- how many result in nonfertile offsprings Crossbreeding- mating animals of different established breeds and takes advantage of complementary and heterosis(hybrid vigor) oucrossing/ linerarcrossing- mating of unrelated animals of same breed Grading up- making purebred sires to commercial grade females and their female offspring for several generations Most common species crosses Jack to mare= mule Stallion to jennet= hinny Zebu to european cattle= brangus cattle American bison to cattle= buffalo Cross breeding system- designed to maximize hybrid vigor(heterosis) and produce replacement females throught the rotation of different sire breeds Terminal Static crossbreding system Produces replacement females throught the rotation while taking advantage of producing crossbred offspring Also know as “terminal crossbreeding system” Replacament females can be purchased from or produced in separate population Composiste breeding system Combines desirable traits of two or more breeds of cattle into one package Composition must be carefully planed in order to achieve genetic merit Utilizes hybrid vigor without crossbreeding Systems of mating Determied by: type of facilities, breeding schedule, method of heat detection, genetic program, market target hand/Stud mating Purebred breeders use to control breeding Females are kept apart from the males until desire time of breeding, Horse, Rabbit and Poultry advantages prevents overse of particule sire certainity of mating and to which Sire can increase conception rate by 5-10%. Disadvantages increases labor estrus detection becomes a seven-day a week job Pen mating Males and females coexist throught the breeding seasons or year rounds Used mostly by commercial breeders advantages Minimum labor Heat detection is the responsibility of the sire disadvantages Uncertainty of mating and date of conception Uncertainty of infertile sires and of un-bred females May overwork sires Artificial Insemination referred as AI Process by which semen from male is placed into the reproduction tract of the female using mechanical means rather than by natural source advantages Decrease spreed fo disease Increase number of offspring from superior male Identifies the fertility of sire Reduces number of sires needed Allows mating of small females to larger males Genetic diversity disadvantages Requires trained level of management Increases time and supervision of the female herd for estrus detection Sire training Semen handling and special breeding facilities More costly Embryo transfer Removal of early pregnancy embryos from a genetically superior female and placement of these embryos into reproduction tract of a suitable recipient for gestation and parturition Reproduction defined: process by which animals produce offsrpings for the purpose of continuing the species. The process of reproduction begins with copulation, which is the mating of a male and female of the species Sperm cells from the male are deposited in the female reproduction tract and try to unite with an egg cell When fertilization( a sperm cell and an egg cell units) occurs, an embryo begins The embryo attaches to the wall of the uterus where it is protected, recieves nourishment, and develops When the new offspring reaches the end of the gestation period, it is delivered from the female reproductive tract in a process called parturition

Breeding and Selection Breeding: the mating and production of offspring by animals. The activity of controlling the mating and production of offspring of animals Selection: the act of choosing something or someone from a group Geneus species of livestock European cattle- Bos taurus Zebu Cattle- Bos Indicus Swine- Sus Scrofa Sheep- Ovis Aries Horse- Equus Cabellus Goat- Capra Hircus Dog- Canis Familaris Cat- felis catus Principles of Breeding and Genetics Phenotype: the characteristic of an animal that can be seen or measured Genotype: the genetic makeup of an individual (DNA) Phenotype= Genotype + Environment Genotype= phenotype - Envoromet Selection: differently producing what one wants in a herd. Allowing only certain mating to occur. Inheritance: transmission of genes from parents to offsprings Basic Cell Information Chromosomes: in the nucleus and contains genetic material Gene: an active area in the chromosome that codes for trait DNA: complex molecule of the chromosomes which is the coding mechanism of inheritance Gametogenesis: Process that the gonads produce cells that become gametes(ova and sperm) Spermatogenesis: production of sperm Oogenesis: production of egg or ova Meiosis- special type of nuclear division in which germ cells contain one member of each chromosomes pair Fertilization: when an egg and sperm unite from embryo Each contributes one chromosome per pair to new life Homosygous: an individual whose genes for a particular trait are identical or alike Heterozygous: individual who possesses unlike genes for particular trait Dominant: a gene that overpowers and prevents the expression of its recessive allele when the two alleles are present in a heterozygous individual Recessive: a gene that its expression is masked by dominant allele Allele: gene occupying corresponding loci on homologus chromosomes that affect the same trait What traits should one select? Only traits that contribute to productive efficiency and consumer acceptance are of economic importance Ex: reproduction, growth(pre-weaning, post weaning) Basis of Selection Appearance Genetic abnormalities Estimate carcas merit Fit standard for herd Reproduction record Individuals records Progeny testing Pedigree family Factors affecting genetic progress Selection differential Heritability Genetic interval Accuracy of records Genetic correlation Number of traits in selection program Things to remember about traits Heritability: amount of the phenotypic expression of a trait that is transmitted to offspring (enviroments have big effect) (h2) Heterosis: the tendency of a crossbred individual to show qualities superior to those of both parents Generation interval The average age of the parents when offsprings are born The shorter the generation interval, the faster the genetic interval Selection Methods Tandem Selection: Selection for one trait at a time Least effective: mattes rapid gain in a single trait, but is slow to reach selection goal involving several traits Independant culling: establishes minimum culling levels for each trait makes SLOWER gain for each trait, but reaches goals faster. Most effective when few traits are involved. Selection Index: each animal is rated numerically by combining performance of several traits into a single index New Mexico Ram Test Selection Index Index=12 + 40 (ADG) + 30(CWF) + SL - 12 (DIA) - o.5 (VAR) All variables expressed as ratio of individual to the average ADG= average daily grain CWF= clean wool fibers SL= staple length DIA= Fiber diameter VAR= difference between dide and Britch Breeding Systems Purebred breeder: develop breeding stock that pocessess the highest predictability for transmitting the most desirable inheritance possible purebred animal: meets the requiramnets of a recognized breed and whose ancestors are registered in the herd book of that breed Breed: race or variety of livestock where the members are related by descent and are similar Purebred breeders may use: Linecrossing: crossing different lines or unrelated animals of the same breed, it is also used as outcrossing for outbreeding systems. It results in an increased heterozygosity and heterosis (offspring will not breed true). Heterosis: increase in production in the offspring over average of parents. Inbreeding: mating of related individuals( sires and dams share at least one ancestor) results in a increase of homozygosisty Inbreeding coefficient: measures of how inbred an animal is( the probability two genes of a pair in an individual will be homozygous because they are replicates of a single ancestor gene Coefficient ranges from 0-1. 0=no change, 1=absolute certenity Increase inbreeding usually detrimental to: reproductive performance, pre-weaning growth, post-weaning growth, increase susceptibility to environmental stress Commercial Producers: make use of available genetic material in a manner to maximize production or give most efficient, rapid and economical prodyction possible Systems used by commercial producers Species crossing- how many result in nonfertile offsprings Crossbreeding- mating animals of different established breeds and takes advantage of complementary and heterosis(hybrid vigor) oucrossing/ linerarcrossing- mating of unrelated animals of same breed Grading up- making purebred sires to commercial grade females and their female offspring for several generations Most common species crosses Jack to mare= mule Stallion to jennet= hinny Zebu to european cattle= brangus cattle American bison to cattle= buffalo Cross breeding system- designed to maximize hybrid vigor(heterosis) and produce replacement females throught the rotation of different sire breeds Terminal Static crossbreding system Produces replacement females throught the rotation while taking advantage of producing crossbred offspring Also know as “terminal crossbreeding system” Replacament females can be purchased from or produced in separate population Composiste breeding system Combines desirable traits of two or more breeds of cattle into one package Composition must be carefully planed in order to achieve genetic merit Utilizes hybrid vigor without crossbreeding Systems of mating Determied by: type of facilities, breeding schedule, method of heat detection, genetic program, market target hand/Stud mating Purebred breeders use to control breeding Females are kept apart from the males until desire time of breeding, Horse, Rabbit and Poultry advantages prevents overse of particule sire certainity of mating and to which Sire can increase conception rate by 5-10%. Disadvantages increases labor estrus detection becomes a seven-day a week job Pen mating Males and females coexist throught the breeding seasons or year rounds Used mostly by commercial breeders advantages Minimum labor Heat detection is the responsibility of the sire disadvantages Uncertainty of mating and date of conception Uncertainty of infertile sires and of un-bred females May overwork sires Artificial Insemination referred as AI Process by which semen from male is placed into the reproduction tract of the female using mechanical means rather than by natural source advantages Decrease spreed fo disease Increase number of offspring from superior male Identifies the fertility of sire Reduces number of sires needed Allows mating of small females to larger males Genetic diversity disadvantages Requires trained level of management Increases time and supervision of the female herd for estrus detection Sire training Semen handling and special breeding facilities More costly Embryo transfer Removal of early pregnancy embryos from a genetically superior female and placement of these embryos into reproduction tract of a suitable recipient for gestation and parturition Reproduction defined: process by which animals produce offsrpings for the purpose of continuing the species. The process of reproduction begins with copulation, which is the mating of a male and female of the species Sperm cells from the male are deposited in the female reproduction tract and try to unite with an egg cell When fertilization( a sperm cell and an egg cell units) occurs, an embryo begins The embryo attaches to the wall of the uterus where it is protected, recieves nourishment, and develops When the new offspring reaches the end of the gestation period, it is delivered from the female reproductive tract in a process called parturition

Breeding and Selection

Breeding: the mating and production of offspring by animals. The activity of controlling the mating and production of offspring of animals
Selection: the act of choosing something or someone from a group

Geneus species of livestock

European cattle- Bos taurus
Zebu Cattle- Bos Indicus
Swine- Sus Scrofa
Sheep- Ovis Aries
Horse- Equus Cabellus
Goat- Capra Hircus
Dog- Canis Familaris
Cat- felis catus

Principles of Breeding and Genetics

Phenotype: the characteristic of an animal that can be seen or measured
Genotype: the genetic makeup of an individual (DNA)
Phenotype= Genotype + Environment
Genotype= phenotype - Envoromet
Selection: differently producing what one wants in a herd. Allowing only certain mating to occur.
Inheritance: transmission of genes from parents to offsprings

Basic Cell Information

Chromosomes: in the nucleus and contains genetic material
Gene: an active area in the chromosome that codes for trait
DNA: complex molecule of the chromosomes which is the coding mechanism of inheritance

Gametogenesis: Process that the gonads produce cells that become gametes(ova and sperm)

Spermatogenesis: production of sperm
Oogenesis: production of egg or ova

Meiosis- special type of nuclear division in which germ cells contain one member of each chromosomes pair

Fertilization: when an egg and sperm unite from embryo

Each contributes one chromosome per pair to new life

Homosygous: an individual whose genes for a particular trait are identical or alike

Heterozygous: individual who possesses unlike genes for particular trait

Dominant: a gene that overpowers and prevents the expression of its recessive allele when the two alleles are present in a heterozygous individual

Recessive: a gene that its expression is masked by dominant allele

Allele: gene occupying corresponding loci on homologus chromosomes that affect the same trait

What traits should one select?

Only traits that contribute to productive efficiency and consumer acceptance are of economic importance
Ex: reproduction, growth(pre-weaning, post weaning)

Basis of Selection

Appearance

Genetic abnormalities
Estimate carcas merit
Fit standard for herd

Reproduction record

Individuals records
Progeny testing
Pedigree

family

Factors affecting genetic progress

Selection differential
Heritability
Genetic interval
Accuracy of records
Genetic correlation
Number of traits in selection program

Things to remember about traits

Heritability: amount of the phenotypic expression of a trait that is transmitted to offspring (enviroments have big effect) (h2)
Heterosis: the tendency of a crossbred individual to show qualities superior to those of both parents

Generation interval

The average age of the parents when offsprings are born
The shorter the generation interval, the faster the genetic interval

Selection Methods

Tandem Selection: Selection for one trait at a time

Least effective: mattes rapid gain in a single trait, but is slow to reach selection goal involving several traits

Independant culling: establishes minimum culling levels for each trait

makes SLOWER gain for each trait, but reaches goals faster. Most effective when few traits are involved.

Selection Index: each animal is rated numerically by combining performance of several traits into a single index

New Mexico Ram Test Selection Index

Index=12 + 40 (ADG) + 30(CWF) + SL - 12 (DIA) - o.5 (VAR)

All variables expressed as ratio of individual to the average
ADG= average daily grain
CWF= clean wool fibers
SL= staple length
DIA= Fiber diameter
VAR= difference between dide and Britch

Breeding Systems

Purebred breeder: develop breeding stock that pocessess the highest predictability for transmitting the most desirable inheritance possible

purebred animal: meets the requiramnets of a recognized breed and whose ancestors are registered in the herd book of that breed
Breed: race or variety of livestock where the members are related by descent and are similar
Purebred breeders may use:

Linecrossing: crossing different lines or unrelated animals of the same breed, it is also used as outcrossing for outbreeding systems.

It results in an increased heterozygosity and heterosis (offspring will not breed true).
Heterosis: increase in production in the offspring over average of parents.

Inbreeding: mating of related individuals( sires and dams share at least one ancestor) results in a increase of homozygosisty

Inbreeding coefficient: measures of how inbred an animal is( the probability two genes of a pair in an individual will be homozygous because they are replicates of a single ancestor gene
Coefficient ranges from 0-1. 0=no change, 1=absolute certenity
Increase inbreeding usually detrimental to: reproductive performance, pre-weaning growth, post-weaning growth, increase susceptibility to environmental stress

Commercial Producers: make use of available genetic material in a manner to maximize production or give most efficient, rapid and economical prodyction possible

Systems used by commercial producers

Species crossing- how many result in nonfertile offsprings
Crossbreeding- mating animals of different established breeds and takes advantage of complementary and heterosis(hybrid vigor)
oucrossing/ linerarcrossing- mating of unrelated animals of same breed
Grading up- making purebred sires to commercial grade females and their female offspring for several generations

Most common species crosses

Jack to mare= mule
Stallion to jennet= hinny
Zebu to european cattle= brangus cattle
American bison to cattle= buffalo

Cross breeding system- designed to maximize hybrid vigor(heterosis) and produce replacement females throught the rotation of different sire breeds

Terminal Static crossbreding system

Produces replacement females throught the rotation while taking advantage of producing crossbred offspring
Also know as “terminal crossbreeding system”
Replacament females can be purchased from or produced in separate population

Composiste breeding system

Combines desirable traits of two or more breeds of cattle into one package
Composition must be carefully planed in order to achieve genetic merit
Utilizes hybrid vigor without crossbreeding

Systems of mating

Determied by: type of facilities, breeding schedule, method of heat detection, genetic program, market target

hand/Stud mating

Purebred breeders use to control breeding
Females are kept apart from the males until desire time of breeding, Horse, Rabbit and Poultry
advantages

prevents overse of particule sire
certainity of mating and to which Sire
can increase conception rate by 5-10%.

Disadvantages

increases labor
estrus detection becomes a seven-day a week job

Pen mating

Males and females coexist throught the breeding seasons or year rounds
Used mostly by commercial breeders
advantages

Minimum labor
Heat detection is the responsibility of the sire

disadvantages

Uncertainty of mating and date of conception
Uncertainty of infertile sires and of un-bred females
May overwork sires

Artificial Insemination

referred as AI
Process by which semen from male is placed into the reproduction tract of the female using mechanical means rather than by natural source
advantages

Decrease spreed fo disease
Increase number of offspring from superior male
Identifies the fertility of sire
Reduces number of sires needed
Allows mating of small females to larger males
Genetic diversity

disadvantages

Requires trained level of management
Increases time and supervision of the female herd for estrus detection
Sire training
Semen handling and special breeding facilities
More costly

Embryo transfer

Removal of early pregnancy embryos from a genetically superior female and placement of these embryos into reproduction tract of a suitable recipient for gestation and parturition

Reproduction defined: process by which animals produce offsrpings for the purpose of continuing the species.

The process of reproduction begins with copulation, which is the mating of a male and female of the species
Sperm cells from the male are deposited in the female reproduction tract and try to unite with an egg cell
When fertilization( a sperm cell and an egg cell units) occurs, an embryo begins
The embryo attaches to the wall of the uterus where it is protected, recieves nourishment, and develops
When the new offspring reaches the end of the gestation period, it is delivered from the female reproductive tract in a process called parturition.

Male anatomy

Male anatomy function:

gamete(sperm)

Production
Storage
deposition

Produces male sex hormones
Is a passageway for expelling urine

Disadvantage: kidney stones(because sperm and urine come out of the same place; if males tract is blocked, sperm can't come out, can't reproduce

Scrotum

Is a two lobed sac
Is homologus the labia majora in the female
Contains two layers

Thick skin which contains large sweat and sebaceous glands
Smooth muscles which cause it to shrink or expand in relation to temperature

Protects and supports testes
Temperature takes a big factor in sperm( if too hot or too cold, sperm dies)
Cremaster muscle, spermatic cord and tunica dartos muscle

Lie within the wall of the scrotum
Raise or lower the testies to maintain constant testicular temp(temperature takes a big factor in sperm- if too hot or too cold, sperm dies) temperature should be 4 to 6 degrees below body temperature for normal sperm development

Testes

Are paired, oval shaped organs
Functions:

Produce sperm- Temperature takes a big factor in sperm( if too hot or too cold, sperm dies)
Produce testosterone (male sex hormones)

Testosterone causes development of secondary sex characteristics and sex behavior

Have seminiferous tubules

Coil through testes
Site of sperm production and maturation

Is housed in the scrotum
Is covered with tunica vaginals
Has an outer connective tissue layer referred to as the tunica albuginea

Epididymis

Is a coiled tube, attached to each testicle
Is responsible for further maturation, storage and transportation of sperm cells
Because location of testes vary among livestock species, location of the epididymis varies
Paired structure
Functions:

Sperm concentration
Storage of sperm
Transport of spermatozoa

Sperm is mature and motile by the time the sperm leaves
Divided into 3 parts

captus(head) epididymis: closest to the testes
Corpus (body) epididymis
Cauda (tail) epididymis: contains very concentrated sperm

Consists of a single conulated tube

Sermatic Cord

Is a paired structure
Functions include:

Carries nerves and blood supplys to testes
Carry sperm to urethra
Controls temperature

Contains internal and external cremaster muscle which control the proximity of the body

Vas Deferance (Ductus Deferens)

Transports sperm from the epididymis to the urethra
Carries urine from bladder
Carries sperm and fluid from accessory sex organ

Urethra

Single structure
Transports sperm and urine
Is also part of the genito-urinary system
Structure includes:

Pelvic urethra: part of pelvic area
Penile Urethra: part of tube inside penis

Accessory Glands

Provides 95-98% of total ejaculate
Ejaculate its sperm plus the added accessory fluids
Includes:

Seminal vesicles(vesicular glands): secrete fluids providing energy and buffers to sperm
Prostate gland: secretes a thick, milky fluid high in inorganic ions
Bulbourethral glands( cowper’s glands): secrete fluids before ejaculation to clean urethra

Penis

Passageway for semen and urine
Deposits semen in female reproductive tract
Fibroelastic Penis
- Bulls, rams, boars
- Primarily composed of connective tissue and little on blood
Vascular penis
- Stallions
- Supplied with blood vessels

Sigmoid Flexure

Has an s-shaped curve
Allows for penis retraction
Stallions and humans do not have sigmoid flexure

Restructure Penis muscle

Extends penis upon sexual excitement

Sheath

protects penis from injury and infection

Spermatogenesis

Process by which sperm is formed
Occurs in the seminiferous tubules
Begins at puberty
Is a continuous process throughout the life of a male

Sperm anatomy

doesn’t grow or divide
Contains head and tail

Sperm morphology- wrong sperms

Poultry Anatomy

Differences include:
- testes are located within the abdominal cavity and produce sperm and seminal fluid
- papillae emit semen and are considered the copulatory organs or the rooster
- cloaca serves as the passageway for urinary, digestive and reproductive tracts
- androgen is the male sex hormone produced by the testes

Age of puberty

Cattle: 11(7-18)months

• Sheep: 7(6-9)months

• Swine: 7(5-8)months

• Horse: 14(10-24)months

• Goat: 3 to 7 months

• Dog: 9(5-12) months

• Cat: 9(8-10) months

• Human: 9 to 16 years