Animal Reproduction and Genetics Terminology Objective Define terminology

Animal Reproduction and Genetics

Terminology • Objective: – Define terminology related to reproductive management and breeding systems including castration, colustrum, estrus, gestation, lactation and parturition.

Terminology • Castration – Removing the testicles of the male to prevent breeding • Colustrum – First milk • Gestation – Time an animal is pregnant

Terminology • Estrus – When a female is receptive to be bred • Lactation – Period of time that milk is secreted by the mammary glands • Parturition – Than act of giving birth

Breeding Systems • Objective – Discuss crossbreeding, grading-up, inbreeding, linebreeding, and purebreeding

Breeding Systems • Pure Breeding – Registered male and female animals – Angus X Angus

Breeding Systems • Cross Breeding – Mating a male and female of different breeds – Angus X Charolais = Crossbreed

Breeding Systems • Inbreeding – Mating closely related animals – Brother X Sister – Son X Mother – Father X Daughter

Breeding Systems • Linebreeding – Breeding more distant relatives than inbreeding – Cousin X Cousin

Breeding Systems • Grading-Up – Mating purebred male (sires) to unregistered or corssbred females (dams) – Yorkshire bore X Yorkshire/Hampshire sow – Hybrid Vigor • Superior traits from crossbreeding • Offspring are better than parents

The Female Reproductive System Objective: Identify the parts of the female reproductive system of livestock

Female Tract

Female Reproductive System • Ovary - the ovary is comparable to the male testicle and is the site of gamete production. – A bovine animal has 20, 000 potential eggs per ovary, while a human female has 400, 000 potential eggs per ovary. – Ova are fully developed at puberty and are not continuously produced as in the male. – All species contain two functional ovaries except for the hen which has only a left functioning ovary.

Female Reproductive System

Female Reproductive System The ovaries have three major functions: • • Gamete production Secrete estrogen (hormone) • • • absence of muscle development of mammary glands development of reproductive systems and external genitalia fat deposition on hips and stomach (source of energy) triggering of heat Form the corpus luteum

Female Reproductive System • Infundibulum - the funnel shaped portion of the fallopian tube near the ovary that catches the ovulated egg. • Fallopian Tubes (or Oviducts) - pair of small tubes leading from the ovaries to the horns of the uterus (5 - 6 inches). – Fertilization occurs in the oviduct. – Egg travels from ovary to uterine horn in 3 - 4 days.

Female Reproductive System

Female Reproductive System • Uterine Horn - The anterior, divided end of the uterus in the cow, ewe, and mare. Sow has only 2 horns, no body, woman has no horns, only body.

Female Reproductive System

Female Reproductive System Uterus - Muscular sac connecting fallopian tubes and cervix 1. Sustains the sperm and aids in its transport 2. Supports embryo and fetus during gestation 3. Expels fetus at parturition

Female Reproductive System • Cervix – Area between the uterus and vagina – Normally closed – Opens at estrus and parturition – (2 -3 inches)

Female Reproductive System • Vagina - the female organ of copulation 1. admits penis 2. receives semen (except in sow) 3. passageway for fetus at parturition • Bladder - storage organ for urine • Vulva - extended genitalia; opening for both urinary and genital tracts

Female Reproductive System

Reproductive Functions (Female) Steps in the female reproductive process: 1. Ovulation — Produce gamete (ova or ovum) — Release of egg(s) — Infundibulum pushes the ovum into the fallopian tube

Reproductive Functions (Female)

Reproductive Functions (Female) 2. Estrus (heat, estrous period) – Period of time when a female will accept a male in copulation – The female must stand (standing heat) to be mounted before the reproductive process can begin

Reproductive Functions (Female) 3. Gestation — Fertilization to parturition — Develop embryo in uterus 4. Parturition — Expel fully developed young at birth 5. Lactation — Milk production

Reproductive Functions (Female)

Ovulation Rates by Species Cow 1 egg per estrus Ewe 1 to 3 eggs per estrus Sow 10 to 20 eggs per estrus Mare 1 egg per estrus Hen. Approx. 28 eggs per month

Reproductive Terminology Species Cows Ewes Sows Hens Mares Goats Act calving lambing farrowing hatching foaling kidding Offspring calf lamb pig chick foal kid

Reproductive Functions (Female) Gestation and Lactation Periods: Species Cow Gestation Period 275 - 285 days Ewe Sow Mare Woman 115 112 330 270 - 142 days - 115 days - 345 days Lactation(Milking) beef 180 - 270 days dairy 305 - 365 days 60 - 90 - 120 days 21 - 42 days 90 - 150 days ? years

Reproductive Functions (Female) Estrous period length by species: Cow 12 - 18 hours Ewe 24 - 36 hours Sow 48 - 72 hours Mare 90 - 170 hours Hens & Women none

Reproductive Functions of the Female Estrous cycle - time from one heat period (or menstrual cycle) to the next. Length of estrous cycle by species: Cow 19 - 21 days Ewe 16 - 17 days Sow 19 - 21 days Mare 21 - 24 days Woman 28 days Hen none

The Male Reproductive Tract Objective: Identify the parts of the male reproductive system of livestock and poultry

Male Reproductive Tract

Male Reproductive Tract • Scrotum - external sac that holds testicles outside of the body to keep sperm at 4 -5 o. F cooler than the body temperature • Testicles - the primary male organs of reproduction • • to produce sperm to secrete testosterone

Male Reproductive Tract • Epididymis - Long coiled tube that is a path for sperm – – Provide passageway for sperm out of the seminiferous tubules Storage for sperm Fluid secretion to nourish sperm Place for sperm maturation

Male Reproductive Tract • Vas Deferens - slender tube from epididymis to urethra which moves sperm to the urethra at ejaculation • Urethra - long tube from bladder to penis; passageway for urine and sperm out of the body

Male Reproductive Tract • Penis - male organ of copulation which conveys semen and urine out of the body • Penis retractor muscle - allows extension and retraction of the penis; sigmoid flexure extends in copulation

Male Reproductive Tract Accessory Glands: • Seminal vesicles- add fructose and citric acid to nourish the sperm • Prostate Gland - located at the neck of the bladder – cleans the urethra prior to and during ejaculation – provides minerals for sperm – provides the medium for sperm transport – provides the characteristic odor of semen

Male Reproductive Tract • Cowper’s gland • Also called the Bulbourethral gland • Paired organs • cleans the urethra prior to semen passage

Male Reproductive Tract

Reproduction in Poultry Objective: Specify how the reproductive system for poultry functions

Reproduction in Poultry The poultry oviduct has five parts: 1) Vagina – Holds the egg until laid 2) Uterus – Secretes the shell 3) Isthmus – Adds the two shell membranes 4) Magnum – Secretes the albumen 5) Infundibulum – Where fertilization takes place

Reproduction in Poultry • Major difference: – Embryo of livestock develop inside the female’s body while the embryo of poultry develops inside the egg. • Poultry only have the left ovary and oviduct when mature • The yoke is the ovum • Chicken Incubation – 21 days

Poultry Reproduction In your notes, define the following poultry reproductive terms and tell how they differ from livestock we have studied so far: Use page 190 in your textbook • Papilla • Testicles • Cloaca • Vent • Ovary • Magnum • Isthmus • Uterus • Vagina

Assignment: Build a crossword puzzle containing 12 reproductive terms from your class notes. Have another student complete and sign your crossword puzzle. The assignment as well as your other assignment from the handout is due at the end of class.

Animal Reproduction and Genetics Objective: Describe the cell and process involved in cell division including how genes affect the transmission of characteristics

Animal Cell • The body is made up of millions of tiny cells • Most of the cell is made up of protoplasm • Cell parts: § Nucleus § Cytoplasm § Cell wall

Animal Cell Nucleus Cytoplasm Cell Wall

Cell Division • Mitosis – Increases total number of cells – Results in animal growth – Chromosomes pairs are duplicated • Meiosis – Produces gametes – Only have one-half the chromosomes of normal cells

Fertilization • When the sperm from a male reaches the egg from a female • Two cells join to form a complete cell • Pairs of chromosomes are formed again • Many different combinations of traits are formed

Fertilization

Chromosomes • Rod shaped bodies • Made of protein • Found in the cell nucleus • Exist in pairs except for gamete cells • The number of chromosome pairs differ for various animals – Cattle 30 – Swine 19 – Horses 33 – Chickens 6 – Humans 23

Genes • Located on chromosomes • Thousands found in each animal • Control inherited characteristics – Carcass traits – Growth rate – Feed efficiency • Two types of inherited traits § Dominant § Recessive

Assignment 1. Read pages 186 2. Complete problems 1 -9 3. Write the question and provide a short answer in complete sentences.

Genes • Dominant gene – Hides the effect of another gene – Polled condition in cattle is dominant – The gene is represented by a capital letter • Recessive – Gene that is hidden by another – The gene is represented by a lower case letter

Genes Example: The dominant gene is written- P The recessive gene is written-p P= Polled p= horned

Homozygous and Heterozygous • Homozygous gene pair – Carries two genes for a trait – Polled cow might carry the gene PP • Heterozygous – Carries two different genes that affect a trait – Polled cows might carry a recessive gene with the dominant Pp

Predicting Genotype • Genotype-kind of gene pairs possessed • Phenotype- the physical appearance of an animal • Punnett squares are used to predict genotypes and phenotypes of animals

Punnett Square Polled Dam Polled Sire P= Polled p= horned Example: • Two polled cattle that are homozygous for the polled trait P PP PP PP

Punnett Square Normal Dam Sire Carrier N= Normal size n= Dwarfism Example: • Normal size in cattle is dominant to dwarfism N NN NN n Nn Nn

Punnett Square Normal Dam Sire Carrier N= Normal size n= Dwarfism Example: • What if both parents are carriers for a trait or disorder? N n N NN Nn nn Result: one out of every four births could result in a dwarf animal (1: 2: 1)

Assignment (Alternatives are horned and red) Dam Sire Complete a Punnett Square for two animals that are heterozygous for two traits: • Polled=P • Black= B

Answer Sire A Punnett Square Dam for two animals PB Pb p. B pb that are heterozygous for PB PPBb Pp. BB Pp. Bb two traits: Pb PPBb PPbb Pp. Bb Ppbb • Polled=P p. B Pp. Bb pp. BB pp. Bb • Black= B pb Pp. Bb Ppbb pp. Bb ppbb (Alternatives are horned and red) 9: 3: 3: 1

Heritability • Objective: – Discuss hertability estimates for beef and swine

Heritability • Estimated the likelihood of a trait being passes on from the parent to the offspring – Low heritability • slow herd improvement – High heritability • faster improvement

Heritability • Swine rates are usually lower than cattle • Heritiability for carcass traits are higher than reproductive traits • Estimates vary from 0 to 70%

Birth weight 40% Weaning Weight 25 -30% Yearling Weight 60% Fertility 10% Tenderness 60%

Heritability Review • Herd improvement – slow for low heritability – faster for high heritability • Estimates are higher for: – beef compared to swine – carcass traits compared to repro