Animal Reproduction Objective 8.01: Understand animal reproduction and parturition

Terminology Castration –Removing the testicles of the male to prevent breeding Colostrum –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

Terminology Estrus Cycle –The length of a females cycle from one estrus to the next Puberty –Age at which animals reach sexual maturity and begin to come into heat

Terminology Ovulation –The release of the egg from the ovary Fertilization –The union of the sperm and the egg cells

Fertilization

The Female Reproductive System

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

The ovaries have three major functions: Gamete production Secrete estrogen (hormone) absence of muscle development 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 days.

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

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)

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 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 SpeciesAct Offspring Cowscalvingcalf Eweslambinglamb Sowsfarrowingpig Henshatchingchick Maresfoalingfoal Goatskiddingkid

Reproductive Functions (Female) Gestation and Lactation Periods: SpeciesGestation PeriodLactation(Milking) Cow283 daysbeef days dairy days Ewe148 days days Sow114 days days Mare days days

Reproductive Functions (Female) Estrous period length by species: Cow hours Ewe hours Sow hours Mare hours Hens & Womennone

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 21 days Ewe22 days Sow21 days Mare22 days Hennone

The 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

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: Papilla Testicles Cloaca Vent Ovary Magnum Isthmus Uterus Vagina Use page 190 in your textbook

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.

Parturition of Animals

Parturition Normal Position –Front feet first –Nose tucked between front legs –Shoulders –Body –Hips –Back legs Any other presentation can cause serious problems for the animal

Parturition Process –Increased Estrogen causes contractions –First water bag emerges and breaks –Second water bag emerges and breaks (contains fetus) Several hours later, the placenta and other membranes (afterbirth) are expelled

Animal Genetics Objective 8.02: Understand genetics of animal breeding

Animal Cell The body is made up of millions of tiny cells Most of the cell is made up of protoplasm

Cell Parts –Protoplasm- The material or contents inside of a cell. –Cell Membrane- Thin layer of protein and fat that surround the cell. Some substances can pass into the cell and the membrane blocks others materials from entering.

Cell Parts –Nucleus- Gives cell ability to grow, digest food and divide. Contains chromosomes and DNA. –Cytoplasm- Jellylike substance that gives the cell shape and contains components necessary for cell functions.

Cell Parts –Lyosome- Round shaped organelles that contain digestive enzymes that allow for digestion of cell nutrients. –Mitochondrion- Rod-shaped organelles that convert the energy stored in glucose into ATP (adenosine triphosphate).

Cell Parts –Nucleolus- Organelle found inside the nucleus. Produced ribosomal RNA. –Endoplasmic Reticulum- Transports materials through the cell.

Cell Parts –Nuclear membrane- Membrane that surround the nucleus. –Golgi body- Located near the nucleus and produces the membrane that surrounds the lyosomes.

Cell Parts –Centrosome- Small body where the microtubules are made. The centrosome divides during mitosis. –Vacuole- Fluid filled membrane that fills with food and waste products inside the cell. –Ribosome- Site of protein synthesis.

Cell Division Mitosis –Increases total number of cells –Results in animal growth –Chromosomes pairs are duplicated

Cell Division –Prophase- the nucleolus disappears and centrioles move to opposite ends of the cell. Fibers begin to form and extend from the centromeres. –Metaphase- spindle fibers align the chromosomes along the middle of the cell nucleus.

Cell Division –Anaphase- the paired chromosomes separate and move to opposite sides of the cell. –Telophase- nuclear membrane forms around the newly divided chromosomes and cell membrane begins to contract.

Cell Division Meiosis –Produces gametes –Only have one-half the chromosomes of normal cells

Cell Division Gamete Formation –One set of chromosomes come from the sperm and one from the ovum. –The zygote that is created during fertilization has chromosomes from each parent. Chromosomes match up with one another based on the genetic information they carry.

Cell Division Production of sperm is called spermatogenesis. –Male animals begin producing sperm at sexual maturity. –Spermatocytes divide into spermatids through meiosis.

Cell Division Production of an ovum is called oogenesis. –Females also begin producing ova at sexual maturity. –The oocytes divide and form an ovum. The ovum contains cytoplasm and stored food. It provides nourishment for the zygote and embryo.

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 39 –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

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

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

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

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

Answer A Punnett Square for two animals that are heterozygous for two traits: Polled=P Black= B (Alternatives are horned and red) PBPbpBpb PB PPBBPPBbPpBBPpBb Pb PPBbPPbbPpBbPpbb pB PpBBPpBbppBBppBb pb PpBbPpbbppBbppbb Dam Sire 9:3:3:1

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 weight40% Weaning Weight25-30% Yearling Weight60% Fertility10% Tenderness60%

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