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267 Cards in this Set
- Front
- Back
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Aristotles 2 Theories -what did he think formed embryos? |
-Preformation: the embryo was pre-formed and grew or enlarged during development -Epigenesis: man arose from the successive differentiation of a formless being He thought the embryo was organized from the moms menstrual blood after being acted upon by seman |
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Fillopius |
in 1562 the Italian anatomist/ botanist first described the oviduct (fallopian tubes) |
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Coiter |
in 1573 he discovered/ described the Corpus Luteum |
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De Graff |
in 1672 discovered the ovarian follicle |
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Hamm + Leeuwenhoek |
in 1677 discovered sperm with the first microscope -in 1825 it was discovered that the sperm fertilize oversights |
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Driesh |
in 1900 he demonstrated that cells isolated from fertilized ovum were capable of developing into an embryo |
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Artificial Insemination |
1907 studies conducted on farm animals, dogs, foxes, rabbits and poultry -first published text in 1933 -soon after used it to study infertile animals |
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In vitro |
first procedure in rabbits in 1959 but almost 20 years would elapse before success in humans |
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the female reproductive system consists of |
-2 ovaries -mullerian ducts (ovaducts, uterus, cervix, vagina) -exterior vagina and vuvla |
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what is the major function of the female reproductive system |
-produce a female gamete -deliver it to the site of fertilization via male gamete -provide environment for growth of embryo/fetus -deliver the fetus |
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3 Purposes of Reproduction |
1. Perpetuate the species (natures 2nd strongest impulse) 2. Provision of food (surplus of animals for food and initiation of lactation) 3. Genetic Improvement (only when offspring are produced can impact of genetic improvement be realized) |
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Success of reproduction relies on the interaction between |
the endocrine system and reproductive anatomy |
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why is reproduction the most economically important trait? |
it determines the number of salable and maintained animals and their products |
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what are the ovaries |
the primary reproductive organs in females -very dynamic (left/right) |
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what are Oocytes? |
female gametes that are produced by the ovaries -ovaries also produce female sex hormones (estrogen/ progesterone) also known as steriodgenesius -highly vascularized which ensures continual nutrient and oxygen delivery -serve an endocrine function and the vascular network of the ovaries ensures delivery of hormones to and from this organ to target tissue |
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corpus lutetium |
also known as yellow body -dosent form until after ovulation and forms from the same cell as the follicle -produces progesterone (relaxes the uterus to help maintain early pregnancy) -can only live long enough for an embryo to be recognized and if not it'll die |
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Primary Follicles |
are established by meiosis 1 with in fetus -haploid -exist as a group -every female is born with a certain number of follicles which act as the supportive environment of the ova) |
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atresia |
death of follicles that begin at birth and continue forever |
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secondary follicles |
can occur during puberty/ after -larger in size |
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Mature/ Tertiary follicles |
-"Graafian" -fully formed follicle capable of ovulation/ fertilization -takes a year to go from primary to mature |
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does estrogen contract or relax the uterus |
contracts |
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ovaducts |
-fallopian tubes -pair of convoluted tubes that are adjacent to the ovaries and extending to the uterus -site of fertilization and early cell divisions of the embryo -transport ova and sperm towards each other -muscular tissue with contractile properties that is generally divided into three sections |
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infundibulum |
-adjacent to the ovaries, -lace-like structure that envelopes the ovaries and is responsible for capturing the released oocyte and directing its transport |
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in the sow, ewe, and cow the infundibulum... |
remains separate from the ovary |
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in the rat, mouse and hamster the infundibulum... |
forms a bursa that surrounds the ovary |
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in the mare the infundibulum... |
is attached to the ovary |
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ampulla |
highly unvaccinated which increase the SA and are covered with many cilia to aid in the movement of the oocyte down the ampulla |
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Ampullary-Isthmic Junction |
-site of fertilization which delays transport of oocytes for several hours to increase chances of fertilization |
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Isthmus |
-final section of the oviduct -once fertilized the zygote undergoes mitotic divisions as it travels 3-6 days through the isthmus towards the uterus -decreased SA and cilia push ovacyte embryo towards the utero-tubual junction |
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utero-tubual junction |
oviductal contractions move sperm in both directions with in oviduct so only a portion of the sperm advances toward ovary -connect to uterus |
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basic anatomy of the uterus |
-consists of 2 uterine horns, a uterine body and is composed of 3 layers 1.Perometrium 2. Myometrium 3. Endometrium |
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Perometrium |
outer covering of the uterus |
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Myometrium |
middle, smooth muscle later that is responsible for uterine contractions |
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Endometrium |
mucosal lining of the uterus -site of embryonic implantation/ attachment (extra embryonic membranes) depending on species for the formation of the placenta --takes 6-20 days for implantation (invasive/strong) or attachment (non-invasive/ weak) |
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Duplex Uterus |
marsupials/ rabbits -very distinct uterine horns and not much uterine body -2 cervix and one vagina -marsupials have 3 vaginas (two external, one birthing canal) |
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Bicorruate Uterus |
-poorly to moderatley developed uterine horns -2 horns, one body -Cow, Mare and Sow |
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simplex |
no uterine horns, just the uterine body -primates |
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discord placenta |
-Primates -implantation with erosion of maternal tissue associated with the placenta -strong attachment via implantation -exchange of waste, antibodies, and nutrients but no exchange of blood (abort) |
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Zoanary Placenta |
-dogs, cats and elephants -extra embryonic attachment with a pool of nutrients that are pulled from -band around the middle called the Zone of Exchange that takes part in fetal/ maternal exchanges of antibodies (not nutrients/wast) |
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Placentron placenta |
-ruminants -button like structure that attach (extra embryonic attachment) to the uterus (80-100) and they are greatest around where the fetus is developing --caruncles (maternal side of button) --cotyledons (fetal side of button) -no antibody exchange (immunological nieve) |
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Diffuse Placenta |
-sows and mares -has connections all over the placental surface -extra embryonic attachment |
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What is the cervix? |
a thick walled, cartilaginous, elongated, smooth muscle sphincter that remains tightly closed except during estrous and parturition that protects the uterine environment -located between uterus and vagina -flexible |
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cervix in the cow and ewe |
transverse, interlocking ridges that are usually referred to as annular rings -cow have short cervix -ewe have long cervix with interlocking rings that don't line up |
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Functions of the cervix |
1. Passage way for fetus and sperm -filters nonviable sperm and consistently releasing viable sperm into the uterus to fertilize ova 2. Barrier to prevent bacteria from reaching uterus -does this via annular rings and the antibacterial properties of cervical mucus that forms a mucosal plug during pregnancy |
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function of male reproductive anatomy |
to produce and deliver gametes to the female reproductive system |
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what is necessary for sperm to survive? |
the proper environment |
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what does the male reproduction system consist of? |
-testes -wolffian system (epididymis, vas deferens, urethra, accessory glands, penis and prepuce) |
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testes differentiation |
-SRY gene: testes determining factor -female system is the default system that forms in the absence of testes -produce an anti-mullerian hormone which inhibits the female system from forming and turns on the wolffian ducts very early on in development |
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testes defintion and function |
-Definition: primary organ of reproduction in males --oval shaped lobes separated by connective tissues -Function: to produce male gametes (spermatozoa) and male reproductive hormones (testosterone/ androgens) |
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what do the testes start producing sperm? |
puberty |
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Seminiferous Tubules |
small convoluted tubules located with in lobes of testes -90% total mass of testes -contain germ cells and are the site of sperm production -Contains leydig and nurse/steroli cells |
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Leydig Cells |
are located in-between the seminiferous tubules and function to produce testosterone and other androgens when stimulated by Leutinizaing Hormone |
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Steroli/ Nurse Cells |
located with in tubules that surround developing sperm and nourish them and mediate effects of follicle stimulating hormone and testosterone on germ cells |
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Scrotum |
two-lobed sac that conforms to the shape and size of the testes -divided in 2 compartments by the scrotal septum |
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Spermatic Cord |
composed of blood vessels, nerves, muscle fibers, connective tissues and a portion of the vas deferens -along with the scrotum it physically supports the testes and also work together to regulate temperature |
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Epididymis |
long, convoluted tube that functions to store and concentrate and transport sperm -maturation of sperm occurs as it passes through gaining motility and fertility via the removal of cytoplasm and mitochondria (takes 10-15 days) |
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what makes the perfect environment for sperm? |
low pH and high CO2 concentration |
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how is the sperm concentrated? |
occurs in epithelial cells lining the epididymis which absorb some fluid |
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Transport of Semen through the Epididymis is affected by |
1. Pressure from production of more sperm 2. External pressure created by normal movement and exercise 3. Negative pressure caused by ejaculation (positive movement) -due to peristaltic contractions of the vas deferens and urethra |
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why do we only have maternal mitochondria? |
because it leaves the cells with the cytoplasm during the maturation process in the epididymis |
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Vas Deferens |
transport ducts for sperm which follow along the spermatic cord -passes through the inguinal canal to the pelvic region where they join the urethra near the opening of the bladder -transport is facilitated by smooth muscle contractions in the walls of the vas deferens |
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Urethra |
a singe excretory duct extending from the opening of the urinary bladder to the end of the penis -expels urine and semen |
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Spermatocytes to Spermatids |
-developing sperm cells progressing through meiosis (phase I and II) |
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Accessory Sex Glands |
located along pelvic portion of the urethra and produce the majority of the ejaculate/ semen which acts as a medium for the transport of semen -adds buffers, nutrients and inorganic ions required to assure optimal motility and fertility of sperm |
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what does semen do to protect sperm? |
aiding in the neutralization of the acidic environment present in female GI tract |
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Ampullae |
enlargements of the vas deferens located just before the urethra -add buffers to the ejaculate -not present in all species |
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Vesicular Glands (seminal vesicles) |
pair of lobular glands with a grape like cluster appearance located near the bladder -greatly contribute to the fluid volume -contains nutrients Fructose and Sorbitol which are major sources of energy for sperm |
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Prostate Gland |
single gland located where the vas deferens and the urethra coverage in some species (horse) and in others it is embedded in the muscular wall surrounding the pelvic urethra -contributes little to the volume -contains high levels of inorganic ions |
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Bulbouretheral Glands |
paired glands located along with the urethra near its exits from the pelvis -in bulls, fluid is expelled prior to sex and flushes out the urine residue -in boars, fluid is a gel-like portion that seals the cervix and prevents semen from escaping |
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Penis basics |
male organ of copulation and deposits semen in the vagina or cervix (species dependent) of the female |
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3 Sections of the Penis |
1. The Glans: free extremity which is well supplied with sensory nerves 2. The body: main portion 3. Two Crura (roots): attach to the ischial arch of the pelvis |
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penis of bulls and rams |
both have a helmet shaped glans -rams: have a fillaform appendage that is an extension of the urethra that spins before ejaculation to clean the urethra |
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Boar penis |
boar glan is relatively small and looks like a cork screw allowing it to go into the cervix of the sow |
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Vascular Penis |
enlarges by retaining blood in erectile tissue during periods of sexual excitement causing an erection -blood leaves penis after ejaculation which decreases blood pressure and volume in penis -stallions |
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smooth muscle relaxed in vascular penis= |
erection |
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Fibro-elastic Penis |
penis is firm when not erect and only contain small amounts of erectile tissue -requires very little blood for erections -dont increase in diameter |
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Sigmoid Flexure |
ability to retract the penis completely into the body -S shaped bend in the penis that straightens during erections that lengthen the penis |
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what causes the seminiferous tubules to degrade and what does the degradation result in? |
-high heat that results in infertility if there for too long |
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thermosensors |
sensors in the scrotum that can detect outside temperature and then initiate the appropriate physiological response -wrinkling to decrease SA/ moving testes away from or to the body |
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tunica dartos |
smooth muscle that lines the scrotum |
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cremaster muscle |
external striated muscle that is located around the spermatic cord and allows testes to be pulled toward body |
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pampiniform plexus |
specialized vascular system that is a countercurrent blood supply in which cooler venous blood leaving the testes cool the warmer arterial blood entering the testes |
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Bilateral Cryptorchid |
both testes fail to descend and sterility occurs doe to the increased temperature from the abdomen
-animals aren't used to breed so they're often surgically castrated |
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where do the gonads develop in males and females? -how do they differ? |
-behind the kidneys --females (ovaries) stay in that location --males (testes) drop through the inguinal canals to the scrotum shortly following birth |
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Unilateral Cryptorchid |
only one of the testes descends -can still be fertile -can be surgically corrected -condition is inherited -can develop testicular tumors -castration is recommended |
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what is castration? |
the process of removing the testes -in livestock it prevents the inferior quality males from mating -removes source of testosterone which can lead to a decrease in bad behavior |
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what is the primary reason for castration? |
to influence the meat harvested from castrated males |
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if castrated early on... |
no secondary sex characteristics are developed which means greater meat quality |
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Vasectomy/ Epididectomy |
the surgical removal of a section of either the vas deferens or the epididymis -doesn't affect the production of male hormones and the animals with behave/ appear the same -males can help to identify females in heat |
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What is puberty? |
when an animal reaches a level of physiological maturity that permits conception |
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what are the two factors that influence puberty? |
1. Age: affected by genetic makeup and environmental factors (nutrition, climate and proximity of male) 2. Weight: determined by animals genetic makeup (age at which its weigh of puberty is obtained in influenced by nutrition) |
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basics of puberty in females |
-noted by the first estrus accompanied by ovulation -depends on production of follicle stimulating hormone (FSH), Leutinizaing Hormone (LH) and high enough levels of estrogen to induce follicle growth, maturation and ovulation |
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estrus defintion |
period of time when a female is sexually receptive to male -due to increased concentrations of estrogen and signals of approaching ovulation (heat) |
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Estrus Cycle Definition |
period of time from one estrus to the next |
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signs of estrus in -horses -pigs -cattle |
-horses: wink their vulva -pigs: do a stance that locks their legs to support a male -cattle: walk a lot and sometimes mount other females |
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menstrual cycle definition |
period from one menses to the next |
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Oogenesis |
production of the female germ cells/ oocytes -accomplished through meiosis which results in a gamete containing 1/2 the number of chromosomes found in somatic cells |
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Estrogen -source -function |
Ovarian hormone -source: follicle -function: estrus and mating behavior |
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Progesterone -source -function |
ovarian hormone -source: corpus luteum -function: maintains pregnancy |
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Prostaglandin -source -function |
uterine hormone -source: uterus -function: regression of the corpus luteum |
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Follicle Stimulating Hormone -source -function |
Pituitary hormone -source: pituitary -function: follicle development |
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Luetenizing hormone -source -function |
pituitary hormone -source: pituitary -function: ovulation and formation of the corpus luteum |
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when/ how does ovulation occur |
-when: near the end of estrus -How: follicle bursts releasing the oocyte into the oviducts and the corpus luteum forms as it bubbles off the follicle |
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how long is the follicular phase? |
2-5 days at the end of estrus and ovulation |
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Luteal Phase |
happens after the corpus luteum forms from the cells of ruptured follicle |
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corpus hemmorhagicum |
the bubble that forms just before rupturing |
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the sequences and timing of the events of the estrous cycle are controlled by the hormonal interplay of the ____________________________ |
hypothalamus-pituitary-ovarian axis |
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hypothalamus |
small region of the brain responsible for initiating the endocrine functions that control the estrous cycle |
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what hormone does the hypothalamus release and what does it do? |
-Gonadatropin-releasing hormone (GnRH) --is the first step in the cascade of hormonal events that coordinate ovarian function for repro success |
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Anterior pituitary gland |
GnRH acts on it -located directly below the hypothalamus and release luetenizing hormone (LH) and follicle stimulating hormone (FSH) into the blood stream |
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the release of GnRH from the hypothalamus occurs in a ____________________________ |
pulsatile manner |
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what is FSH inhibited by |
estrogen and inhibin |
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what is LH inhibited by |
progesterone |
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high concentrations of estrogen = |
initiation of LH surge and ovulation |
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estrus |
estrogen at peak |
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metestrus |
early stage of CL -low estrogen and high progesterone |
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diestrus |
intermediate stage with functional corpus luteum |
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proestrus |
regression of the CL with high LH which leads to growth of follicles -low progesterone -high estrogen |
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What is Gestation? |
the period of pregnancy for viviparous species that begins with fertilization of the oocyte and ends with parturition |
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short day breeders |
increased melatonin stimulates ovarian function (decreased light) -sheep, fox, deer |
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long day breeders |
decreased melatonin stimulates ovarian function -increase light with decreased melatonin -horses |
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prolactin |
hormone that is responsible for nesting behavior -stimulates milk production |
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parturition |
process of giving birth to offspring |
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process of parturition |
1. fetus secretes the hormone cortisol 48 hours before birth 2. triggers high progesterone in mom with decreased estrogen, oxytocin, prostaglandin, prolactin and relaxin 3. dilation of cervix (uterine contractions) 4. water breaks 5. explosion of fetus and placenta |
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dystocia |
difficulty during parturition (may need C-section) -fetus is too large -abnormal birth position -more common with males |
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what is the normal birth position |
feet and head between the legs first |
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are both ovaries functional in avians? |
no only the left -however if damaged early on the right one will take over |
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what is the yolks function |
to provide nutrients to the fertilized oocytes |
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what hormone is involved with yolk formation? |
FSH |
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what hormone causes the yolk to be ovulated |
LH |
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what is the stigma |
line of blood vessels in which ovulation occurs along |
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infundibulum |
captures the ovulated yolk -site of fertilization -30 minutes |
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how long is sperm viable in the avian tract |
120-160 hours |
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magnum |
thick portion of the albumen is deposited -2/3 hours |
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isthmus |
2 thin shell membranes are deposited along with water and mineral salts |
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uterus (shell gland) |
rest of the albumin is added (thin) and water is added via osmosis then calcification and pigment is added -18/20 hours |
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what is the shell composed of |
calcium carbonate (CaCO3) |
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what is added in the vagina |
the cuticle |
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how long does it take to complete the processes of making an egg |
24.5 hours |
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do poultry have an estrus cycle |
no |
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how long after laying an egg will it take for the hen to ovulate again |
30 minutes |
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pathogenies |
virgin birth |
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what does the male avian reproductive anatomy consist of? |
-internal testes -epididymis -ureter -vas deferens -kidney -cloaca |
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testes of avians |
-site of sperm production -internal -sperm production occurs at body temperature |
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epididymis of avians |
-smaller than mammals which leads to less sperm storage |
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Vas Deferens of avians |
leading from the testicles to the cloaca acts as a major storage site |
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what do roosters lack that contributes to lower seminal fluid concentrations |
-lack accessory glands |
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monotremes |
lay eggs after partial embryonic development -platypus, ekidna -only have a functional left ovary -half avian and half mammal -ekidna have a pouch that the baby stays in and develops after birth |
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Marsupials |
give birth to premature young and practice embryonic diapause -half monotreme and half placental -born at embryonic stage and crawl to the pouch using their arms where theyll attach to a teat -3 vaginas -can be fertilized quickly |
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Diapause |
the embryo grows to 100 cells and then stops and goes into a arrested state until it is ready to be born (environment, another joey present) |
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definition of artificial insemination |
a procedure in which semen is collected from the male and placed into the females reproductive tract |
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advantages of AI |
-maximizes genetic improvement with greater access to superior genetics -control over individual matings -reduced costs -control of reproductive diseases |
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disadvantages of AI |
-determining estrus of female |
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Dairy Cattle AI |
-70% of all cows -sexed semen to get females -frozen sperm -lactation doesn't suppress ovulation |
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beef cattle AI |
-20% of all cows -always out in pasture so we have a harder time determining when in estrus |
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Pigs AI |
-90% of all pigs -easy -related to the size of the operation with greater adoption in large industrial herds -fresh semen |
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Sheep AI |
-limited due to procedure requirements -fresh or frozen semen -arm up rectum to grab the cervix -hard to do because cervix is long and doesn't dilate -only do AI through laparoscopy |
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turkeys AI |
-almost all turkeys --breast size gets in the way |
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Broilers AI |
not widely adopted except in research and pedigree lines -easy and usually done once a week |
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llamas and Alpacas AI |
not widely used due to techniques in semen collection and preservation and conception rates -induced ovulators -use a dummy (sterile male) then AI |
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estrus synchronization |
controlling the estrus cycle so females express estrus around the same time -in order to induce= decreased estrogen, LH surge with a release of GnRH |
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why should we use estrus synchronization |
1. decrease the expense of time and labor for detection of estrus 2. success of embryo transfer |
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methods of estrus synchronization |
1. hormonal: induce ovulation to restart estrus cycle or suppress ovulation -CIDR 2. natural: weening (sows and cattle) |
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Embryo Transfer |
maximizes the use of the superior female genetics over her reproductive life time -super ovulate the female -collect and fertilize -introduce to other females |
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what was the original suggest for why animals lactate? -this was disproved and replaced with what? |
to maintain the temperature of the young -more recently we found that lactation evolved as a mechanism to maintain moisture of the egg and later became a food source |
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why did animals start lactating? |
so that they didn't have to go out and leave their young at home all vulnerable -high mobilization of the females body reserves |
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what does lactation enable? |
the young to be born relatively immature and it limited the weight of the fetus in utero allows the female to remain highly mobile during gestation -lets the mother secure food and run from predators |
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the complexity of mammary systems is coincident to the... |
complexity of the placenta |
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monotremes |
egg laying mammals with primitive mammary glands that do not have teats -166.2 mya -milk comes out of 150 million paired tubule glands on each side of the midline that open at the base of mammary hair -a lot more investment in lactation than gestation |
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is milk internally stored in monotremes |
no |
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marsupials |
144.7 mya -opossum, koala and kangaroo -give birth to live young after a very short gestation period -extensive lactation -pouched - 4 mammary glands and 4 teats |
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kangaroos lactation |
-can have both an embryo and a joey in the pouch -each teat can produce a certain kind of milk -female can terminate their young/ self abort if the environment is not favorable |
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opossum lactation |
-gives birth to 25 young but only has 15 teats --survival of the fittest -a lot of investment in lactation |
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placentals |
101 mya -90% of all mammalian species -complex placenta -greatest investment in gestation |
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alrtical young |
immature at birth and more reliant on maternal care -incapable of coordinated movements -eyes are closed -no hair or teeth -rodents |
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precocial young |
mature at birth and sense are fully developed -born with hair and teeth -capable of standing and fleeing from predators |
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location of teats |
1. pelvic/ inguinal region -goats, cattle, horses and giraffes 2. along the abdomen in parallel rows -sow, dog and car 3. Pectoral region -humans, gorillas and elephants |
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simple mammary gland |
all milk secreting tissues empty through a single teat opening -cows and ewes |
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complex mammary gland |
multiple openings within the teat and each correspond to a simple mammary gland -humans, horses, sows |
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each mammary gland (left/ right) is supplied with... |
-own nervous and lymphatic systems
-blood supply (no direct exchange of blood between the glands) |
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if one mammary gland receives treatment... |
all of the milk will have to be discarded because the blood circulates |
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how much milk does a cow udder hold? |
-usually 20-40 pounds --can hold up to 70 |
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for every gallon of milk ___ gallons of blood must circulate through the udder |
130 gallons |
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medial suspensory ligament |
provides a majority of the support that holds the udder -elastic tissue that originates from the middle and separates the 2 halves of the udder |
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lateral suspensory ligaments |
provide support to the udder -not elastic but is fibrous -originate about the udder and is located on each side and meet with the medial ligament across the bottom of the udder |
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alveoli |
primary functional units in the mammary gland responsible for milk synthesis and storage -spherical and arranged in clusters with lobules -lined with a single layer of epithelial cells (secretory) |
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as milk is synthesized, it is transferred to the ______________________ which acts as a major storage site |
-lumen of the alveoli |
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functions of epithelial cells |
1. absorbs nutrients and other precursors of milk from the blood stream 2. synthesize nutrients specific to milk 3. secrete milk components into the lumen of the alveoli |
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myoepithelial cells of the mammary gland |
surround the alveoli -muscular -contract and force all of the milk from the lumen of the alveoli into the ductal network which transports the milk to the gland and teat cisterns |
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teat cistern glands |
primary site of milk storage -annular rings to hold milk in |
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streak canal |
exit site of milk |
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furstenburgs rosette |
folds of tissue at the junction of the teat cistern and streak canal which compresses under milk pressure to prevent milk leakage -contains bactericidal proteins to protect from infection -lined with keratin to seal the streak canal in between milking |
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teat sphincter |
keeps the teat closed between milkings |
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do mammals lactate more than once? |
yes, since they reproduce more than once |
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cycles the mammary glands undergoes |
1. structural development (mammogeneis) 2. functional differentiation (lactogenesis) 3. regression (involution) |
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mammogenesis |
development of mammary gland -prenatal, peri-puberty, and post conception |
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lactogenesis |
functional differentiation represents active mammary tissue -initiation of milk synthesis and secretion (oxytocin, growth hormone and prolactin) |
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galactopoesis |
maintenance of milk secretion |
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involution |
return of the mammary gland to a non lactating state |
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how does the mammary gland aries |
from the thickening of tissue during embryonic development |
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parenchymal tissue |
composed of epithelial structures such as alveoli -secretory |
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stroma |
consists of connective tissue and blood vessels -a lot of white adipose tissue |
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mammary streak |
a single layer of cells on each side of the midline -distinct areas differentiate into buds -number and location of buds will determine the number and location of external glands observed in the adults |
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primary spout |
precursor of the teat and gland cisterns -evident by day 90 of gestation -secondary spouts form after |
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secondary spouts |
represents future mammary ducts and will be canalized shortly before birth |
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mammary fat pad |
supports late fetal and postnatal ductal development -observed at day 80 in cattle -day 16 in rodents |
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isometric growth |
growth at the same speed as the rest of the body -happens immediately after birth when ductal systems regresses |
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allometric growth |
rate of growth exceeds that of the body -signaled by ovarian function and estrogen production -corresponds to proliferation and expansion of the ductal system -stops when estrous cycle starts |
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excess energy during mammary growth |
impairs mammary development -reduces milk production during subsequent lactations |
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when is the greatest development of mammary glands |
during the last stage of gestation when there is also rapid fetal growth |
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prolactin |
released from the anterior pituitary gland and initiates and maintains lactation as parturition approaches |
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during maturation _______ and ________ peak to stimulate the mammary glands to come into a fully lactational state |
prolactin and oxytocin |
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persistance |
prolonged and steady production following the peak -necessary for high production rates over the entire lactation period |
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factors affecting persistance |
-genetics -nutrition -disease -frequency and completeness of milking |
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oxytocin |
hormone responsible for stimulating milk letdown -produced in the hypothalamus -released from the pituitary -acts on the myoepithelial cells causing them to contract |
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when is optimal milking time |
1-2 minutes after stimulation --after 7 minutes nearly all of the oxytocin is taken out by the liver and kidneys |
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epinephrine/ norepinephrine |
hormones that work in opposite of oxytocin -realsed when stressed, frightened or nervous -inhibit milk letdown by causing blood to go to extremities |
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involution |
following peak production mammary glad will undergo a gradual involution -decreasing in weight, volume and productivity -reduction in alveoli size and their synthetic capacity -extensive tissue degradation and almost complete loss of alveoli |
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lactation curve |
increase and decrease in milk production -plot of milk production over the duration of the lactation period --different in each species |
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factors influencing involution |
-will happen regardless of continual milking -stoping milking will cause it to happen more quickly |
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what is milk composed of? |
-water -triglycerides -lactose/ casein -protein -minerals -vitamins |
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milk composition varies |
by the environment and species |
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milk composition in marine animals |
more fatty for insulation from the cold environment |
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what is the primary carbohydrate of milk? |
lactose |
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lactose |
produced by the epithelial or secretory cells -made of glucose (provided by the blood stream) and galactose -need lactase to break it down (lactose intolerance) -contributes to milk volume |
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reduction in glucose= |
limits amount of lactose synthesized |
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milk allergy vs lactose intolerance |
milk allergy: response to the proteins in milk (casein or B-lactoglobin) Lactose intolerance: do not have the enzyme lactase |
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types of protein in milk |
1. casein 2. milk serum |
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casein |
80% protein in milk -produced by the mammary gland -many forms but all carry negative charges due to the phosphate group -responsible for the calcium content of milk |
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milk serum |
18% of protein in milk -provide amino acids for the synthesis of other proteins |
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colostrum |
first milk produced following parturition -has increased concentrations of proteins, fats, minerals and vitamin A -increased proteins due to the transfer of immunoglobins (antibodies in milk) which provide increased resistance to disease/ infection |
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passive immunity -colostrum only |
animal receives antibodes from milk -functionality depends on their absorption from the small intestine --pigs, horses, goats and cattle |
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placental transport + colostrum |
transfer of antibodies both in utero placental transfer and postnatally through colostrum -dogs, rats, mice and hamsters |
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placental transfer only |
only passive immunity through in utero -humans and rabbits |
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the intestine of neonate is able to... |
absorb large macromolecules such as immunoglobins as a consequence of immaturity |
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gut closure |
intestine matures so its no longer able to absorb immunoglobins -this is why they need colostrum early (quality of colostrum also decreases) --24 hrs in calf, horse, dogs and cats --36 hrs in pigs |
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factors affecting gut closure |
-failure to suckle right after birth -production of colostrum exceeds window of gut closure |
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IgG |
most important antibody -nonspecific antibody |
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Lipids in milk |
90% as triglycerides, 10% as cholesterol and phospholipids -vary in length and saturation |
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sources of milk lipids |
1. circulation -originating from diet or mobilization of body fat 2. production by mammary tissues |
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characteristics of milk fat depend on the |
source of the fatty acids |
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long chain fatty acid |
absorbed from the blood stream |
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short/ medium chain fatty acids |
synthesized from mammary tissue |
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ancestor of all cattle |
Auroch -survived until 1672 |
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Christopher columbus |
accredited with the introduction of cattle to the western hemisphere during his 2nd voyage in 1493 |
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cortez |
in 1593 brought cattle to Mexico and thees were then distributed throughout the southwestern US -led to the feral longhorns |
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jamestown colony |
imported cattle to North America in 1611 -then imported a ton more -migrated west with pioneers |
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longhorn cattle wipeout |
-crossed with shorthorns that were brought in -were used to feed people after WWII |
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shorthorns didn't do well in western conditions so... |
they were crossed with herefords to improve their hardiness |
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black baldy |
hereford x angus |
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feeding as technology advanced |
-orgininally they were raised on pasture and forages -as technology in harvesting grains advanced, we started feeding them this grain |
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results of feeding the cattle grains |
-increased the number of cattle -increased market price -created concerns that they were getting too fat |
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breed revolution |
occurred in 1970 and resulted in new breeds imported for commercial production of cattle for the feed lot industry -most cattle today |
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purebred cattle |
crucial to direct genetic change -purity of ancestry -pedigrees recorded in their breed registry -1900's trend |
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commercial/ crossbreed |
typically crossbreeds -some herds of non-registered single breeds exist -not registered/ pedigreed -90% of cattle |
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British breeds |
bos tarus -originated in the British isles -maternal breeds due to their moderate size, high fertility, extended longevity and high-moderate milk production -early maturity -less muscular |
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angus |
British breed -originated from Scotland -developed exclusively for meat -black/ red in color --black is dominant and under a separate registry -pulled and have a smooth coat |
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hereford |
British breed -originated in England -red with white faces (white on legs, abdomen and tail) -originally horned but are pulled by a genetic mutation -vigorous and hardy |
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shorthorn |
British breed -originated from northern England -dual purpose (meat + milk) -horned or pulled -red, white or roan -reproductive efficiency, longevity and milk production |
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Continental/ exotic breeds |
bos tarus -from Europe -paternal/ terminal (grow well) -rapid growth rate -heavy muscling -lean -large -dual or tri purpose |
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simmental |
Continental -from Switzerland -triple purpose -red, yellow, white, grey and black (w/ or w/o spots) -pulled or horned -large and docile -rapid growth rate, thick muscling, lean, maternal and milk production |
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Limousin |
Continental -from France -oldest domesticated breed -"golden cattle of france" -red/ gold/ black -shorter necks, small heads and large foreheads -paternal, large loin, lean |
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Charolais |
Continental -France -limited # due to restraints imposed -pink skin with white-light straw colored fur -pulled or horned -large and heavy muscling -rapid weight gain -very red muscles that are lean and tender -used in cross breeding |
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Zebu |
Bos Indicus -mostly american brahman mixes -greatest genetic influences worldwide -humped which is a result of the thoracic vertebrae and extended dewlap -heat and insect repellent -adopt well to arid environment |
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American Brahman |
Bos Indicus -imported from India -grey, red or black -crucial to creation of crosses of bos indicus- bos tarus -more in southern regions -reach puberty at later ages -reduced growth rates -less muscling |
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Brangus |
Bos Indicus -5/8 angus and 3/8 brahman -recognized as purebred with in their own registry -small hump = better quality |
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beefmaster |
Bos Indicus -50% brahman, 25% hereford and 25% shorthorn |
