AnSc 1101 Introductory Animal Science Reproduction

Bovine ovaries Female Organs of Reproduction Ovaries Produce eggs (ovum -singular, ova –plural) 100,000 immature ova in ovary at birth Bovine ovaries

Equine Maturing follicular Ovaries for different species can appear quite different in appearance. The ovulation fossa is the ventral depression in the equine ovary.  Note that one of the follicles appears to be growing toward the fossa. 

2. Produce hormones a. estrogen – primary female sex hormone. Causes estrus behavior. Highest with mature follicle. b. progesterone – produced by the corpus luteum (C.L.) or yellow body. Needed to maintain pregnancy. c. Testosterone – 5% of amount produced by testes.

Diagram of a C.L. Mature Follicle

1. transports egg from ovary to uterus - about 5” long. B. Oviducts 1. transports egg from ovary to uterus - about 5” long. 2. infundibulum – funnel-like structure 3. fertilization – takes place 1/3 of way down the oviduct. Egg remains in oviduct 2 to 3 days but must be fertilized within 10 hours of ovulation. The infundibulum captures the egg at time of ovulation. Site of fertilization

C. The uterus provides environment for fetus - secrets nutrients until placentation takes place. - provides exchange of nutrients with placenta. 2. produces prostaglandin – when not pregnant, to regulate estrus cycle by causing regression of the C.L.

Horns are less pronounced in the equine. Equine Bovine

Note in swine how the vagina funnels into the crevix Note in swine how the vagina funnels into the crevix. The cervix does not have interlocking rings as in ruminants. This makes AI easier. Canine, Feline Porcine

human equine ruminant swine

D. The cervix 1. comprised of connective tissue – relaxes a little during estrus and completely during parturition. 2. serves as gateway between vagina and uterus – secretes a cervical plug to keep pathogens out of uterus. Cattle, sheep, and goats have “rings” in the cervix.

E. The vagina 1. Where semen is deposited during natural service; except in pigs where it is deposited in the cervix. 2. Serves as part of the birth canal.

- acidic to kill bacteria - clear, crystalline mucus during estrus E. The vagina 3. Secretes muscus - acidic to kill bacteria - clear, crystalline mucus during estrus 4. Also serves the urinary tract. The clear, crystalline mucus during estrus is a good indication that the animal is on estrus.

swell during time of estrus F. The vulva 1. outer lips of reproductive tract swell during time of estrus - swelling is especially pronounced in swine. - the vulva opens and closes in a winking fashion when a mare in estrus is excited.

The broad ligament holds the reproductive tract in place.

II. Reproduction in Poultry Females A. Differences between birds and mammals B. Gross Anatomy 1. Lays hard shelled egg 2. only 1 functions ovary. 3. ZZ=male, ZW= female. 4. no estrus cycle. 5. no cervix. 6. embryo develops outside body. 7. birds do not have mammary glands. 8. viability of semen in tract, 10 days for chickens and 30 days for turkeys.

Yolk 3,000 – 4,000 ova Germ cell Infundibulum: 3-4” long 15 minutes Fertilization takes place Sperm remains viable: 10 days chickens 30 days turkeys

Secretes the white (albumen) Magnum: 3 hours, 15” Secretes the white (albumen) Isthmus 1.5 hours, 4” Puts shell membrane around egg Magnum Isthmus

Vent Uterus: shell gland 21 hours Shell formed Pigmentation added 30 minutes after egg is laid another ovum is ovulated Vagina – 2” Cloaca Vent

D. Egg abnormalities Double yolk (two ovum ovulated at once). Soft shell (lack of calcium in diet or does not stay in uterus long enough). Blood spot (small amount of bleeding at time of ovulation). Yolkless egg (yolk was not ovulated). Green eggs (birds eating grass). Small egg inside of large egg.

BLOOD SPOTS Also called meat spots. Occasionally found on an egg yolk BLOOD SPOTS Also called meat spots. Occasionally found on an egg yolk. Contrary to popular opinion, these tiny spots do not indicate a fertilized egg. Rather, they are caused by the rupture of a blood vessel on the yolk surface during formation of the egg or by a similar accident in the wall of the oviduct. Less than 1% of all eggs produced have blood spots. (http://www.georgiaeggs.org/pages/bloodspots.html)

Both chemically and nutritionally these eggs are fit to eat Both chemically and nutritionally these eggs are fit to eat. The spot can be removed with the tip of a knife, if you wish

III. Male Organs of Reproduction A. Testicles 1. produce sperm: larger testes = more sperm - sperm production takes about 45 days - young spermatids most sensitive to heat - trillions of sperm produced in a lifetime 2. produce testosterone - male sex hormone - causes male libido - causes secondary sex characteristics Secondary sex characteristics are those phenotypic characteristics that make males different than females.

B. Epididymis storage of sperm – sperm stored in tail of epididymis until ejaculation. head body tail

Cytoplasmic droplet of immature sperm. B. Epididymis (cont.) maturation of sperm – sperm that enter epididymis are not capable of fertilization. Cytoplasmic droplet of immature sperm. The cytoplasmic droplet works its way down the tail as the sperm matures in the epididymis.

1. protects the testicles 2. maintains testicles at lower temperature C. The scrotum 1. protects the testicles 2. maintains testicles at lower temperature 3 - 7 F lower in bulls 9 - 13 F lower in rams Picture: Measuring scrotal circumference which is related to sperm production.

3. Mechanism of temperature regulation Cremaster muscle raises and lowers the testes. Tunica dartos contracts when cold to reduce surface area.

3. Mechanism of temperature regulation Cremaster muscle raises and lowers the testes. Tunica dartos contracts when cold to reduce surface area. Sweat glands on scrotum

3. Mechanism of temperature regulation Cremaster muscle raises and lowers the testes. Tunica dartos contracts when cold to reduce surface area. Sweat glands on scrotum Pampiniform venous plexus is a heat exchange system. The arteries come out of the body at 100 degrees and exchange heat with the blood veins coming up from the testes at 95 degrees.

Inguinal ring A crytorchid is when a testes (unilateral) or both testes (bilateral) do not descend down into the scrotum during late fetal development. Order of frequency – pigs, horses, cattle (least).

D. The vas deferens 1. - passage way for sperm from epididymis to the urethra 2. - ampulla: enlarged end of vas deferens as they near the urethra (bulls, stallions, rams)

E. Accessory glands 1. Vesicular glands (seminal vesicles) – provides energy, buffers to protect semen from acidic vagina, and adds volume to semen ( H2O) 2. Prostate 3. Bulbourethral seminal vesicles - appear like a cluster of grapes

2. Prostate – contributes inorganic ions: E. Accessory glands 1. Vesicular glands 2. Prostate – contributes inorganic ions: sodium, chlorine, calcium, magnesium The prostate encircles the urethra. The prostate encircles the urethra. It often enlarges in older men and dogs which causes problems with urination.

E. Accessory glands 1. Vesicular glands 2. Prostate 3. Bulbourethral (Cowper’s gland) – provides the gel-like portion of semen usually toward the end of the ejaculation. Largest in boars. Gel is spermicidal.

Vas deferens urethra bladder

Vas deferens urethra sperm bladder

Vas deferens Sperm Semen bladder Sperm is mixed with accessory gland fluid and the two combined is known as semen. bladder

F. Penis 1. organ of copulation in males 2. bulls, boars, and rams have S-shaped bend in the penis to allow retraction into body and extension during copulation Retractor muscle sheath

3. stallion’s penis contains more erectile (spongy) tissue Bull Boar Ram Stallion

Boar’s penis has a corkscrew tip that locks into the grooves in a sow’s cervix.

The ram’s penis has an appendage that swirls around spraying semen around the vagina of the ewe. Purpose unknown.

G. Reproduction in Male Poultry 1. testes in body cavity 2. vas deferens open into small papillae in the cloaca 3. male fowl do not have a penis – most birds press their cloacae together. Water fowl have a phallus. testes

H. Unique characteristics of a dog’s penis: 1. Within the penis is a small bone called the os penis. It helps to give support during intromission. 2. The base of the penis contains a swelling called the bulbus glandis which “ties” the male dog and bitch together during mating. The tie may last from a few minutes to an hour. os penis

I. Unique characteristics of a cat’s penis The male cat's penis has spines which point backwards. Upon removal of penis, the spines rake the walls of the female's vagina. The female needs this stimulation for ovulation to begin.

“No matter how much cats fight, there always seems to be plenty of kittens.” Abraham Lincoln, 16th president.

IV. Estrus Cycles A. Definitions: 1. Estrus – time when female is receptive to the male. 2. Estrus cycle – period between estruses.

ovary – mature follicle uterus Ready for pregnacy Estrus behavior Hormone Source Target Result GnRH hypothalamus Anterior pitutary FSH or LH released FSH anterior pituitary ovary Follicular growth LH ovary - follicle Ovulation estrogen ovary – mature follicle uterus Ready for pregnacy Estrus behavior progesterone ovary – C.L. Maintains pregnancy Restricts GnRH release prostaglandin C.L. on ovary C.L. regresses Hormones are the messages from one organ to another telling them to do an action.

Simplified view of the estrus cycle. FSH

This modification denotes that there are actually 3 follicular waves during an estrus cycle. The first two do not result in a mature follicle because of the presence of progesterone. FSH

C.L. Ovary midcycle. Has an active C.L. A wave of follicles are developing but probably will not go to marurity. follicles

C. Time sequences of cycles Duration of Estrus Length of Cycle Time of Ovulation Cattle 8-20 hours 21 days 10 hours after estrus Sheep 30 hours 17 days Late estrus Horses 4-8 days 22 days 1-2 days before end of estrus Swine 2-3 days 20 days Mid-estrus Goat 30-40- hours Few hours after end of estrus Rabbit 13 days 8-10 hours after mating Cats 6-7 days 18 days Stimulated by mating Dogs 6-12 days 6 months 1-3 days after estrus begins Rabbits really do not show typical estrus behavior but are receptive to the male 13 of the 17 day estrus cycle.

V. Artificial Insemination A. History 1322 1780 Italy – AI demonstrated with dogs 1900 Russia – AI successful with cattle, sheep, horses, and birds. 1914 – Artificial vagina used to collect dogs. 1322 AI used in Arabians

Denmark: 1st AI cooperative for cattle 1st cow bred AI in U.S. at University of Minnesota – had calf at Duluth farm. (claim shared with Rutgers) 1938 AI Cooperative formed in New Jersey AI Cooperatives started in Minnesota Old dairy barn The first cow to conceive to AI in North America was bred in the old dairy barn on the St. Paul campus. The pregnant cow was transported to a dairy herd that the university had near Duluth to have the calve – away from the media in case something went wrong. At one time there were over 100 AI cooperatives in the U.S.

b. Antibiotics prevent bacterial growth. 1940’s a. University of Wisconsin – developed extender of egg yolk and phosphate which allowed semen to be cooled to 5º C and remain viable for 3 – 4 days. b. Antibiotics prevent bacterial growth. 1951 England: glycerol added to allow freezing with dry ice (-79º C). First calf born from frozen semen.

1953 1st calf born from frozen semen in the U.S. (Frosty) 1956 ABS, DeForest, Wisconsin pioneered the use of liquid nitrogen to store semen at -320º F. 2004 Sexed semen became commercially available in the U.S.

Advantages of AI 1. Greater genetic progress a. Transport semen b. Progeny testing c. More offspring from outstanding animals

Advantages of AI 1. Greater genetic progress a. Transport semen b. Progeny testing c. More offspring from outstanding animals 2. control venereal diseases 3. improved record keeping 4. reduced cost of housing males 5. fewer dangerous males 6. control over which females get bred 7. greater variety of genetics available

Disadvantages of AI 1. Must detect females in estrus or have synchronization program 2. Timing of insemination can be difficult to determine – may need two inseminations on horses and pigs. 3. Need trained personnel 4. May have lower pregnancy rate?? 5. Cost of semen and supplies.

D. Extent of AI used for different species/industries in the U.S. 1. Dairy 65 – 75% 2. Beef 7 – 10% 3. Swine > 90% 4. Horses >50% in MN 5. sheep and goats <1% 6. Chickens <10% Turkeys 100% Dogs increasing The text says that the % beef bred AI is higher but that is doubtful. The figures for AI in horses in MN comes from the MN Vet School.

AI in beef cattle can be a real challenge!!!!!!!

Characteristics of Ejaculates Volume (ml) Sperm 106/ ml Total Sperm Dairy Bulls 7 1250 8.7 B Beef Bulls 5 1500 7.5 B Rams, Bucks 1 2000 2.0 B Boars 225 125 28.1 B Stallions 90 125 11.2 B Dogs 10 3000 30.0 B Cats 1.5 15000 33.75 B Dogs and Cats from Fundamentals of Animal Science by Colin Scanes.

VI. Cattle AI The U.S. exports a lot of semen.

Over 500 progeny tested Holstein dairy bulls available to U. S Over 500 progeny tested Holstein dairy bulls available to U.S. dairy producers.

84,200 daughters as of February 2012 +854 lbs. milk + $684 Net Merit Many species have at a measure of longevity to their genetic evaluations. Even though the heritability of Productive Life is only about 8% in dairy cattle, it is an extremely important trait. The daughters of the bull above remain in the herd about 6.7 months longer on average than a bull with a PTA of “0” for Productive Life.

Semen Collection The artificial vagina consists of a large rubber tube lined with a water holding jacket. A receptacle for collecting the semen is attached to the end of the tube.

A. Semen Collection The most common method of collection is the artificial vagina as this results in the highest quantity and quality of semen.

As the bull mounts a steer tied to a fence, the technician directs the penis into an artificial vagina.

Semen Evaluation After the semen has been collected, it is examined in the lab under a microscope for motility and morphology.

After the semen sample passes a thorough evaluation, it must be processed using an extender. The extender dilutes the semen sample so it can be divided into several units for the fertilization of many eggs. The extender also dilutes the waste products produced by the sperm so the sperm remains viable.

Processing the Semen Extender also provides nourishment and protects the semen after it has been frozen. Common extenders added to semen include milk, egg yolk, glycerine, and antibiotics. New extenders are now developed that contain no animal products!

Freezing the Semen Semen is frozen at a constant rate until it reaches a temperature of –320 F. Semen is stored in liquid nitrogen tanks to preserve it.

Semen must contain at least 40 million cells per cc before freezing and 12.5 million cells per cc after thawing to be used for AI.

B. Timing of insemination 1. Heat detection a. Standing to be mounted is primary sign.

1. Heat detection (cont.) b. Secondary signs include mounting other females, increased activity, a clear crystalline discharge from the vulva.

2. Heat detection aids a. Kamar patches Useful on cows you suspect may be coming into heat, but not yet showing standing heat. Cost ~ 1.00/ apiece Should be used as tool to supplement visual detection not replace it

Tattle Tale This extremely accurate 12-hour timer precisely pinpoints the time a cow begins standing estrus and counts the number of three-second standing mounts the cow accepts. The device automatically stores in memory the three most recent series of mounting activity (up to three 12-hour series) and can easily be played back for reference.

Tail Chalking Can be prone to errors Less labor intensive than observation CHEAP

The patch is placed on the rump and transmits to the computer when the first mount happened, how many mounts and the last mount. Very accurate but somewhat expensive and some have had problems with the patches falling off.

Activity monitors downloaded into a computer program.

Other Methods teaser gomer bulls chin ball marker steroid-treated cows

Other Methods teaser gomer bulls chin ball marker steroid-treated cows Pedometers

Artificial Insemination Ovulation and Fertilization 3. Cows should be inseminated 12 to 16 hours after initiation of estrus. Artificial Insemination Onset of Heat Ovulation and Fertilization Sperm Capacitation 0 12 16 20 24 25 33 Hours Sperm have to be in the female tract for a few hours before they are able to fertilize the egg. This is called sperm capacitation.

C. The insemination process Semen is thawed by placing in 95 degree F water bath. The straw is placed into the end of the AI rod and a protective sheath is put over the rod. The plunger is locked into place. Bovine semen comes is ½ and ¼ cc straws. The ¼ cc straws can be thawed in a clenched fist.

Locating the Cervix The technician should insert one hand into the cow’s rectum to locate the reproductive tract and cervix.

Cleaning the Vulva The vulva should be cleaned with paper towels to avoid contaminating the reproductive tract when inserting the AI rod into the vagina.

Inserting the Insemination Gun Once the cervix has been located, the AI rod is inserted through the vagina into the reproductive tract. The rod must be passed through the three muscular rings of the cervix and into the body of the uterus.

Depositing the Semen Once the technician is sure the rod has passed through all three rings of the cervix, the semen is deposited into the body of the uterus.

Oviduct Site of Fertilization Uterine horns Oviduct Site of Fertilization Ovary Uterine body ‘TARGET’ Cervix

VII. Swine A.I.

% of Sows Bred A.I. 1990 7% 1997 50% 2010 >90%

Boars collected 2 to 3 times per week. 12 inseminations per ejaculate. Assuming 2 inseminations per sow equals greater than 500 sows serviced per boar.

A.I. Advantages in Swine Saves time. Fewer boars to maintain. Mate animals of different sizes Works for producers of all sizes More offspring from boars of top genetics

Large operations may purchase large amounts of semen from a stud for about $8 per dose without worrying about which individual boar it may have come from. Semen doses may actually be a mixture of semen from different boars of the same breed or line. Semen from top purebred boars sells for from $50 to $200 per dose.

Procurement of Boar Semen Semen purchased from commercial studs Semen collected from boars on site.

An artificial vagina

Boar being used for estrus detection.

Boar in remote control cart used for estrus detection.

Old fashioned method of insemination but may be used again if gestation grates are outlawed. Inseminator is putting pressure on the gilt’s back so that she stands. He is further stimulating her by working her flank.

With a boar present, the sow’s reproductive tract draws in the semen. Sows in gestation grates. Boar (not seen in picture) in front of sows increases conception rate.

VII. Artificial Insemination in Horses

A.I. may be less strenuous for your horses.

A. Stallion is being introduced to the breeding mount.

1. Mare in estrus is facing the stallion at the other end of the breeding mount.

2. The stallion’s penis needs to be directed into the AV.

The stallion is breeding the AV.

3. The stallion is ejaculating as indicated by the flagging of his tail.

4. The stallion should be allowed to dismount when he is ready.

5. Washing a stallion prior to collection.

Ground collecting a stallion Ground collecting a stallion. After training this can be a one person operation.

Advantages of ground collecting is that it can be done anywhere and may be successful for stallions that refuse to mount.

Stallion Condom

Large numbers of sperm are needed than for cattle. B. There are many commercial extenders available. Need .5 billion sperm per dose for fresh semen. 1 billion sperm per dose if using chilled semen.

C. Mare preparation. 1. The mare should be hobbled or placed in stocks. 2. The tail is wrapped. 3. The perineal area is scrubbed, starting central and working outward. 4. This scrubbing process is repeated.

D. The semen is drawn into the syringe through the insemination pipette.

E. A sterile, lubricated glove is introduced into the mare’s vagina along with the pipette

The gloved pipette is placed over the end of the pipette prior to introduction of the pipette into the vagina.

The index finger is used to find the opening to the cervix and guides the insertion of the pipette.

The plunger is slowly depressed so that semen is deposited into the body of the uterus. .

The syringe may be unhooked and rehooked so that 2 cc of air can push the remaining semen out of the pipette.

AI restrictions The Jockey Club does not allow the use of A.I. or E.T. (Thoroughbreds)

Most other breeds have relaxed restrictions on AI and in many cases encourage it.

IX. Dog A.I.

The artificial vagina for dogs is quite simple.

Hand pressure is used to simulate the dog’s penis.

Semen is deposited through the cervix into the body of the uterus. A picture of some abnormal dog sperm. Semen is deposited through the cervix into the body of the uterus.

Sheep A.I. Sheep semen is available but the market is very limited.

Number of Motile Sperm / Insemination 106 Needed for success AI Deposit site Fresh Chilled Frozen Vagina 250 300 500 Cervix 175 200 300 Transcervical 75 75 100 Intrauterine Laparoscopic 40 40 40 Intrauterine laparoscopic is when a slit is made on the belly and sperm is injected right into the uterus.

XI. Estrus synchronization Estrus synchronization is a management tool with several different procedures No matter how well used conception rate is generally not increased. Increases pregnancy rate by increasing service rate

Synchronization Products Prostaglandin (PGF) Lutalyse Estrumate IN-SYNC

X X Follicle Corpus Luteum Ovulation Progesterone Prostaglandin causes the C.L. to regress. Progesterone level decreases. The Hypothalamus then releases GnRH causing the anterior pituitary to release FSH and LH which causes the follicle to mature and ovulate. Ovulation Progesterone

Synchronization Products Progestins Melengestrol Acetate (MGA) Norgestomet CIDR

X  Follicle Corpus Luteum Ovulation Progesterone A continuous supply of external progesterone prevents the follicle from maturing or ovulating until the external supply of progesterone is stopped. Ovulation Progesterone

Synchronization Products Gonadotropin Releasing Hormone (GnRH) Cysterelin Fertagyl Facterel

 Follicle Corpus Luteum Ovulation Progesterone GnRH causes the release of FSH and LH from the anterior pituitary which causes the follicle to mature and ovulate. Ovulation Progesterone

A. Synchronization in cattle 1. prostaglandin causes regression of the corpus luteum a. advantages cheap – about $2.00 per dose b. disadvantages 1. Will cause an abortion if mistakenly given to a pregnant animal. 2. Must have an active C.L. to be effective (days 5 – 18 of estrus cycle) 3. Come into estrus 2-5 days after injection 3. They come into heat offer a 3 day period. Other programs synchronize the animals into a much tighter window.

Melengestrol acetate (MGA) and Prostaglandin a. MGA is fed for 14 days to non-lactation animals. b. 17 days after MGA is taken from feed, an injection of prostaglandin is given c. most females show estrus in 2 to 3 days

Progesterone vaginal insert (CIDR) and prostaglandin insert CIDR in vagina ($8) day 6 inject prostaglandin day 7 remove CIDR Estrus 2-3 days Can be used on lactating and non-lactating animals. Synchronizes animals into a tight estrus window.

Day 7 – inject Prostaglandin Day 9 – inject GnRH 4. OvSynch Day 0 – inject GnRH Day 7 – inject Prostaglandin Day 9 – inject GnRH 16 hours later inseminate Animals ovulate and are fertile without showing estrus. Works best on lactating animals.

Presynch and OvSynch – like OvSynch, except prostaglandin, injections are given 26 and 12 days prior to the first GnRH injection Note that there are a total of 5 injections prior to insemination with this protocol but it is more effective that OvSynch alone.

Synchronization in Mares 1. Regumate (altrenogest) a. progestin fed for 14 days with estrus 2 to 4 days after withdrawal b. may be fed to prevent estrus

2. Using artificial lighting to bring mares into estrus This is not really synchronization but bringing mares into estrus out of season. Artificial light is used to bring mares into estrus is February rather than having to wait until April or May. For the show or racing it is advantageous for foals to be born in January.

C. Synchronization in Swine Prostaglandin effective day 12 to 18 Feed Matrix for 14 days then remove and gilts come into heat 2-4 days later 3. Natural synchronization a. sows come into estrus 3 to 4 days after weaning b. move group of gilts – estrus 3 to 4 days later

XI. Superovulation and Embryo Transfer in Cattle A. Donor Preparation 1. FSH is injected beginning on day 8 of the estrus cycle and continued every 12 hours for a total of 6 injections. 2. Prostaglandin injected at same time as 5th or 6th FSH injection 3.Cow comes into estrus 2 to 3 days later 4.Inseminate toward the end of estrus. Two inseminations may be given 12 hours apart. What does the FSH do? Causes multiple follicles to develop. What does the prostaglandin do? Causes regression of C.L. so that animals comes into estrus and ovulates.

B. Collection of embryos 1.Collect 7 days after insemination

2. Embryos are examined under a microscope 3. Good embryos are put into recipients or frozen Number of good embryos from a flush will range from 0 to 35. Zero is the most common number. Average is 6 to 8. This may sound confusing but about 25% of the time no embryos are recovered.

Putting embryos into recipients Reproductive cycle must be synchronized with the donor: day 7 of cycle 2. A pipette is used and embryo is deposited in uterine horn on same side as the CL Embryos as they look under a microscope.

In vitro fertilization 1. Ova are aspired directly from ovaries a. can be done bi-weekly b. can be done on pregnant cows c. can be on from ovaries taken from dead or dying cows 2. Oocytes are fertilized 1 day after collection in a dish using a small amount of semen. 3. Embryos are cultured for 7 days and then placed into recipients.

E. Cloning

F. Importance of Embryo Transfer: 1. Dairy Cattle - <1% of calves - >80% of bulls going into A.I. 2. Beef Cattle - 10% of registered Angus calves 3. Sheep – almost none 4. Swine – almost none 5. Horses – increasing but still some breed restrictions.

XII. Using hormones to manipulate reproductive cycle 1. Induce parturition Swine – inject prostaglandin within 3 days of due date and sows farrow about 26 hours later. Cattle and sheep – inject dexamethasone plus prostaglandin. Parturition in 25 to 42 hours.

2. Treat anestrus – inject GnRH to cause. FSH and LH to be released 2. Treat anestrus – inject GnRH to cause FSH and LH to be released naturally. 3. Treat follicular cysts – GnRh causes nature release of LH which will cause ovulation. Anestrus is when an animal should be cycling is not. A follicular cysts is a mature follicle that just fails to ovulate.

4. Treat luteal cysts – inject prostaglandin 5. Abort unwanted pregnancies inject prostaglandin. This is most effective if given early in the pregnancy. Usually not effective if animal is over half way through gestation. A luteal cysts is a C.L. that just fails to regress naturally.

Low libido in boars a. Testosterone injection may help inexperience boars get started. b. A injection of prostaglandin will get lazy older boars to mount the dummy for collection. Mode of action is unknown.

7. Short cycle cows or mares -. Prostaglandin effective day 6. through 7. Short cycle cows or mares - Prostaglandin effective day 6 through day 18 of the estrus cycle. In estrus 4 to 5 days later. Used to short cycle a mare. For example, my wish to give an injection on day 7 of the estrus cycle to bring her into estrus 10 day sooner than she would naturally.

8. If cows are fed once per day in the evening, they will calve during daylight hours. Naturally, cows tend to calve during the night which means lost sleep if the herdsperson wishes to be present.

XII. Growth and Development A. Gestation Length Days Cattle 280 9 months plus 10 days Sheep 145 Horse 335 - 11 months Goat 149 Swine 114 3 months, 3 weeks, 3 days Dogs and Cats 58-70

1-2-4-8-16-32 numbers of cells as the cell divide 1-2-4-8-16-32 numbers of cells as the cell divide. The zona Pellucida remains intact and the embryo does not increase in size but the cells get smaller.

Inner cell mass becomes the fetus. Trophoblast becomes the placenta. The zona pellucida disintegrates and the blastocyst elongates and begins to get larger. Inner cell mass becomes the fetus. Trophoblast becomes the placenta.

C. Timing of embryonic development for different species 1 cell 8 cell Enter uterus Blastocyst Placentation Cattle 24 hrs 3 days 3.5 8 35 Horse 24 3 5 6 28 Sheep 2.5 7 25 Swine 14 – 16 2 16 The relative timing of development is proportional to the species’ gestation lengths

D. Differentiation – cells form specific organs Characteristic Cattle Swine Heartbeat 22 16 Fore limb bud 25 18 Hind limb bud 28 19 Lens of eye 30 21 Facial features 45 When differentiation is completed the embryo is then referred to as a fetus.

E. Growth of the bovine embryo – fetus Days of Gestation Wt. (Kg) 0 – 30 .0005 31 – 60 .0059 61 – 90 .0726 91 – 120 .531 121 – 150 1.6 151 – 180 3.8 181 – 210 9.5 211 – 240 17.7 241 – 270 28.6 271 – 300 39.9 45 days becomes a fetus. 110 days tooth eruption begins. 182 days tail-tip hairs present. 230 days – full hair coat. Three fourths of the growth occurs in the last trimester.

F. Growth Curves Maturity Growth slows as animals reach maturity.

F. Growth Curves muscle fat bone Animals may continue to put on fat after the skeleton and muscle stops growing. bone