ANS 221 Lab Practical 2

What are the placenta types?

Cotyledonary Placenta

Zonary Placenta

Discoid Placenta

Diffuse Placenta

What do you have to identify on the cotyledonary placenta?

Fetus

Caruncle (maternal side) - think moms drive cars

Cotyledon (fetal side) - think baby in cot

Chorioallantois

Placentome

What do you have to identify on the zonary placenta?

Central girdle

Chorioallantois

What to identify on the porcine fetus and placenta?

Fetus

Chorioallantois (outer layer)

Amnion (surrounds fetus)

Necrotic tips

*Porcine fetus is diffuse

Function of chorioallantois and amnion

Chorioallantois: gas exchange and waste

Amnion: fluid-filled protection sac

Table 1 1/4

Cow placenta (cotyledonary placenta)

Cotyledons

Caruncles

Table 1 2/4

Cow placenta (cotyledonary placenta)

Caruncles

Table 1 3/4

Cow placenta (cotyledonary placenta)

Cotyledons

Attached to chorioallantois

Table 1 4/4

Cow placenta (cotyledonary placenta)

Cotyledons and Caruncles attached = Placentome

Table 2 1/2

Ewe placenta + fetus

Table 2 2/2

Ewe placenta + fetus

Table 3

Cat (zonary placenta) or dog

2 dif fetuses

Can semi see central girdle - it is lighter band

Chorioallantois is most free tissue - prob won’t be on this

Table 4 1/3

Pregnant sow (diffuse placenta) - uterus

Large uterine horns

Ovary with bunch of CLs b/c pregnant

Necrotic tips between each to prevent disease from traveling to kill litter

Middle thing is amnion

Table 4 2/3

Pregnant sow (diffuse placenta type) - uterus

Rugae: maternal side of placenta in pigs - think moms like reggae

-Textured

Areola: fetal side of placenta in pigs

Table 4 3/3

Pregnant sow (diffuse placenta type) - uterus

Table 5 1/3

Left is porcine fetus

Right is bovine fetus

Table 5 2/3: Bovine fetal-rump length graph. What measurement? And what is the one that was out?

*This is in cm!

Around 85 days of gestation

Table 5 3/3: Porcine fetal-rump length graph. What measurement? And what is the one that was out?

*This is in mm!

Around 60 days gestation

Table 6

Pigs (diffuse placenta)

Corioallantois is outside fetus + is vascular

Necrotic tips on ends

Amnion directly on fetus

Lab Equipment Table

Left to right:

AI Rod; Cane; Goblet; Semen Straw; Ampules

Also liquid nitrogen tank was there

What is embryonic development called?

Embryogenesis

What forms day 7-9?

Blastocyst

Embryonic development stages drawn out

Another diagram with more embryonic stages and days they occur

Stages from around around 16 cell stage?

After 16 cell stage: morula forms (packed mass of cells) → blastocyst with inner cell mass (will become fetus) sitting in fluid pocket called blastocoel; edge of blastocyst cells are trophoblast (become placenta); around blastocyst is zone pellucida which blastocyst will hatch out of

Draw and describe parts of the blastocyst

Embryonic development 6 stages - real life

What is pregnancy recognition?

Sign that varies among species that will prevent PGF2a production so preg will continue

What is each species preg recognition signal?

Placenta 4 functions?

Protection

Nutrition

Respiration

Hormone production

Types of placentas and animals?

Diffuse: horse, pig

Zonary: dog, cat

Cotyledonary: sheep/goat, cow

Discoid: primate, mouse, human

Animal species broad names

Horse: equine

Cow: bovine

Pig: swine

Sheep: ovine

Goat: caprine

Cotyledonary placenta features

Placentomes covering the chorion made up of cotyledon (fetal) and caruncle (maternal)

-Blood supply goes through these and they’re attached to endometrium

Non-invasive

Epithelio-chorial: 6 layers of tissue between fetal and maternal blood supply

Cows (convex) and sheep (concave)

Explain convex and concave placentomes

Epithelio-chorial layers

Diffuse placenta features

Velcros to maternal side of placenta (endometrium) with chorionic villi (where blood crosses over in pigs)

Entire surface of chorioallantois attached to endometrium

• Chorionic villi = where blood crosses over in pigs

• Horses have microcotelydans instead of chorionic villi, this is still where blood crosses over

Rugae: maternal side of placenta in pigs

Areola: fetal side of placenta in pigs

Epithelio-chorial: 6 layers of tissue between fetal and maternal blood supply

Pigs and horse

Zonary placenta features

Central belt/girdle contains blood vessels and attached to endometrium

-Only place where blood can cross over

Endothelio-chorial: 4 layers of tissue between fetal and maternal blood supply

Cats and dogs

Endothelio-chorial layers

Discoid placenta features

Disc shaped placenta containing chorionic villi attached to maternal endometrium

Most invasive b/c burrows into maternal endometrium

Blood can only be transferred where the disc is, the placenta creates a large pocket of blood that the disc will float in

-All nutrients go through the disc, then through the umbilical cord, and into the fetus

Hemochorial: 3 layers of tissue between fetal and maternal blood supply

Humans and rodents

Hemochorial layers

Which placenta is most and least efficient?

Most: discoid b/c fewer layers (3) for blood from mother to fetus to pass through

Least: cotyledonary or diffuse b/c more layers (6) nutrients have to travel between from mother to fetus

How do we estimate fetal age? Give cow age by animal sizes

Pigs and cows: crown-rump length

Cows: rectal palpation or ultrasound

-2 months: mouse

-3 months: rat

-4 months: small cat

-5 months: large cat

-6 months: medium (Beagle) sized dog

What is used to estimate fetal age for crown-rump length? Talk about rate of growth

Logarithmic chart

Fetal growth is slow in first 2/3 of gestation; grows quickly in last 1/3

-Energy requirement increases during last 1/3

Gestation durations? (7 species)

Elephants – 616 days (2 years)

Mare – 340 days (11 months)

Human – 284 days (9 months)

Cow – 282 days (9 months)

Ewe, Doe – 150 days (5 months)

Sow – 114 days (3 months, 3 weeks, 3 days)

Mice – 21 days – FAST!

Label

A: Morula

B: Blastocyst

C: Inner Cell Mass (becomes fetus)

D: Trophectoderm (becomes fetal portion of placenta)

E: Blastocoele

What does crown-rump length suggest about energy requirements during gestation?

Low requirement prior to attachment and high energy needed during exponential growth phase in last 1/3 of gestation

Mammary Gland

How many glands on dairy cow and how many teats? Can milk pass between glands?

4 separate glands each with one teat

Milk that has been synthesized in one gland can't pass over into any other glands

How much does udder weigh?

100 lbs

Two ligaments?

Median suspensory ligament: divides the udder into right and left halves, and is located along the center of the udder, it can stretch as the gland fills with milk

Lateral suspensory ligament: acts as the "sling" around the udder, it provides support for the udder and doesn't stretch as the gland fills with milk

Milk is produced from what? How many alveoli per mammary gland?

Milk will be produced in epithelial cells that are grouped together in tiny storage units called alveoli are sac-like structures

Each mammary gland has millions of alveoli

Where does milk from alveoli go?

Empties into ducts which empty into larger ducts until eventually reaching the gland cistern

What is the gland cistern? Size? Location? Separated from teat cistern by what? What happens during milk letdown?

Largest storage area for milk

Located above the teat cistern at the base of the udder, it is separated from the teat cistern by the annular or cricoid fold

Gland cistern will fill rapidly during milk letdown

What is inside each teat? How much does it hold?

Inside each teat is a cavity called the teat cistern

Holds 0.5 to 1.5 ounces of milk

This is where milk will accumulate before being removed through the teat end during milking

Continuously refills during milking

What is located at the end of the teat? Size? Held together by what? Two functions?

Streak canal

1/4 to 1/2 inch in length

The streak canal is held closed by sphincter muscles

Functions:

1. To prevent the escape of milk between milkings

2. To act as a barrier to the entry of bacteria

Hormones related to milk

Prolactin: Promotes milk production

Oxytocin: Stimulates milk letdown

Catecholamines (Epinephrine and norepinephrine): inhibits milk letdown

Milk letdown response pathway

Teat stimulation → nerve impulse from the mammary gland via the spinal cord to the hypothalamus → oxytocin released from PP into blood → myoepithelial cells in mammary gland contract → force milk out of alveoli into lacteriferious ducts into gland cistern into teat cistern then out

How often are dairy cows milked per day? NCSU? What does more frequent milk removal do?

Most farms milk 2-3 times per day

NCSU Dairy Unit 2 times per day

More frequent milk removal can increase milk yield

Why is milking schedule important

Cows should follow a consistent milking schedule to minimize stress and maximize milk production

Milking process steps

Teats wiped with paper towel to remove loose soil → pre-dip solution on teats for at least 30 seconds then wiped off → hand milked quickly to open streak canal → attach milking machine that work with vacuum action (don’t undermilk or overmilk a cow so machines with an automatic take-off are an idea) → once the flow of milk drops below the threshold, usually 1.5-2.2 pounds, the milk claw will automatically detach → post-dip (iodine) to prevent mammary infections (most important part of mastitis prevention)

Label

A: Alveoli

B: Annular ring/annular fold/cricoid fold

C: Gland cistern

D: Teat cistern

E: Streak canal

Where is milk produced and stored?

Alveoli and gland cistern

Sows Parturition and Ultrasounding

Sow gestation length

Sows have an average gestation length of 112-114 days

Sow placenta type

Diffuse

Classification of piglets that die

Stillborn: die after day 100, or during farrowing

-Pre-partem stillborn: die before birth process (usually due to stress) (smaller/less vascular umbilical cord b/c not being used)

-Post-partem stillborn: die during birth process (usually due to dystocia)

Mummies: die in utero between day 45/50 and 90/100

-Partially reabsorbed by sow

-If all mummies are same size: acute stress event (vaccine?)

-If mummies vary in size: chronic stress (heat?)

Low viability: die after birth (usually runt)

NCSU Swine Unit Farrowing Schedule. How long do sows spend in farrowing room? When do they go into it and leave?

Week 1 - Wash sows and move into farrowing room prior to farrowing

Week 2 - Sows farrow and process piglets

Week 3 - Castrate piglets

Week 4 - Weaning

Based on this schedule, a sow spends about 1 month in the farrowing room, 1 week prior to farrowing and 21 days for lactation

How many gilts and sows will NCSU Swine Unit farrow in every group and how often?

Will farrow 50 gilts and sows in every group

They farrow one group a month

What is used to induce farrowing? Instead of what and why? When do they farrow after it? What is important to make sure about gestation date and it?

Lutalyse (PGF2a) is used instead of Oxytocin b/c the CL is responsible for maintaining pregnancy in sows; therefore, to induce farrowing we want to lyse all the CLs

Farrow within 24-30 hours after given Lutalyse

Make sure sows are as close to 114 days as possible before giving Lutalyse b/c giving Lutalyse too early can shorten the gestation length and cause a high incidence of stillborns

Signs prior to parturition (7)

Restlessness/nervousness/nesting (begins 24-48 hours prior to farrowing)

Refusal to eat (24 hours prior)

Milk present in nipples (12-24 hours prior)

Laying on her side, heavy "sighing" noises (12-18 hours prior)

Increased respiration rate (begins12 hours prior to farrowing and continues throughout labor)

Kicking or pawing at air while the sow is laying on her side (begins 4 hours prior and will precede birth of each piglet (sign of uterine contractions))

Bloody fluid will drain from the vulva (immediately before birth of a piglet)

When do most pre-weaning losses occur?

Most preweaning losses occur within the first 2 days of birth

When do we anticipate a new piglet

Every 15-20 minutes

Longer means we risk losing piglets to hypoxia in birth canal

What may be necessary if a sow is struggling?

To sleeve her and help remove piglets

Oxytocin may be used to increase uterine contractions

When are piglets weaned

21 days

Where are sows moved next and when do we expect them to come into estrous

Breeding barn

3-5 days post weaning

3 ways to pregnancy check

1. Detection of estrus with a boar

2. Progesterone concentrations 17-20 days after breeding

3. Use of ultrasound machines at day 35 and 56 after breeding

What does estrous with boar involve? What timeline is it done on?

21 day intervals

Simple and quick

Boar walks down aisle in front of sows

-If sow is in estrus and not preg she will exhibit sexual receptivity signs and that means she will need to be rebred

What does determining progesterone concentrations involve?

Effective but expensive

Catching and bleeding animals so labor intensive

Stressful on animals during critical embryo survival time

Preg animals will have higher P4 concentrations than non-preg 17-21 days after breeding

Using ultrasound

Initial investment is expensive

Reliable

Ultrasound for the first time at day 35 (first pregnancy recognition signal) and at day 56 as this is 21 days after day 35 (average estrous cycle length is 21 days)

What culling policy does the NCSU swine unit have

3 chances to get pregnant - if not they are culled

What do you have to be careful with when ultrasounding?

You’re checking for a fluid filled cavity so be careful as a full bladder can give a false positive reading

What does NCSU use vs other farms

At NCSU, the ultrasound machine uses sound waves that are sent out from and then return to a probe then these messages are turned into a visual picture of the reproductive tract

Some farms may use a doppler machine which can detect pregnancy even earlier (around days 25-35)

How accurate is ultrasound?

Very experienced technician using real-time ultrasonography will be accurate around 90% of the time

How to read ultrasound

Hollow organs: dark circles

Solid tissue (bone): will show up as white or gray streaks; will be a very bright object

Bladder: very large, dark, fluid filled object

Follicles: smaller, dark, fluid filled circles

Nonpregnant: dense gray circles that look like a doughnut if the sow is open, it will be very bright and have no fluid pockets

Pregnant: smaller dark fluid filled circles (fetuses)

Dystocia presentation types

Parturition Preparatory Stage 1

Uterine contractions

Rotation of fetus

Dilation of cervix

Fetal Expulsion Stage 2

Chorioallantois ruptures

-Water breaking

-Lubrication

Fetus forced through birth canal

-Abdominal and uterine contractions

-Remains in amnion

Rupture of amnion

Delivery of fetus

Umbilical cord severed

Delivery of Membranes Stage 3

Chorionic villi loosen and detach

Afterbirth is shed

Retained placentas (especially in ruminants)

-Early delivery

-Disease or vitamin/mineral imbalances

-Twins/triplets

-Can lead to hemorrhage, infection/sepsis

Pregnancy Diagnosis in Ruminants

Ruminant Gestation Length

282 - 284 days (9 months)

Most common preg diagnosis method in cattle?

Rectal palpation

How to perform rectal palpation? Equipment? What is the first thing you feel?

Shoulder length sleeve covered with lubricant (dispose of between cows)

Slowly insert arm into rectum and the first thing you will feel is the pelvic ridge

Pelvis is an excellent landmark for the palpator as it can help determine orientation and location

Then feel for a fetus

How early can preg be detected? And how?

An very experienced palpator can detect pregnancy as early as 28-30 days in cattle by feeling for the either the amniotic vesicle, the fetal membrane slip, or the fetus in the uterus

Advantage and disadvantage of doing preg check so early?

Advantage: identify non-pregnant cattle sooner and go ahead and rebreed them

Disadvantage: can accidentally cause the slipping of the amniotic vesicle which can disturb the implantation, resulting in pregnancy loss

Why do we palpate through rectum instead of vagina

We can rupture the cervical plug allowing bacteria and pathogens to enter the uterine body which can cause termination of the pregnancy

What does ruminant blood preg test check for

Presence of Pregnancy Specific Protein B (or PSPB) produced by the binucleated cells of the trophectoderm

Cattle gestation length

282-284 days

Semen Evaluation, Capacitation, and Body Condition Scoring

Which species has the easiest semen to preserve?

Cattle, especially dairy cattle, are the leading species where AI is used so a lot of research has been focusing on preserving cattle semen

What percent of each species use AI

Turkeys: 100% (all fresh)

Dairy cattle: 95%

Swine: 80% (mostly fresh)

Horses and Beef Cattle: 5%

Chickens: 0%