Large animal reproduction

What type of estrous cycle do cows have

Polyestrous

Average length of cows estrous cycle

21 days

Onset of puberty in cows

10-12 months

Length of proestrus in cows

1-2 days

Length of estrus in cows

1-2 days

When do cows begin to ovulate

Within 24 hrs of the beginning of estrus

When does sperm need to be in the female cows

6 hrs before they ovulate

Length of metestrus in cows

1-3 days

What is seen during metestrus in cows

Mucous discharge with some blood

Length of diestrus in cows

4-18 days

Length of anestrus in cows

Zero days, they do not undergo anestrus

When can you breed a cow after parturition

On the 2nd heat cycle so the body can recover

Signs of heat in cows

• Decreased milk production

• Mounting behaviour

• Difficult to separate from herd

• May head butt or raise tail

• +/- vulvar swelling & clear mucous discharge

Signs a cow is past heat

• Will no longer stand to be mounted

• May still be mounting other cows

• Blood in vaginal mucous

Why do we synchronize cows estrous cycles

So calving season is all at once, easier of the producer

Prostaglandin products used to synchronize cows cycles

• Lutalyse

• Estimate

• EstroPLAN

Progestin products used to synchronize cows cycles

• Eazi-Breed CIDR

• MGA

Types of GnRH for cows

• Cystorelin

• Factrel

• Fertagyl

2 causes of reproductive failure in cows

• Failure in estrous cycle

• Failure in conception

2 causes of estrous cycle failure in cows

• Pathological anestrus

• Atypical estrus

Pathological anestrus in cows

• Nutrition - too little or too much copper

• Stress - changes in environment

• Uterine or ovarian abnormalities

Atypical esturs in cows

• Persistent CL

• Cystic ovaries

What causes failure of conception in cows

• Male reproductive issues

• STI’s

• Metritis/endometritis

• Freemartinism - 2 calves of opposite sexes

Length of cows gestation

9 months

What type of placenta do cows have

Cotyledonary

Pregnancy diagnostics in cows

• Cessation of estrus

• Ultrasound - 21 days

• Progesterone - 21-24 days

• PSPB - 29 days

• Rectal palpation - 35 days

• Abdominal enlargement, fetal movement, ballottement - 3rd trimester

• Mammary development late - 3rd trimester

Problems during gestation for cows

Early embryonic death & abortion

Causes of early embryonic death & abortion in cows

• Lack of nutrition to dam

• Toxins

• Congenital defects

• Viral or bacterial infections

Signs of impending calving

• Prominent & swollen vulva, +/- clear discharge

• Milk drip

Stage 1 parturition cows

Cervical dilation & uterine contractions

• 6-24 hrs

• Cervical relaxation

• Uterine contractions

• Ferguson reflex

Stage 2 parturition cows

Delivery of fetus

• 2-12 hrs

• Rupture of chorioallantoic membrane

• Release of oxytocin & PGF2 Alpha

• Abdominal contractions

• Fetus is delivered

Stage 3 parturition cows

• Approx. 3 days to weeks

• Placenta is passed

• Uterus returns to normal

What is dystocia in cows

Prolongation of stage 2 parturition

Causes of dystocia in cows

• Fetal size

• Fetal position

• Dam’s pelvis size

• Uterine inertia

• Uterine torsion

Tx for dystocia in cows

• Correct fetal position

• Calving chains

• Calving jack

Postpartum issues in cows

• Milk fever

• Prolapsed vagina

• Prolapsed uterus

Tx for milk fever

IV calcium

What causes a prolapsed vagina

Due to stretched ligaments

What causes a prolapsed uterus

Due to severely stretched or broken ligaments

Equine estrous cycle

Seasonally polyestrous

Average length of equine estrous cycle

21 days

Onset of puberty in horses

12-24 months

What 2 cycle stages do horses NOT go through

Proestrus and metestrus

Estrus in horses

• Average 5 days

• See signs of heat

• Ovulation 24-48 hours

Ovarian differences in horses

• Covered by a Tunica Albuginea

• Ovarian Fossa

How long is diestrus in horses

Average of 16 days

When is anestrus in horses

Late fall/winter

When can you breed a horse after parturition

On their 2nd heat cycle

What is the time for best heat cycles in horses

May - June

What is the best way to breed horses out of season

AI & physical manipulation

Does light & temperature have an effect on equine reproductive behaviour

Yes, better heat cycle when increase length of daylight

Influences on equine reproduction

• Breed associations age requirements

• Human-imposed breeding season

What does breed associations age requirements involve in horses

• Designated January 1st birthday for all horses born in a given year

• Pressure to have foals born early in season (Jan or Feb)

What does human-imposed breeding season involve in horses

• February 1st through July 15th in many breeds

• Lighting and hormones used to manipulate cycling

How do you detect heat in horses

• Works best with a teaser stallion

• Bring stallion within close proximity to mare

• Separate with a fence

Behavioural signs of heat in horses

• +/- clear mucous discharge

• Excitable around stallion

• Sawhorse stance

• Will elevate tail and hold aside

• Urinate in presence of stallion

• Vulvar “wink” after urination

What will you see on a visual exam for heat detection in horses

Not in heat = cervix is closed, small and pale

In heat = cervix is red and swollen

What will you feel on rectal palpation of the ovaries for heat detection in horses

Feeling for the follicle on the ovary

What will you see on ultrasound of the ovaries for heat detection in horses

They will be tear drop shape

3 causes of reproductive failure in horses

• Failure in the estrous cycle

• Atypical estrus

• Failure of conception

What causes failure in the estrous cycle in horses

Pathological anestrus due to nutrition, stress and age

What causes an atypical estrus in horses

• Persistent CL

• Split heats

What is a split heat in horses

When a young animal show signs of heat and then all signs abruptly stop for 24-48 hrs, after that signs of heat return

What causes failure conception in horses

• Male reproductive issues

• Endometritis

• Urine pooling

• Pneumovagina

Length of gestation in horses

11 months

What type of placenta do horses have

Diffuse

Pregnancy diagnostic techniques

• Cessation of estrus

• Ultrasound 14-15 days

• Progesterone 18-20 days

• Estrogen/estrone sulfate 100 days-2 weeks before term

• eCG 18-20 days (equine coriont genaditropin)

• Rectal palpation 20-60 days

4 diagnostic techniques that can be visualized in the 3rd trimester

• Abdominal enlargement and weight gain

• Fetal movement

• Ballottement

• Mammary development (late 3rd trimester)

3 problems during gestation in horses

• Early embryonic death (no calcified skeletal formation)

• Abortion (calcified skeleton)

• Twinning

What are causes of early embryonic death/abortion

• Lack of nutrition to dam

• Toxins

• Breeding on the foal heat

• Acute endometritis

Why is twinning a problem in horses

Their diffuse placenta type is not designed to house 2 foals, very rare they will both survive, one usual dies after birth or is born dead

3 signs of impending foaling

• Relaxed and elongated vulva +/- clear discharge

• Increased or decreased appetite

• Raised tail head

Stage 1 parturition in horses

Cervical dilation and uterine contractions

• 1-3 hours

• Cervical relaxation

• Uterine contractions

Stage 2 parturition in horses

Delivery of fetus

• <70 mins, very short

• Strong abdominal contractions

• Fetus is delivered

Stage 3 parturition in horses

Expulsion of placenta and involution of the uterus

• Placenta is passed within 1-3 hours

• Uterus returns to normal in 2-3 weeks

• Make sure they pass the full placenta!! Horses do not do well with a retained placenta, EMERGENCY

Is dystocia common in horses

No, if stage 2 is progressing longer than 30mins, monitor closely for signs of distress

Signs of dystocia in horses

• No significant progress within 10-15mins after the membranes rupture

• Premature rupture of the chorioallantois, known as “Red Bag Delivery” (acute emergency, foal is not get O2)

What is the biggest postpartum foal issue in horses

Constipation! All foals are prone

What causes constipation in foals

Failure to pass meconium (should pass within 4-12 hrs of birth)

Pigs estrous cycle (Porcine)

Average 21 days

What is unique about a pigs cervix and where is sperm deposited

• It is corkscrew shaped

• Sperm is deposited part way up the cervix

When does puberty occur in gilts (young pigs) and what stimulates it

4.5-6 months, stimulated by close proximity to a boar

Length of estrus in pigs

Average 2 days

Time of ovulation in pigs

40 hrs from the start of estrus

Best time for breeding pigs

12-30 hrs after signs of estrus begin

How often should you breed a pig if using AI

Twice, 12 hrs apart

Length of diestrus in pigs

Average 18 days

Length of anestrus in pigs

Zero, they do not undergo this!

Signs of heat in pigs

• Physical changes

• Behaviour changes

• Swollen, mucous discharge

• Mounting behaviour

• Decreased appetite

How can you make heat detection in pigs easier

Let the sows hear and smell the boars

2 benefits to AI in pigs

• Can breed more sows effectively

• Can bring in different genetics

What causes failure in the estrous cycle in pigs

Pathological anestrus: nutrition, stress

What causes failure of conception in pigs

• Male reproductive issues

• Very rare in sows

Gestation length in pigs

114 days

What type of placenta do pigs have

Diffuse

Average amount of litters a pig has a year

2.4 litters

Average litter size for pigs

10-12 piglets born

Average weaned litter size for pigs

8-10 piglets survive to be weaned

3 things that cause loss of litter size

• Early embryonic death

• Fetal mummification

• Stillbirth

Early embryonic death in pigs

• Occurs in first 6 weeks of gestation

• Affected embryos are reabsorbed

• Producer sees smaller than expected litter size