17a: Cow Infertility & Abortions

T/F: Anestrus is usually pathologic

False, usually physiologic

Causes of physiologic anestrus

• Pregnancy

• High producing diary cow

• Silent estrus

• Postpartum anestrus

Silent estrus is a significant management concern for what type of production

Dairy

Cause of silent estrus in dairy cows

There are no bulls running around, so producers need something other than overt behavior to detect estrus

Positive signs of pregnancy in a cow

• Amniotic vesicle

• Membrane slip

• Fetal ballottement

• Placentomes

When are we most accurate in staging pregnancy and estimating breeding date

First trimester of gestation

Why is is useful to be able to stage pregnancy

To tell a producer when to expect calving if they don’t have the breeding date

If a cow is later in gestation what do we try to use to predict parturition date

Fetal head size

Blood/milk progesterone findings consistent with a cow that is open after being bred

Low P₄ 20-24 days post breeding

T/F: if progesterone is high post breeding, the cow is pregnant

False, high P₄ is not always caused by pregnancy

Causes of high P₄ that may result in a “false positive” determination of pregnancy

• Ovarian abnormalities

• Pyometra

• Poor estrus detection

Source of pregnancy specific protein B (PsP)

Embryonic trophoblastic cells

When can we detect PsP

>30 days post breeding

When might PsP be falsely positive

After parturition or for a while after early embryonic death

How long can we ultrasound the whole fetus on rectal US

Up to 60-70 days

When can we sex a fetus on US

60-70 days

US finding that we use to sex a fetus

Genital tubercle just caudal to the umbilical cord (male) or below the tail (female)

When do we wean calves in dairy production

Immediately

Physiologic consequence of weaning dairy calves immediately

Dams don’t cycle back as well

What happens to dairy cow BCS as lactation increases

BCS drops off with peak lactation because feed intake doesn’t keep up

Typical calving interval for high producing dairy cows

15-18 mos

Length of voluntary waiting period

45-60 days

What determines the length of voluntary waiting period in cows

Uterine and cervical involution

How does lactation affect standing estrus

Standing estrus gets shorter as milk production is higher

How does the dairy industry compensate for standing estrus being so short

Timed AI

T/F: dairy producers can effectively manage herd reproduction by checking for estrus once a day

NO

Average rate of return to cycling for lower producing dairy cows

3 weeks

Why do 90% of dairy cows not show behavioral estrus after parturition

There is no P₄ priming of the hypothalamus for E₂ to produce strong behavioral signs

At what point after parturition do we get concerned that anestrus is pathologic and not physiologic

2-3 mos post parturition

Best time to check for estrus in a cow

During overnight, cold times of the day, or when they aren’t doing anything (not during feeding or milking!)

Diagnostics for silent estrus

Repeat physical exam and US

CS of standing estrus

• Stands for mounting

• Clear vaginal discharge

• Vulvar edema

• Vaginal hyperemia

• Increased uterine tone

Options for heat detection aids

• Chalk

• Electric/radio signals

• Altered or sterile bulls

Types of prostaglandin products

• Dinoprost (lutalyse): natural

• Cloprostenol (estrumate): synthetic

Prostaglandin product that is shorter acting

Dinoprost (lutalyse → natural prostaglandin)

If you give a prostaglandin to a cow what do you need to communicate with the producer

When to expect the cow to come into estrus

Timed AI protocol

1. CIDR

2. Prostaglandins when CIDR is removed

3. GnRH at breeding to ensure ovulation

Once a cow has a mature CL, what determines how fast she will come into estrus

Whether she has a dominant follicle (2-3 days) or not (4-6 days)

Prostaglandin protocol that can be used to synchronize a herd

Give 2 injections of prostaglandin 2 weeks apart and check for estrus on days 16-20

Why does 2 shots of prostaglandin work better than 1 shot of prostaglandin for herd sync

On a given day 60% of cows will have a mature CL in a herd, but at the second shot 80-90% will have a mature CL