Timed AI

What is the primary benefit of Timed AI (TAI) programs in cattle reproduction?

An increased insemination rate (IR).

How does TAI impact the need for Estrus Detection (ED)?

It eliminates the need for ED because all cows have their cycles synchronized.

What is the average Pregnancy Rate (PR) for the standard Ovsynch protocol without optimization?

Approximately 30%.

At what specific stage of the estrous cycle should GnRH be administered to improve Ovsynch PR?

Early diestrus (days 5-9).

In the Ovsynch protocol, what is the physiological purpose of the first GnRH shot (GnRH 1)?

To induce ovulation of a pre-existing dominant follicle and the emergence of a new follicular wave.

Why is giving GnRH on days 1-4 of the cycle ineffective for synchronization?

There is no pre-existing dominant follicle available to ovulate.

What is the issue with administering GnRH on days 10-16 of the cycle during Ovsynch?

The first silent follicular wave has died off and the next dominant follicle is still immature.

How does a GnRH shot given on days 17-21 of the cycle negatively impact pregnancy maintenance?

It suppresses the production of P4 (progesterone), which is necessary to maintain pregnancy.

In Ovsynch, what is the function of the PGF-2a injection?

To induce luteolysis of the Corpus Luteum (CL) created by the first GnRH shot.

What is the physiological role of the second GnRH shot (GnRH 2) in the Ovsynch protocol?

To induce ovulation of the dominant follicle that emerged after the first GnRH shot.

When is Artificial Insemination (AI) typically performed relative to the timing of induced ovulation?

AI is performed around the same time as ovulation.

What is the primary goal of the Presynch portion of a Presynch + Ovsynch program?

To move all cows into the same time frame so Ovsynch can begin during the optimal 5-9 day window.

The standard Presynch protocol consists of two shots of PGF-2a administered _____ days apart.

14

Why do some cows fail to respond to the first PGF-2a shot in a Presynch program?

They may not have a functional Corpus Luteum (CL) at that specific time.

How long after the second PGF-2a shot of Presynch do cows typically ovulate?

3-7 days.

In a Presynch + Ovsynch program, GnRH 1 is administered _____ days after the second PGF-2a shot.

12

What percentage of cows are expected to land in the optimal day 5-9 window for GnRH 1 following a Presynch protocol?

Approximately 70%.

Why are CIDR programs for beef cows and heifers typically shorter than those for dairy cows?

To minimize the number of veterinary visits, as vets work with these herds less regularly.

Lactating dairy herds usually implement Presynch + Ovsynch protocols as part of _____ management programs.

weekly

At what point in Days in Milk (DIM) is the first PGF-2a shot typically given in a dairy Presynch program?

40pm 3 DIM.

In a standard weekly Presynch + Ovsynch program, at what DIM is Timed AI usually performed?

78pm 3 DIM.

What is the typical range for the Voluntary Waiting Period (VWP) in dairy production?

50-70 days postpartum.

According to TAI protocols, what specific event defines the end of the Voluntary Waiting Period (VWP)?

Artificial Insemination (AI).

How does the timing of the PGF-2a shot in a '5d cosynch' protocol differ from standard Ovsynch?

The PGF-2a shot is given 5 days after GnRH 1 instead of 7 days.

Which specific group of cows responds better to a Presynch/5d cosynch protocol compared to standard Ovsynch?

Anovular cows.

What is the benefit of combining Estrus Detection (ED) with a 5d cosynch program for non-pregnant cows?

It ensures a 100% Insemination Rate (IR) by the end of the VWP (80 DIM).

Double Ovsynch

A protocol where a full Ovsynch cycle acts as a pre-synchronization step for a second Ovsynch cycle used for AI.

What is the recommended timeframe for the initial pregnancy check following Timed AI?

29-35 days post-AI.

If a cow is confirmed pregnant, when should the reconfirmation check occur to diagnose potential pregnancy loss?

30 days after the initial pregnancy check.

How often should non-pregnant cows be reinseminated in a systematic breeding program?

Every 30 days.

What are the three management options for a cow diagnosed as 'not pregnant'?

Culling, reinsemination at estrus, or re-synchronization and TAI.

Why is a CIDR often preferred over Presynch + Ovsynch for re-synchronizing non-pregnant cows?

It is more time-efficient than repeating the full Presynch + Ovsynch protocol.

Under what condition is the impact of a TAI program least evident on a farm?

When the farm already has a high Estrus Detection Rate (EDR).

Which postpartum AI attempt usually yields the highest Pregnancy Rate (PR)?

The 1st postpartum AI.

In terms of reproductive efficiency, what does a steeper downward slope on a 'survival curve' of non-pregnant cows represent?

Higher reproductive efficiency (fewer days open).

What is the primary management shift that allows for good reproductive efficiency in TAI programs?

Working with groups of cows rather than individuals.

What are the three main goals of reproductive management in dairy herds?

Increase 21d PR, reduce interval between pregnancies, and minimize variability in time from end of VWP to pregnancy.

If a farm has excellent management and high Estrus Detection (ED), what is the primary factor that can still be improved to increase PR?

The Insemination Rate (IR).

In the Ovsynch timeline, how many hours pass between the PGF-2a shot and the second GnRH shot?

56 hours.

In the Ovsynch timeline, how many hours pass between the second GnRH shot and Timed AI?

16 hours.