Controlled "programmed" breeding

Question 1

Methods of estrus control

Answer 1

Estrous synchronization
Fixed timed breeding

Question 2

Estrous synchronization

Answer 2

Designed to bring cows into heat

Cows are bred as they are detected in estrus

Question 3

Fixed timed breeding

Answer 3

Designed to induce ovulation

Cows are inseminated at specific time without heat detection

Question 4

Common programs for estrus control in dairy cattle

Answer 4

Standard PG Program

Progesterone
* Intravaginal progesterone
* Oral Progesterone

Synchronizing ovulation
* Ovsynch
* Presynch - Ovsynch

Question 5

Prostaglandin (PGF2α) Protocol

Answer 5

PG causes regression of CL allowing the dominant follicle to complete development, produce estrogen, then cows come into heat and ovulate

Question 6

Prostaglandin (PGF2α) Protocol Option 1

Answer 6

Day 0 → PGF2α
Day 14 → PGF2α

2 – 6 days
Estrus detection & AI, or double fixed-time AI (72 and 96 h), or a single fixed-time AI (84 h)

Question 7

Prostaglandin (PGF2α) Protocol Option 2

Answer 7

Day 0 → PGF2α
2 – 6 days → Estrus detection & AI
Day 14 → PGF2α

2 – 6 days
Estrus detection & AI, or double fixed-time AI (72 and 96 h), or a single fixed-time AI (84 h)

Question 8

Progesterone (P4) Protocols

Answer 8

Exogenous progesterone act as artificial CL i.e. , they produce negative feedback effects on the anterior pituitary; which suppress cyclical activity by inhibiting the release of gonadotrophin

When the supply of the exogenous progesterone removed, the inhibition disappears and cyclical activity-resumes

Question 9

Progesterone (P4) Protocols types

Answer 9

Intravaginal Progesterone
Oral Progesterone

Question 10

Intravaginal Progesterone

Answer 10

Most common method
PRID - CIDR

Question 11

Oral Progesterone

Answer 11

Feed additive used in feedlot heifer
Melengesterol Acetate, MGA

Question 12

Intravaginal Progesterone dates

Answer 12

Day 0 → Insert device
Day 6 → Inject PGF2α
Day 7 → Remove device

Estrus detection & AI or, double (48 h, 72 h) or single fixed-time Al (56 h) after device removal

Question 13

Oral Progesterone dates

Answer 13

Day 0 to 14 → Feed MGA .5 mg
Sub fertile heat (16&20 days)
Day 19 → Discontinue MGA (Waiting period)
Day 33 → Inject PGF2α

HD & AI

Question 14

Intravaginal Progesterone devices

Answer 14

PRID :
Progesterone-Releasing Intravaginal device
Continually

CIDR :
Controlled Internal Drug Release
Like “V” shape

Question 15

Synchronizing ovulation (Ovsynch or GPG)
(GnRH - PGF2α - GnRH )

Answer 15

Day 0 → GnRH → Ovulation , Start a new Follicle wave

Day 7 → PGF2α → Regress CL

Day 9 (56–60 h) → GnRH → Ovulate follicle after 28 ± 4 h

Day 10 (16-24 h)→ Single fixed time insemination

Question 16

It is the today`s typical program for dairy herds

Answer 16

Presynch - Ovsynch program

Question 17

Presynch - Ovsynch program

Answer 17

Day (40) and Day (54) after calving → PGF2α → VWP → PGF2α injection accelerates uterus healing (14 day )

Day 0 (66) d after calving → GnRH → Ovulation , start a new Follicle wave

Day 7 → PGF2α → Regress CL

Day 9 (56–60 h) → GnRH → Ovulate follicle after 28 ± 4 h

Day 10 (16-24 h) → Single fixed time insemination

Question 18

Ovsynch program Advantages

Answer 18

1. No need for HD
2. Manages silent ovulation “problem cows
3. May cause anestrous cows to initiate cyclicity
4. Effective for treating follicular cysts

Question 19

Ovsynch program Disadvantages

Answer 19

1. The CR is lower compared to AI after detect estrus
2. Less effective in heifers
3. Costly

Question 20

PGF2a
Option 1 VS Option 2

Answer 20

Option 1:
HD after 2nd injection

Option 2 :
HD after 1st injection
Not detected cows injected again