Breeding Programs/Systems-

Utilizing Natural Service and

Estrus Synchronization

Cameron Co. Master Rancher Program

Joe C. Paschal

Texas A&M AgriLife Extension

Corpus Christi, Texas

j-paschal@tamu.edu

Breeding Programs

• Natural Service– Requires bulls

• Buy, lease or borrow

– Purchase costs

– Maintenance costs

– Bull pastures or leave with cows

– Breeding soundness examination

– Breeding ratios

– Genetic value

– Salvage values

• Artificial Insemination– Requires semen

• Conventional or sexed

– Requires AI skills or technician

– Requires fewer bulls

– Breeding soundness examination

– Purchase costs (semen and bulls)

– High breeding ratio

– Genetic values

Combination Program

• Breed a percentage of (or all) heifers AI to

develop replacements, breed cows to

make sale calves.

• Use estrus synchronization or natural

heat.

Artificial Insemination

• Artificial insemination (AI) is

practiced primarily by

purebred breeders and then

by only a fraction of them

– Higher in some breeds

• EPD and bloodline

– Most will breed heifers or

better cows AI

• Some will breed all

– Club calf projects

• AM/PM Rule or Timed AI

(66 – 72 hrs)

Benefits of AI

• AI has several benefits– Can use the genetics of

superior bulls not available to you to produce replacements

– Reduce disease transmission

– Mate specific bulls to specific cows

– Improves your cattle nutrition and health management

– Reduces breeding/calving season

– Best if used with estrus synchronization

Drawbacks of AI• AI has several drawbacks

– Not every cow bred AI will conceive (50-70% will)

– Semen quality

– You must have good herd nutrition and management

– You must invest in training or custom hire experienced tech

• For AI

• For synchronization

• For heat detection

– Cost is involved• Equipment and drugs

• Labor

• Training or custom hire

• Increased nutrition and herd health

Technique

• Good AI technique

begins with a clean

space

• Equipment needs:

– Semen tank

– Straw thawer (96F)

– Plastic gloves

– Insemination gun

– Sheath

– Lube

• Skill and patience

What is Estrus Synchronization?

• Estrus

synchronization is

an attempt to

synchronize the

reproductive estrus

cycles of all the

selected cows and

heifers

What is the Estrus Cycle?

• The estrus cycle is the reproductive cycle of the cow

• Begins at ovulation and ends before at the next ovulation

• Controlled by hormones secreted from the brain and reproductive organ

• Averages 21 days

• Ranges from 18-23 days

The Estrous Cycle

0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 7 18 19 20 21

Estrogen

FSH, LH

Progesterone

EstradiolLH

FSH

Progesterone

Hormone Profile of Estrous Cycle

Luteolysin

Release

GNRH

Release

GNRH

Release

Ovulation

Ovarian Structures

Corpus luteum (CL)

Large follicle

Primary and

growing

follicles

Why Synchronize Estrus?

• Have more cows breeding and calving within a shorter period of time

• Increase efficiency of bull power

• Improve use of labor at calving

• Increase weaning weight and uniformity of calf crop

• Produce replacement heifers more likely to achieve puberty early

How Can Estrus Be

Synchronized?

• Estrus synchronization can be accomplished by two basic methods

– Two 5 cc injections of prostaglandin (PF2a) in the muscle 9 days apart

– Vaginal insertion of the EAZI BREED CIDR for 7 days and then a PF2a injection the day before or the day of removal

• Research has shown that the CIDR provides a more concise grouping of heat, important in timed AI breeding

What Does it Cost?

• Depending on the method chosen

– Two injections of prostaglandin (PF2a) 9 days

apart

• $5.00/hd

– Eazi Breed CIDR for 7 days and then 1

injection of PF2a

• $12.50/hd

How Does PF2a Work?

• Prostaglandin (PF2a)

– Prostaglandin eliminates the corpus luteum on the cows in the last 2/3 of their cycle (Day 7+)

– The second shot 9 days later eliminates the CL from the other 1/3 who grew a CL after ovulation (Day 7 or earlier)

– Ovulation and heat will occur within 48-96 hours

– A variation is to check heat for 5 days and then give PF2a only to those cows who have not shown heat

– Trade names: Lutalyse and Prostamate

– Inject IM in neck!

How Does the CIDR Work?

• EAZI BREED CIDR– A progesterone impregnated

device is inserted intravaginally. Progesterone will keep the cow from ovulating but allow follicles and corpus lutea to grow

– After 7 days, the CIDR is removed and a PF2a injection is given (or given the day before removal)

– Ovulation and heat will occur within 36 to 72 hours.

– May “jump start” heifers

– Inject Pf2A IM in the neck!

Comparison of Estrus Synchronization in Beefmaster Heifers With CIDR Removal and PF2A

on Same Day Vs. One Day Apart

12

4147

71

1218

0

10

20

30

40

50

60

70

80

Perc

en

t in

Heat

Same Day One Day Apart

Treatment

24 hrs

48 hrs

NIH

Comparison of First Service Conception vs Rebreeds in Beefmaster Heifers With CIDR

Removal and PF2A One Day Apart

82

18 18

33

0

10

20

30

40

50

60

70

80

90

Perc

en

t

First Rebreed

Treatment

In Heat

Not In Heat

Problems with Estrus

Synchronization

• Need good facilities, calm cattle, cycling cows in good BCS, labor, fertile bull power, synchronization products

• PF2a program is good for cows and cycling heifers but CIDR program might jump start heifers

• Don’t expect 100% (or even 75%) in estrus if you have Bos indicus cattle

• Immature heifers may not respond

You have to be there! For

AM/PM AI, the more you

check, the better your AI

conception rate will be!

Reproductive Tract Scores

Score Horns Ovaries Follicles Bred

w/ ES

Total

Bred

1 Immature

<20 mm

15x10x8mm None 2.6 26.2

2 20-25mm

no tone

18x12x10mm 8mm 22.6 74.2

3 20-25mm

some tone

22x15x10mm 8-10mm 39.5 76.2

4 30mm

good tone

30x16x12 >10mm

CL?

54.6 94.1

5 >30mm

good tone

>32x20x15 CL 55 85.0

Products Used in ES and AI• Prostaglandins (®Lutalyse, Prostamate, Estrumate)

• Produced by the uterus, regresses the CL

• Injection: cyclic females with a CL (days 7 to 16 of cycle) will respond and be in heat within 2 to 6 days (about 67%)

• Will cause abortion from 7 days - 5 months.

• Progesterone (CIDR, MGA)• Produced by the CL (and placenta), maintains the pregnancy

• Blocks estrus and ovulation during diestrus phase of cycle

• Use CIDR (intravaginal insert) or MGA (feed additive for heifers)

• Acts as an “artificial CL” to “hold” animals out of heat

• Their timed removal will cause heat (7 days +)

• CIDR + prostaglandin or GnRH may “induce” 20-40% anestrous females

• GnRH (® Cystorelin, Fertagyl, Factrel, Ovasync, OvaCyst)• Produced by the brain (hypothalamus)

• Causes other brain hormones to stimulate follicular growth and ovulation

• May “induce” 10-30% anestrous females

• Not recommended for prebubertal heifers

The “Easy Three”

• Heat check for 5 days and breed, on day 6

inject all other cows with PF2a and heat

check (AM/PM) or breed within 66-72 hrs

• Insert CIDR and remove 7 days later (on

day 6 or 7 give PF2a injection). Heat

check (AM/PM) or breed within 66-72 hrs

• Previous program but include GnRH 48 hr

after CIDR removal

Detecting Heat• Determining when a cow is

coming into heat requires a little knowledge, practice, time and luck– Cows coming into heat will

“bull” other cows, pushing and nudging and attempting to mount them

– A cow in heat will allow herself to be mounted, her vulva will be swollen and mucous may stream out and her tail head hair may be roughed up and she may have dirt on her flanks

– A cow going out of heat will not allow herself to be mounted

Methods (Aids) to Estrus

Detection

• There are aids to

estrus detection

– Visual inspection

– Chin ball marker on a

marker bull or cow

– Paint/chalk on the

cow’s tail head

– KMAR heat patch

– Estrus Alert patch

– Heat Watch system

Picture courtesy of Dr. Glen Selk

OSU Extension Facts No. 4154

KMAR Patch

Estrus Alert Patches

Will ES Pay in a

Natural Service Herd?

• Consider a 50 cow 2 bull herd– A 90 day (4 estrous cycles) breeding and calving

season

– Cows and heifers are cycling and in good BCS

– Bulls are fertile

– A 90% calf crop

– Calves gain at the rate of 1.5 lb/d

– ES programs cost $5.00 for PF2a (2X) and $12.50 for CIDR

– Only 2/3 (66%) of the cows respond to ES and are bred at that time, the rest breed later

Effect of ES on Calving

Distribution and Weaning WeightNon ES 1st 2nd 3rd 4th Total Difference

No.

calves

10 20 10 5 45

Weight 500 468 436 404 20740

ES 1st 2nd 3rd 4th

No.

calves

30 15 0 0 45

Weight 500 468 22020 1280

Costs and Returns from ES

Non ES ES Difference

Weight 20,740 22,020 1,280

Value $29,036 $30,828 $1,792

Costs Returns ROI

PF2a $0 $250 $1,542 1:4.4

CIDR $0 $625 $1,167 1:2.5

Timed AI Program Costs

• Semen $15.00 per cow

• Synchronization + GnRH $15.00 per cow

• AI Tech $5.00 per cow

• Labor $5.00 per cow

• Total $40.00 per cow

• A 50% pregnancy rate: $80.00/calf

• A 75% pregnancy rate: $60.00/calf

• This will be offset by older and heavier calves, better genetics, higher levels of reproduction in replacements

AM/PM AI Program Costs

• Semen $15.00 per cow

• Synchronization + GnRH $15.00 per cow

• Heat detection $1.50 per cow

• AI Tech $5.00 per cow

• Labor $10.00 per cow

• Total $46.50 per cow

• A 60% pregnancy rate: $77.5/calf

• A 80% pregnancy rate: $58.13/calf

• This will be offset by older and heavier calves, better genetics, higher levels of reproduction in replacements

Comments….

• Artificial insemination is not for everybody and

the point of this presentation was to outline the

procedures, potential benefits and possible

pitfalls. If you are interested check with your beef

cattle veterinarian or county extension agent.

• Estrus synchronization on the other hand could

be used successfully in all herds to shorten

calving seasons, produce a more uniform calf

crop (in age weight) and more productive

replacement females as a result.