Swine Vet Center1608 South Minnesota Avenue

Box 269St. Peter, MN 56082

Pre-screening of stud boars for low fertility: What are the options?

Darwin L. Reicks, DVM

Swine Vet Center

St. Peter, MN

Background

• What has changed in boar studs over the last 15 years

– What were we doing in the late 90’s?

– How are we better today?

1998 Leman Conference“Quality Control in the Lab”

• Sanitation

– In the barn

– In the lab

– Do’s & don’ts

1998 Leman ConferenceLab processing

• Lab Processing

– Volume – calibration of equipment

– Concentration

• calibration of equipment

• how to control variation

• 3-4 billion / dose

1998 Leman Conference

• Ejaculate Assessment

– Motility

• pass / fail

• Cutoff of 70% normal

1998 Leman Conference

• Ejaculate Assessment

– Morphology

• 50-100 sperm counted on each ejaculate

• Cutoff of 70% normal

• Correct for abnormalities

1998 Leman Conference

• Acrosomal ridge evaluations

– Evaluated every 2 weeks

– Adjustment for sperm per dose

• Compensate for boars who have lower % normal

0

500

1000

1500

2000

2500

3000

3500

Fre

qu

en

cy

91-100 81-90 71-80 61-70 51-60 41-50 31-40 21-30 11=20 1=10

%NAR Range

% Normal Acrosomal Ridge

6207 Ejaculates

1998 Leman Conference

• Other tests

– Quantification of seminal Plasma Proteins

– Fluorescent Staining tests

– Computer assisted sperm analysis (CASA)

– ORT – Osmotic Resistance Test

1998 Leman Conference

• Other quality steps covered– Agglutination

– Contamination

– Dilution ratio / osmolarity

– Extending technique

– Dispensing technique

– Semen cooling technique

– Transportation and temperature stability

– Use of a reference lab

1998

• Pre-screening of boars for fertility

– If majority of first 10 ejaculates fail - cull

WHAT IS DIFFERENT TODAY FROM 1998?

WHAT IS DIFFERENT TODAY FROM 1998?

…NOT MUCH

Some things are better

• End Product Monitoring

– Real time monitoring through reference lab

• Every production day

• Quick intervention if problems

Sperm counts and variation

Genetic information

• Genetic information

– EBV’s updated regularly in stud

• Didn’t get EBV’s in 1998

• Thanks!

– Modeling and producer understanding better

Where do we go from here…

• Need to be able to get more sows bred from higher index boars

– Lower sperm per dose – below 2.5 billion

– Need to do more to evaluate boars to maintain fertility as we drop to lower sperm counts

Why haven’t we reduced sperm numbers?

Sperm number vs. total piglets born (p = 0.03)Reicks, Levis 1998

10.0

10.6

11.110.9

10.4

11.4

9.7

10.2

10.8 10.8

11.1

11.6

9.0

9.5

10.0

10.5

11.0

11.5

12.0

< 2.5 2.5-

2.99

3.00-

3.49

3.50-

3.99

4.00-

4.49

4.5+

Farm 1

Farm 2

What more can be done

• Single sire matings

– Dutch model

• Everything single sire

• Seamless integration with sow data

• Continuous and ongoing feedback

– Don’t have today in North America

What more can be done

• Single sire matings

– 50 or more matings per boar as they enter stud

– Conception rates at 30 days

– Farrowing rate and total born

Single sire matings

• Advantages

– REAL data – not lab data

– Gold standard for fertility evaluation

Single sire matings

• Challenges– Add ½ to 1 person to keep track of and package

single boar ejaculates• ~$30,000 labor for 300-400 boar stud

– Have to set a deadline – often one turn of isolation• 6-8 weeks

• Low producing boars – hard to get 50 matings

• Boar replacement deadlines

• Sub-fertile boars replaced?

Single sire matings

• Challenges

– Early results don’t always translate to long term result

Single sire matings

• Use of farrowing rate as a measure of fertility of boars – 1989 JAVMA– K. Clark, A. Schinckel, W. Singleton, M. Einstein, R.

Teclaw

– Whether FR of first 10, 20, 30, 40, or 50 predicted FR of subsequent services through 100• Maximal r2 was 11%

• “farrowing rate of initial services of boars (<50) cannot be used as a reliable estimate of subsequent services through 100 farrowings and, therefore, cannot be used as a management tool for culling subfertile boars to improve herd reproductive performance”

Single sire matings

• Challenges

– Processing ejaculates on young boars with 8-10 doses per collection

• More opportunity for contamination

• More motility checks for stud and farm

• May take 30-36 weeks – ½ way through life

Other technologies

• CASA motility– Dutch database – may be parameters

• More predictive if trained lab technician

• Fourier harmonic analysis – sperm nuclear shape• K. Willenburg

• Flow cytometry– SCSA – Evenson

– Cell membrane viability / acrosomes

– Ubiquitin

– Many others being looked at

Flow Cytometry

Guava

Flow cytometrySperm chromatin structure (SCSA – Evenson)

Sperm viability and acrosome status

• Assays: Membrane viability

– Fluorescent membrane impermeant dye (PI, red)

• Acrosome integrity

– FITC (green) coupled with

plant lectins (PNA)

Sperm viability and acrosome status

• Boar sperm membrane viability and acrosome assessment (PI/FITC-PNA)

Sperm membrane organization

• Merocyanine

What can we do now

• Study set up

– Use technologies available today

• Screen a population of boars

– Evaluate prescreened boars in second phase

• PCAI

• Conventional AI

Objectives

• Determine the effect of a complete post cervical artificial insemination (PCAI) system (with a 38 ml, 1.5 billion total sperm dose) on Farrowing Rate and Total Born when compared to conventional AI at 76 mls and 3.0 billion sperm per dose.

Materials and Methods

• 50 boars

• Extended to 2.75 billion

• Target 50 sows bred per boar

– Limit on time – 3 mo.

– Controlled by # ejaculates sent out

• PCAI portion during seasonal infertility period

– July - September

Materials and Methods

• Ejaculate screen at stud (50 sperm counted)

– >70% motility

– >70% normal morphology

– >70% normal acrosomes (on most recent eval.)

Materials and Methods

• Testing at reference lab

– Differential Morphology (200 cells)

– Motility (CASA Hamilton Thorne Ultimate)

– Sperm plasma membrane viability (flow cytometry Guava)

– Acrosome integrity (flow cytometry Guava)

– Meracyanine (flow cytometry Guava)

– Sperm chromatin structure assay SCSA (Evenson)

Boars to remove

• Test results

– If <70% in multiple parameters

– If <60% normal in any one parameter

• Conception Rate

– If <80% conception rate

Results – single sire matings

• Boars removed for conception and screening tests

– Had to make a call before all sows >30 days bred

Results

• Test results only

– 2 boars

• Test results and initial conception

– 3 boars

• Conception rate only

– 5 boars (4/5 borderline)

Was it the right boars?

• With all conception rate in through 50 days

– 5 / 8 still below 80%

– 3 / 8 now above 80%

– 2 others below 80%

• Not identified by any of the tests

Clear?

Clear?

• …

Need the numbers!Marsh & Soler 1993 AASV Journal

Farrowing Rate and Total Born

• Total Born

– No other problem boars identified (1/2 farrowed)

• Farrowing Rate

– Follows conception rates

Phase 2: PCAI

• Conventional (3.0 billion)

• PCAI (38 ml and 1.5 billion)

• 1000 sows per group

• 2 sow farms (2500 & 5000 sows)

PCAI study

• Conception rates (first half)

Group CountConception

Rate

C 565 90.1

P 442 81.4

U 5 80.0

Total 1012 86.3

Summary

• Need to be able to reduce sperm counts

– Increase genetic value

– PCAI can help us get there

– Implementation is not without risk of lower production

Summary

• Single sire matings

– Need to breed enough sows – at least 50 / boar

– If lower farrowing rates, need numbers

– Wait for farrowings to properly screen boars

• Need the total born information

• What to do in the mean time – use the boar?

Summary

• Normal morphology & motility screening on each ejaculate– Use boar history for culling

– Some have been doing this for 15 years

• Some exciting tests are available– RT

– Flow cytometry

– Others

– More coming – need more development

Summary

• With lower sperm counts need better quality

• No one test nor single sire matings is going to be the solution for a lifetime fertility screen

– Need combination of tools

– Need better tools developed

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