induction and synchronization of estrus in prepubertal gilts · induction and synchronization of...

Induction and Synchronization of Estrus in Prepubertal gilts

Dr. Rob Knox University of Illinois 1


Rob Knox

Department of Animal Sciences

University of Illinois,

Champaign-Urbana, IL USA 61801

Feb. 28th 2011

Puberty the real story

• Pubertal estrus – Can be hit or miss

– may be spread over >60 days

– Some never express puberty

– Variable symptoms of heat • (standing is strong or weak, vulval swelling)

Percent of 120 farms reporting problems with infertility in a 2007 sow survey (220,000 sows)

0 10 20 30 40 50 60

Sows bred within 7 days

Irregular returns

Regular returns

Gilt estrus

NIP

Irregular estrus intervals

Low born alive

No decline

Multiple matings

Abort

Stillborns

Mummies

% of farms

Rea

son

s



Maturation occurs over time but can be influenced by factors in proportions of gilts

0102030405060708090

100

50 75 100 125 150 175 200 225 250

Per

cen

t

Days of Age

Med Foll

LH Pulses

There are limited methods to induce estrus in swine within a week but techniques can be additive

ITEM INDUCTION RESPONSE

• Boar exposure 20-40%

• Relocation stress 5-10%

• Regroup stress 5-10%

• Hormones 50-90%

Age at Puberty in BreedsRange may be more appropriate

Breed (1951-2000)C. White 201-259P. China 198-216Yorkshire 199- 210-249Landrace 173Large White 211Hampshire 207Duroc 224PietranSynthetics/cross 200-225Meishan 90



Genetic Influence on ReproductionNPPC Maternal Line Project

Genetic % Age at 1st %

Line bf 1st estrus estrus farrowing

American diamond .79 91 225 77

Danbred USA .56 87 222 77

Dekalb Monsanto DK44 .70 87 222 75

Dekalb Monsanto MXP200 .71 97 209 92*

Natl. Swine Reg (Y x L) .66 90 222 77

Newsham Hybrids USA .58 88 223 78

Estrus detection: Moved from pens of 25 into crated 1600 sows facility at 180 d and exposed to a V boar 2/x /d

Moeller et al., JAS 2004 82: 41-53

-GROWTH RATE

Growth rate and pubertal estrus + BE at 140 d

Foxcroft, 2005 from Beltranena 1991

Select for >600 g/d

Gilt estrus is unique

• Females very sensitive and aware of humans– Perform routine to get them accustomed

– Allow more time and patience

– Be consistent in daily process

• May go off feed



To improve consistency

– Use record sheet to aid the process• Females can be tracked across cycles

• Patterns can be revealed

A record sheet example

i.d. day day day day day day

am pm am pm am pm am pm am pm am pm

Gilt 1 - - -R -R +R +R ++R ++R E E E -

Gilt 2 + + + - - -R - + + - -

Gilt 3 - - - - - - - - - + + +R

Gilt 4 + + + + +E + + + + + + +

Gilt 5 - - + + + +R +R +R E E - -

Vulval swelling scoresSwelling (none (-), some (+), evident (++)Red color (-R), (+R)

Boar Exposure Factors

• Choices– Pens or Stalls

• Move – Boar to gilts– Gilts to boar

• Physical vs. Fenceline• Frequency• Duration • Age to start



Number of gilts per day showing estrus after stimulation with direct boar contact from 160 d

From: Foxcroft, 2004

0102030405060708090

100

140 160 180 200 220 240 260

cum

mul

ativ

e es

tru

s (%

)

Days of age

140

160

190

210

What age to start boar exposure ?

How often to apply boar contact for puberty

0

10

20

30

40

50

60

Jan May Oct

day

s

Month at start of boar exposure

0 d / week

2 d/week

5 d / week

7 d/ week

Paterson et al., 1989; Anim. Reprod. Sci. 21:115-124



Dept. of Animal Sciences, University of Illinois

Watch for unintended boar exposure -Estrus Detection Test-

(3 min test)

3 ft Alley

Boar

Gilts

Opposite

BoarGilts

Adjacent

Boar

Gilts

Isolated

Tilbrook & Hemsworth, 1990

Duration of daily boar exposure on puberty

0

10

20

30

40

50

60

70

0 2 10 30

day

s

Minutes of exposure/day

Paterson et al., 1989; Anim. Reprod. Sci. 21:115-124

Effect of once or twice daily Boar exposure on Puberty

0

20

40

60

80

100

120

0 10 20 30 40

% e

stru

s

Days to estrus

1X

2X



Effect of Type of Boar Exposure On Accumulative Estrous Expression

Zimmerman et al., 1998

0

20

40

60

80

100

120

10 20 30 40 50 60 70 80

Cu

mm

ula

tive

Est

rus

(%)

Day of age

FBE-2x

FBE-1x

PBE-2x

PBE-1x

160 d exposure, 10 min/day

Effect of Transportation and Boar Exposure on Gilt Puberty

Control Transport 1X BE 1X BE + T

Pubertal 29% 0 25% 56%

AAP 186 - 179 187

Hughes et al, 2007 ARS 46:159-65

Percent of gilts pubertal and days to puberty in response to LIBIDO

No Boar Low Libido High Libido

Puberty 20 d 0 19 59

Puberty 40 d 8 62 81

Puberty 60 d 35 88 89

Days to Puberty 48 d 34 d 19 d

Hughes, 2001 VIth Intl. Conf. Pig Reprod. Pre-conf. Workshop.



Gilts/Pen

• If ratio of gilts to boar is >6:1 – time to expose may need to be >10 minutes

Hughes 2001 , Intl. Conf. Pig Reprod. Pre conf. workshop

HORMONAL INDUCTION OF PUBERTY IN GILTS

PG600

• Combination of eCG + hCG– 60-70% express estrus

– Estrus in 4-6 days

– Estrus lasts 1.5 days



Response of gilts by age to PG600

Field ExperienceOpportunity Gilts (n= 799) Receiving PG600170 d BE and if no estrus PG600 23 days later

0

10

20

30

40

50

60

1 2 3 4 5 6 7 8 9 10

Per

cen

tag

e

Days from PG600 to HNS

Sporke et al., 2005

Day 0. PG600 injected into muscle

PG600 diffuses into blood

Binds to follicleswith FSH and LH receptors

In 5 daysStimulates large follicle Growth, and Estrogen production

E EEE

EE

PG600



Effect of gilt development diets differing in amino acid to energy ratio on response to puberty induction in

replacement gilts at 175 d (weight at PG600)

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10 11 12 13

kg

Week

diet 1

d2

d3

112,000 g = 640 g/d97,000 g = 554 g /d

(100 days) (175 days)

Effect of diet on PG600 Puberty Induction

Diet 1 Diet 2 Diet 3 P

Estrus (%) 100 92 67 <0.05

Dur heat (h) 53.8 58.9 63.0 ns

OV (%) 91 100 83 ns

CL 21.6 23.3 36.5 ns

Effect of PG600 and No Daily Boar Contact or Daily Boar Contact on 1st and 2nd Estrus

NBE BE

1st estrus 49% 81%

1st Ovulation 84% 88%

2nd Estrus 76% 100%

Barlett et al., 2009. Anim. Reprod. Sci. 114:219-227.



Effect of adjacent boar housing on cyclic activity following hormone induction of

puberty in gilts

Boar No Boar

2nd estrus 87% (20/23) 52% (12/23)

2nd ovulation (18/23) (12/23)

Paterson and Lindsay, 1981 Anim. Prod. 32:51-54

WHAT DO WITH GILTS OF UNKNOWN STATUS?

Effect of PG600 on cyclic and non-cyclic gilts

• At older ages >210 d without heat

• Of 15 gilts not in known heat:

– 12 were cyclic and all cycled in 8-17 d with no problems

– 1 was silent heat gilt and cycled in 10 days

– 2 were prepubertal gilts and were in estrus in 5 days



Experiment 1. Frequency for estrus for all gilts following PG600 on ~d 10

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

%

Days following PG600

Prepubertal gilts (n=2)

Cyclic gilts (n=6)

Cyclic gilts(n=6)

Summary

• Choose and implement a outcome consistent boar exposure system

• Expect age differences for breed/farm systems

• Develop your gilts

• Use gilt records for heat

• Use hormones properly when you choose

Thank you for your attentionAny Question?

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