Gilt Management/Puberty Induction and Sow Longevity/Productivity - Dr. Rob Knox, University of Illinois, from the 2012 Allen D. Leman Swine Conference, September 15-18, St. Paul, Minnesota, USA.

1. 2012 Leman Pre-Conference Reproduction Workshop
Rob Knox
Department of Animal Sciences
University of Illinois,
Champaign-Urbana, IL USA 61801

2. Premise of Gilt Development and Sow Longevity
• How we develop Gilts impacts their maturity/fertility
at mating and in subsequent parities
– Problems in development result in :
• >days to 1st service
• >non-productive days
• Reduced fertility
• >health problems
• higher fallout rate

3. -High culling rates-
an old problem?
– From 1960 to 2000 (NHF Review 2004)
• Culling rate No. of Studies
• 20-30% 9
• 30-40% 8
– PigCHAMP 2007 50.0%
– Koketsu 2007 JAS 85:1086-91 40.6%

4. Why a gilt won’t make it to parity 5
Puberty
delay
No puberty
Conception
failure Low litter
return to size
service
CULL Poor
Failure to condition
rebreed body
after weight, Fee
weaning t/legs, healt
Poor h
litters

5. The realities of Gilt Replacement
• Great variation in
– gilt growth/body development
– Days to pubertal estrus
– symptoms of standing and vulva swelling
• Some never express puberty
• Many are culled before their 1st, 2nd or 3rd litter

6. In prepubertal gilts, proportions of gilts
showing brain and ovary maturation by age
100
GnRH
90
80
70
Percent
60 Med Foll
50 LH Pulses
40
30
20
10
0
50 100 150 200 250
Days of Age

7. The Physiology of Gilt Puberty
• Ovaries/uterus can grow and respond by 120 d of age
• (Guo, et a., 1998 JAS 163-68)
• Hypothalamic-pituitary axis is fully mature in LH response to
estradiol feedback and external stimuli by 210 d (not 150 d).
• Barb et al., 2010 ARS 122:324-7
• Increased LH pulses increase all reproductive measures
• Estrogen, ovary and uterus weight ) Beltranena et al., 1993 JAS
71:471-80
• Maturity relies on
• Estrus behavior (symptoms/duration)
• Ovulation (rate and timing)
• Uterus Size (capacity)
• Cycle length and repeatability

8. Most but not all gilts express estrus by 260 d of age
Estrus in gilts following Boar Exposure at 180 days of Age.
30
25
Percentage
20
15
10
5
0
0 5 10 15 20 25 30 35 40 45 50 55 60 >60 none
Days
72.5% (n = 700/965) estrus in 80 days (AASV Pre Conf. Symp. Foxcroft, 2002)

9. Puberty Can be influenced by
Farm, Breed, Management
Hughes et al., 1990; J. Reprod. Fertil. Suppl. 40:323-341

10. Where Can Selection Pay Off for Gilt
Fertility?
AVG SD CV h2
AAP 210 26 12 0.32 *
Vulva symptoms 0.83 0.38 *
Standing response 0.87 0.29 *
Ovulation rate 14 3 19 0.24 *
ES 0.8 0.2 23 0.14
Born alive 10.3 3 29 0.10
WEI 7.7 6.9 90.1 0.10
• Merks et al., 2000 RDA 35:261-66

11. Selection of gilts for standing and Vulva symptoms at
pubertal estrus improves subsequent generations
Rydhmer et al., 1994 J. Anim. Sci. 72:1964-1970 (Yorkshire)

12. Gilt Selection for fertility
• In Mothers of Gilts
– Offspring of early puberty mothers (d 185) cycle earlier with more BF than
those selected for late puberty (d 235)
• Hixon et al., JAS 1987 64: 977-82
• In Litter size
– Gilts from large litters where uterine crowding occurred have smaller
placentas and smaller fetuses (h2 = 0.10).
• Van der waaij et al., 2010 JAS 88:2611-9
• Gilts
– low BF at early AAP (<d 185)
– Heavy birthweight in large litters (relative to herd)
– estrual score and early AAP
– Growth rate and BF at AAP

13. Higher Growth Rate Reduces AAP
• Higher growth rate (>600 g/d) to 140-165 d (r = -0.40) with AAP
• Tummaruk et al., 2009 ARS 110:108-22 (tropics)
• Foxcroft, 2005 from Beltranena 1991 (CAN)
Growth rate (g/d) n AAP with BE start Pubertal by 190 d
at 144 d
577 58 155 d 76%
724 58 164 d* 95%*
Kummer et al., 2009; Reprod. Dom. Anim. 44:255-9 *1.21 lb/d = 0.55 kg/d = 550 g/d
1.30 = 590 g/d
1.45 = 660 g/d
1.60 = 727 g/d

14. Feeding the developing gilt
• Energy intake in G-F changes growth, weight and BF not reproductive
measures
• (FF E2, plasma E2, repro tract wgt, or LH) Beltranena et al., 1993 JAS 71:471-80
• Feeding method has few effects on reproduction but reduces
weight variation at farrow
– Schneider eta al., JAS 2007 85:3462-9
• Weight gain from 161-171 d (500 vs. 1000 g/day)
• High increased medium follicles (25 vs. 34) and oocyte meiotic competence
– Van Wettere et al., 2011 Therio 75:1301-10
• Ad lib to 235 or restrict feeding from 123-235 days
• AL increases estrus by 235 (98 vs 91%) reduces AAP (174 vs 178 d). Miller et al., JAS 2011 89:342-54

15. Effect of gilt development diets differing in lysine
energy ratio on response to puberty induction in
replacement gilts at 175 d
140
112,000 g = 640 g/d
130 97,000 g = 554 g /d
120
110
diet 1
100
d2
90
kg
d3
80
70
60
50
40
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Week
(100 days) (175 days)

16. Effect of Lysine:energy ratio on PG600
effects on Puberty induction
High Medium Low P
N 34 36 36
Estrus (%) 90.9 83.0 72.2 <.05*
Durest (h) 47 56 52 ns
OV (%) 91.9 89.5 86.4 ns
CL 16.4 18.5 21.5 ns
Knox et al., 2004, unpublished
Cia et al., 1998; Anim. Sci. 66:457-63

17. Effect of 4-Day Boar Priming For 160-180 d old
Gilts On PG600 Estrus Response
Treatment
NBE NBE BE BE
Item 160 180 160 180
N 43 38 45 39
Estrus, %a 46.5 38.5 58.7 60.0*
Ovul., %b 65.1 71.8 77.8 72.2
30 minutes of fence-line BE for 4 days or no exposure prior to PG600

18. 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.

19. Effect of adjacent boar housing on cyclic activity
following hormone induction of puberty in gilts
No Boar Boar
2nd estrus 12/23 20/23 *
2nd ovulation 12/23 18/23 *
Paterson and Lindsay, 1981 Anim. Prod. 32:51-54

20. Boar Exposure and Gilt Management
• Certain procedures are critical and must be
done well (Gadd 2004 Pig progress 20: 14)
• Gilts exposed to boars at 140 to 170 d show
puberty at 180 to 200 d ± 28 d (Farms range from 188-251)
– Tummaruk et al., 2009 ARS 110:108-22 (tropics)
– Foxcroft, 2005 from Beltranena 1991 (CAN)
• Provide good stressors to to stimulate
hormone release
• Minimize Bad stressors that inhibits hormone
release

21. A good stress:
Boar exposure advances estrus expression
100
cummulative estrus (%)
90
80
70 140
60
160
50
190
40
210
30
20
10
0
140 160 180 200 220 240 260
Days of age

22. Age at start of boar exposure on
synchrony
Age at BE AAP D to estrus Estrus in 10 d
160 d 179 18.9 24%
180 d 191 10.4* 67%*
200 d 210 8.3* 70%*
Van Wettere et al., 2006. Anim. Reprod. Sci. 95:97-106.

23. Early Exposure:
Age at puberty from Boar exposure (%)
35
30
25
20
15
10
5
0
140 150 160 170 180 190 200 210 220 230 240 250 260 270 280
Day of age
Johnson 2003, N = 244; Avg. 180 d (135-276) SD 24 d

24. Later Exposure
Modern Genetic Lines Differ
Line bf 1st estrus % AAP FR % TB
American diamond .79 91 225 77 10.2
Danbred USA .56 87 222 77 11.0
DK Monsanto DK44 .70 87 222 75 11.6
DK Monsanto MXP200 .71 97 209 92* 12.0
Natl. Swine Reg (Y x L) .66 90 222 77 10.6
Newsham Hybrids USA .58 88 223 78 10.5
Diff 0.21 4 16 17 1.8
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

25. Daily Boar Exposure and Twice daily
reduces AAP
Days to puberty
0 51 d
2x/week 34 d
5x/week 29 d
1x/d 19 d
% cycling in 2 weeks
0X 0
1x/d 19%
2x/2 81%
• Hughes, 2004 Pig Intl. 34:18-20

26. Fenceline or Physical Boar Exposure On
Accumulative Estrous Expression
100
Cummulative Estrus (%)
90
80
70
FBE-2x
60
FBE-1x
50
PBE-2x
40 PBE-1x
30
20
10
0
10 20 30 40 50 60 70 80
Day of age
Zimmerman et al., 1998 160 d exposure, 10 min/day

27. Duration of daily boar exposure
on puberty
70
60
50
40
days
30
20
10
0
0 2 10 30
Minutes of exposure/day
Paterson et al., 1989; Anim. Reprod. Sci. 21:115-124

28. Good Stressors
Boar Exposure Frequency and Transport on Gilt Puberty
BE (20 min)
Transport (20 min) 0 1X/d 3 X/d
Yes 0% 56% (187) 62% (171)
No 29% (186) 25% (179) 44% (183)
Hughes et al, 2007 ARS 46:159-65
Hughes et al., 97

29. Effect of boar choice
Maturity of Boars Activity of boar
Stimulus AP Type AP
No Boar 203 Control 217
6.5 mo. old Boar 206 Vocal 199
11 mo. Old boar 182 Boar + Vocalization 178
24 mo old boar 182 30 min/day begin @ 140 d
Exposure at 160 d

30. 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 48 d 34 d 19 d *
Puberty
Hughes, 2001 VIth Intl. Conf. Pig Reprod. Pre-conf. Workshop.

31. Bad Stressors
Impact of gilt floor space on puberty
Floor Gilts/pen at Pens/TRT 140 d PBE to AAP Pubertal by
space 75 d of age a V-Boar 200 d
1.13 m2 15 ~42 + 8 min/d 182 d 37%
0.77 m2 22 ~30 + 12 min/d 184 d* 30%*
1.13m2 = 12 sq. ft
Young et al., 2008 J. Anim. Sci. 86:3181-93

32. Bad stressors
Group Size on Induction
No. Gilts/Group % Cyclic by 270 d
3 57
9 78
17 80
27 81
• Not >40 and <4// give 16-22 sq. ft
• Ratio of gilts to boar should be 6:1 and if
greater then exposure time may need to be
> 10 minutes
Hughes 2001 , Intl. Conf. Pig Reprod. Pre conf. workshop

33. Bad stressors
High Ammonia negates boar exposure
• >10-20 ppm in development delays puberty
• (Malayer et al., 1987; Zimmerman et al., 1988)
• 5.0 ppm ammonia can be achieved by running fan more
which improves puberty
• Malayer et al., 1987 JAS 64:1476-83

34. Gilt Maturity at Breeding
Age 1st Wgt 1st Wgt at 1st Wgt at 1st Not Preg BA P1 BA P2
mating mating farrow wean
Farm A 230 124 181 156 11% 10.7 11.6
Farm B 275 145 189 165 15% 11.8 11.6
* * * *
• > Wgt. gain in 1st gestation = > FR (favors intermediate age)
• Hoving et al., ARS 122:82-9

35. Gilt Age at 1st Service on Productivity
Early Intermediate late
Intervals +21 d +21 d
AI 222 243 264
Age at farrow 337 356 371
Age at Cull 982 1014 1024
Parity at cull 4.8 5.0 4.9
BA 52.0 53.8 53.6
Cozler et al., 1998 pig progress 14:8-9; favors intermediate

36. Gilts age at service on TB
11.8
11.6
11.4
11.2
11
10.8
10.6
10.4
10.2
10
<190 200 210 220 230 240 250 >250
• Goss, 2003 Pig Intl. 33:21-24 (Brazil, C-22 13,000 litters); favors intermediate

37. Gilt maturity and born alive
12
11.5
11
10.5
10
9.5
9
8.5
8
Age of mating
• Schukken et al., 1994 JAS 72:1387-92 (14,000 gilts; favors older age )

38. Gilt weight at mating and P2 BF (mm) and total
pigs to 4th parity
70
60
50
40
30 P2 at AI
20 total pigs
10
0
115 125 135 145 155 165
Weight at mating
• Goss, 2003 Pig Intl. 33:21-24 (Challinor et al., 1996); favors intermediate BF and weight

39. Impact of weight at first service on
Productivity (total born P 1-3)
135 140 154 166 >170 favors intermediate
kg
Source: Williams et al., 2005

40. Gilt maturity and herd life
900
850
800
days
750
700
650
600
Days at mating
• Schukken et al., 1994 JAS 72:1387-92 (favors intermediate age)
• Breeding before 275 d reduces risk by 20% compared to older (Engblom et al., 2008
JAS 86:432-41)

41. Age at Puberty and Herd Longevity
<185 >185 favors
n 165 945
BW 200d 131 128 +
GR (g/d) 784 760 * AAP/Faster/heavier
BF 20.6 17.8 * >BF
1st serve 258 261 ns
P 1-3 Born alive 24.8 22.5 * All the above
Age at removal 513 509 ns
Young et al., 2008 JAS 86:3181-93

42. Greater productivity with mating at 2nd estrus than
later cycles on total born P 1-3
Source: Williams et al., 2005

43. AAP and Sow Fertility
• First 1/3rd of gilts expressing puberty associated with
estrus in 10 d post weaning (r = -0.50)
• Sterning et al., 1998 JAS. (favors younger ages)
• Lines selected for early AAP have a shorter wean to
estrus, and more sows reaching P5
• Holder et al., Anim. Sci. 1995 61:115-21

44. Thoughts on developing gilts
• Genes for rapid growth inherent in modern selection
• Immune system and reproductive maturity do not develop as quickly as growth
traits
– High culling/replacement rates will not allow herd immune stability which increases following
P2
• Growth management appears critical to allow reproductive maturity without
excessive body maturity
– Gilts need a period of slow down or else they will get too big
• Fatter/slower growing gilts less likely to be culled (Hoge and Bates 2011 JAS 89:1238-45)
– How and when this is done is important (lysine/energy/stress)
– Diet manipulation from puberty to breeding no effect on longevity/productivity
(Rozeboom et al., 1996 JAS 74:138-150)

45. Gilt and Reproductive failures lead
North American Farm (%) Fertility Concerns
% of farms
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
• Knox et al., unpublished
• Associated with higher culling: returns, stillborns
• Hoge and Bates 2011 JAS 89:1238-45; Engblom et al., 2008 JAS 86:432

46. Getting gilt fertility right the first time
is critical for longevity
Gilts conceiving at Gilts returning at P value
1st AI 1st AI
Age entry 180 180
Age at 1st mating 257 257
Age at 1st conception 259 320 *
Parity at removal 6.2 5.6 *
Lifetime pigs born 69.7 61.9 *
Koketsu et al., J. Vet med. Sci. 61:1001-1005 1999

47. Repeat Service Females
Pregnancy Failures
• Farrowing rate
– decreases 10% in re-serviced females
• Japan; (Koketsu 2003 J vet med sci. 65:1287-91 (N= 539 herds)
– Repeated service females 13% less likely to farrow
• Tummaruk et al Prev. vet med 2010 96:194-200 (Thailand, ~9000 females
– Previous reproductive failure = 17% more likely to be open
– Average re-service rate is 16% (gilts) and 14% (P1-2 sows).
– Vargas et al., Prev. vet Med 2009 89:75-80 and ARS 2009 113:305-10
– PIC females in Brazil

48. Diagnosing Sources of Reproductive
Failure
• By 260 days of age 16% of gilts fail to show estrus (but had ovulated
and had a red swollen vulva)
• Eliasson ARS 1991 25:255-64
• Return to estrus after mating the most common failure
• Vargas et al., Prev. vet Med 2009 89:75-80
• ARS 2009 113:305-10
• Reproductive Tract Lesions
• 52% None
• 25% Inactive ovaries
• 23% Paraovarian cysts
• 6% Ovarian cysts
• 1% Uterine disorders
– Heinonen et al., 1998 (1700 tracts)

49. Reproductive Failure Diagnostics
• In a herd with evident reproductive failures
• 67% culled for repeat breeding and irregular returns
– Diagnostics
• 50% no pathology
• 69% cycling
• 17% inactive ovaries (61% endometritis)
• 14% cysts
• 27% endometritis
– Dalin et al., 1997 Acta vet scand. 38:253-62

50. Gilt Health
• Data suggests farm specific impact not system type
• Krietr et al., dtsch Tierarztl Wochenschr 2004 111:462-6
• Lesions, Respiratory, GI, Genitourinary,
• High rates of gilt replacement destabilizes herd health
– Gilts have lower immunity for offspring
– Greater incidence of Mycoplasma, PRRS
• Moore NHF April 2004 6-10
• Diseases that impact reduce feed intake and nutrient absorption will
reduce growth rate, health and Immune status and impact puberty
• PCV2
• PRRS
• iletis

51. 2006 USDA Disease Prevalence in US Swine
Herds
Breeding Breeding herd G-F G F vaccinates
herd vaccination
PRRS 18.8 27% 23.0
Mycoplasma 8.8 5.0
Ileitis 24.0
Mycoplasma 35% 24.0
H1N1 5.6 28% 23.1
Gastric ulcers 9.3 14.5
Hemorrhagic bowel 18.9

52. Specific Factors Influencing Gilt health
• Sanitation in barn
– Assoc. with discharges
• Immunity affected by time of cross fostering
– Ab and CMI transferred over 12 h from dam
• Bandrick et al., Vet Rec. 2011 168:100-
• Diseases with potential impact on future gilt fertility
– PCV2 (PR)
– Madson et al., Vet pathol. 2009 46:707-16
– SI
• Increased mortality in piglets, growers, finishing, aborts
– Pejsak et al., Medycyna Weterynaryjna 61:1154-59 2005

53. Take Home
• Gilt replacement rates are an old problem we have not addressed well
– Herd differences are real and multi-factorial for all below
– Days to maturation of gilt system takes time
– Gilt health management in G-F allows GR
– 1st breeding success a key
– Selection approach involves mother, litter comparisons, traits
–
– Growth management
– Breeding age has targets for age, weight, maturity, BF
– There are ways to maximize ESTRUS induction using boar exposure and management
approaches

54. Thanks for your attention!