2012 Leman Pre-Conference Reproduction Workshop                   Rob Knox          Department of Animal Sciences         ...
Premise of Gilt Development and Sow Longevity• How we develop Gilts impacts their maturity/fertility  at mating and in sub...
-High culling rates-               an old problem?– From 1960 to 2000 (NHF Review 2004)   • Culling rate      No. of Studi...
Why a gilt won’t make it to parity 5                      Puberty                       delay                     No puber...
The realities of Gilt Replacement• Great variation in   – gilt growth/body development   – Days to pubertal estrus   – sym...
In prepubertal gilts, proportions of giltsshowing brain and ovary maturation by age              100                      ...
The Physiology of Gilt Puberty•   Ovaries/uterus can grow and respond by 120 d of age•   (Guo, et a., 1998 JAS 163-68)•   ...
Most but not all gilts express estrus by 260 d of age                              Estrus in gilts following Boar Exposure...
Puberty Can be influenced by      Farm, Breed, ManagementHughes et al., 1990; J. Reprod. Fertil. Suppl. 40:323-341
Where Can Selection Pay Off for Gilt                  Fertility?                      AVG            SD    CV      h2 AAP ...
Selection of gilts for standing and Vulva symptoms at     pubertal estrus improves subsequent generationsRydhmer et al., 1...
Gilt Selection for fertility• In Mothers of Gilts    – Offspring of early puberty mothers (d 185) cycle earlier with more ...
Higher Growth Rate Reduces AAP• Higher growth rate (>600 g/d) to 140-165 d (r = -0.40) with AAP      •   Tummaruk et al., ...
Feeding the developing gilt• Energy intake in G-F changes growth, weight and BF not reproductive  measures        • (FF E2...
Effect of gilt development diets differing in lysine    energy ratio on response to puberty induction in                 r...
Effect of Lysine:energy ratio on PG600      effects on Puberty induction                            High         Medium   ...
Effect of 4-Day Boar Priming For 160-180 d old        Gilts On PG600 Estrus Response                                      ...
Effect of PG600 and No Daily Boar Contact or    Daily Boar Contact on 1st and 2nd Estrus                            NBE   ...
Effect of adjacent boar housing on cyclic activityfollowing hormone induction of puberty in gilts                       No...
Boar Exposure and Gilt Management• Certain procedures are critical and must be  done well (Gadd 2004 Pig progress 20: 14)•...
A good stress:                                     Boar exposure advances estrus expression                         100cum...
Age at start of boar exposure on                    synchrony   Age at BE                        AAP                   D t...
Early Exposure:             Age at puberty from Boar exposure (%)      35      30      25      20      15      10        5...
Later Exposure                      Modern Genetic Lines DifferLine                             bf           1st estrus % ...
Daily Boar Exposure and Twice daily                     reduces AAP                                      Days to puberty  ...
Fenceline or Physical Boar Exposure On          Accumulative Estrous Expression                                   100     ...
Duration of daily boar exposure                  on puberty              70              60              50              4...
Good Stressors   Boar Exposure Frequency and Transport on Gilt Puberty                                           BE (20 mi...
Effect of boar choiceMaturity of Boars         Activity of boarStimulus             AP   Type                APNo Boar    ...
Percent of gilts pubertal and days to            puberty in response to LIBIDO                 No Boar           Low Libid...
Bad Stressors    Impact of gilt floor space on puberty Floor         Gilts/pen at     Pens/TRT      140 d PBE to   AAP    ...
Bad stressors                          Group Size on Induction    No. Gilts/Group                  % Cyclic by 270 d    3 ...
Bad stressorsHigh Ammonia negates boar exposure• >10-20 ppm in development delays puberty     • (Malayer et al., 1987; Zim...
Gilt Maturity at Breeding           Age 1st   Wgt 1st   Wgt at 1st   Wgt at 1st   Not Preg   BA P1   BA P2           matin...
Gilt Age at 1st Service on Productivity                      Early                 Intermediate        lateIntervals      ...
Gilts age at service on TB                11.8                11.6                11.4                11.2                ...
Gilt maturity and born alive                12               11.5                11               10.5                10  ...
Gilt weight at mating and P2 BF (mm) and total                      pigs to 4th parity                70                60...
Impact of weight at first service on                       Productivity (total born P 1-3)                                ...
Gilt maturity and herd life         900         850         800  days         750         700         650         600     ...
Age at Puberty and Herd Longevity                        <185        >185        favorsn                       165        ...
Greater productivity with mating at 2nd estrus than                     later cycles on total born P 1-3Source: Williams e...
AAP and Sow Fertility• First 1/3rd of gilts expressing puberty associated with  estrus in 10 d post weaning (r = -0.50)   ...
Thoughts on developing gilts•   Genes for rapid growth inherent in modern selection•   Immune system and reproductive matu...
Gilt and Reproductive failures leadNorth American Farm (%) Fertility Concerns                                             ...
Getting gilt fertility right the first time        is critical for longevity                            Gilts conceiving a...
Repeat Service Females                Pregnancy Failures• Farrowing rate   – decreases 10% in re-serviced females       • ...
Diagnosing Sources of Reproductive                Failure• By 260 days of age 16% of gilts fail to show estrus (but had ov...
Reproductive Failure Diagnostics• In a herd with evident reproductive failures       • 67% culled for repeat breeding and ...
Gilt Health• Data suggests farm specific impact not system type         • Krietr et al., dtsch Tierarztl Wochenschr 2004 1...
2006 USDA Disease Prevalence in US Swine                   Herds                    Breeding   Breeding herd   G-F    G F ...
Specific Factors Influencing Gilt health• Sanitation in barn   – Assoc. with discharges• Immunity affected by time of cros...
Take Home•   Gilt replacement rates are an old problem we have not addressed well     – Herd differences are real and mult...
Thanks for your attention!
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Dr. Rob Knox - Gilt Management/Puberty Induction and Sow Longevity/Productivity

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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.

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  • As gilts age, the brain and ovaries mature. With maturation, release of the hormone LH occurs in pulses, and follicle size increases. These events precede puberty. PG600 injection should occur before puberty but close to time of natural attainment.
  • Most breeding farms report fertility concerns:With sows bred within 7 d pregnancy failure, gilt estrus induction
  • Dr. Rob Knox - Gilt Management/Puberty Induction and Sow Longevity/Productivity

    1. 1. 2012 Leman Pre-Conference Reproduction Workshop Rob Knox Department of Animal Sciences University of Illinois, Champaign-Urbana, IL USA 61801
    2. 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. 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. 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. 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. 6. In prepubertal gilts, proportions of giltsshowing 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. 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. 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 Days72.5% (n = 700/965) estrus in 80 days (AASV Pre Conf. Symp. Foxcroft, 2002)
    9. 9. Puberty Can be influenced by Farm, Breed, ManagementHughes et al., 1990; J. Reprod. Fertil. Suppl. 40:323-341
    10. 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. 11. Selection of gilts for standing and Vulva symptoms at pubertal estrus improves subsequent generationsRydhmer et al., 1994 J. Anim. Sci. 72:1964-1970 (Yorkshire)
    12. 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. 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 d577 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. 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. 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. 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 nsKnox et al., 2004, unpublishedCia et al., 1998; Anim. Sci. 66:457-63
    17. 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 72.230 minutes of fence-line BE for 4 days or no exposure prior to PG600
    18. 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. 19. Effect of adjacent boar housing on cyclic activityfollowing 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. 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. 21. A good stress: Boar exposure advances estrus expression 100cummulative 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. 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. 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 ageJohnson 2003, N = 244; Avg. 180 d (135-276) SD 24 d
    24. 24. Later Exposure Modern Genetic Lines DifferLine bf 1st estrus % AAP FR % TBAmerican diamond .79 91 225 77 10.2Danbred USA .56 87 222 77 11.0DK Monsanto DK44 .70 87 222 75 11.6DK Monsanto MXP200 .71 97 209 92* 12.0Natl. Swine Reg (Y x L) .66 90 222 77 10.6Newsham Hybrids USA .58 88 223 78 10.5 Diff 0.21 4 16 17 1.8Moved from pens of 25 into crated 1600 sows facility at 180 d and exposed to a V boar 2/x /dMoeller et al., JAS 2004 82: 41-53
    25. 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. 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 ageZimmerman et al., 1998 160 d exposure, 10 min/day
    27. 27. Duration of daily boar exposure on puberty 70 60 50 40 days 30 20 10 0 0 2 10 30 Minutes of exposure/dayPaterson et al., 1989; Anim. Reprod. Sci. 21:115-124
    28. 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 46:159-65Hughes et al., 97
    29. 29. Effect of boar choiceMaturity of Boars Activity of boarStimulus AP Type APNo Boar 203 Control 2176.5 mo. old Boar 206 Vocal 19911 mo. Old boar 182 Boar + Vocalization 17824 mo old boar 182 30 min/day begin @ 140 dExposure at 160 d
    30. 30. Percent of gilts pubertal and days to puberty in response to LIBIDO No Boar Low Libido High LibidoPuberty 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 *PubertyHughes, 2001 VIth Intl. Conf. Pig Reprod. Pre-conf. Workshop.
    31. 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. ftYoung et al., 2008 J. Anim. Sci. 86:3181-93
    32. 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 minutesHughes 2001 , Intl. Conf. Pig Reprod. Pre conf. workshop
    33. 33. Bad stressorsHigh 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. 34. Gilt Maturity at Breeding Age 1st Wgt 1st Wgt at 1st Wgt at 1st Not Preg BA P1 BA P2 mating mating farrow weanFarm A 230 124 181 156 11% 10.7 11.6Farm 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. 35. Gilt Age at 1st Service on Productivity Early Intermediate lateIntervals +21 d +21 dAI 222 243 264Age at farrow 337 356 371Age at Cull 982 1014 1024Parity at cull 4.8 5.0 4.9BA 52.0 53.8 53.6 Cozler et al., 1998 pig progress 14:8-9; favors intermediate
    36. 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. 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. 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. 39. Impact of weight at first service on Productivity (total born P 1-3) 135 140 154 166 >170 favors intermediate kgSource: Williams et al., 2005
    40. 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. 41. Age at Puberty and Herd Longevity <185 >185 favorsn 165 945BW 200d 131 128 +GR (g/d) 784 760 * AAP/Faster/heavierBF 20.6 17.8 * >BF1st serve 258 261 nsP 1-3 Born alive 24.8 22.5 * All the aboveAge at removal 513 509 nsYoung et al., 2008 JAS 86:3181-93
    42. 42. Greater productivity with mating at 2nd estrus than later cycles on total born P 1-3Source: Williams et al., 2005
    43. 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. 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. 45. Gilt and Reproductive failures leadNorth American Farm (%) Fertility Concerns % of farms 0 10 20 30 40 50 60Sows bred within 7 days Irregular returns Regular returns Gilt estrus NIPIrregular 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. 46. Getting gilt fertility right the first time is critical for longevity Gilts conceiving at Gilts returning at P value 1st AI 1st AIAge entry 180 180Age at 1st mating 257 257Age 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. 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. 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. 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. 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. 51. 2006 USDA Disease Prevalence in US Swine Herds Breeding Breeding herd G-F G F vaccinates herd vaccinationPRRS 18.8 27% 23.0Mycoplasma 8.8 5.0Ileitis 24.0Mycoplasma 35% 24.0H1N1 5.6 28% 23.1Gastric ulcers 9.3 14.5Hemorrhagic bowel 18.9
    52. 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. 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. 54. Thanks for your attention!

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