Dr. Billy Flowers - Managing gene X environment interactions on reproductive performance of replacement gilts and boars through pre-weaning management at multiplication level is this a reality?
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Dr. Billy Flowers - Managing gene X environment interactions on reproductive performance of replacement gilts and boars through pre-weaning management at multiplication level is this a reality?

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Managing gene X environment interactions on reproductive performance of replacement gilts and boars through pre-weaning management at multiplication level is this a reality? - Dr. Billy Flowers, NCSU, ...

Managing gene X environment interactions on reproductive performance of replacement gilts and boars through pre-weaning management at multiplication level is this a reality? - Dr. Billy Flowers, NCSU, from the 2011 The Allen D. Leman Swine Conference, September 17-20, 2011, St Paul, MN, USA.

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Dr. Billy Flowers - Managing gene X environment interactions on reproductive performance of replacement gilts and boars through pre-weaning management at multiplication level is this a reality? Dr. Billy Flowers - Managing gene X environment interactions on reproductive performance of replacement gilts and boars through pre-weaning management at multiplication level is this a reality? Presentation Transcript

  • Preweaning Management ofReplacement Gilts and Boars W.L. Flowers North Carolina State University Raleigh, N.C.
  • Developmental Period
  • The period just prior to birth through weaningis an active period of development for boththe testicles and ovaries.
  • Most of the follicles are present at birth, but during the first 30days they begin to acquire their functional components. Birth Weaning
  • Very active period of Sertoli cell proliferation and testiculardevelopment occurs during the first 30 days of life. McCoard et al., 2003 Birth Weaning
  • 1. Pre-weaning management of replacement gilts and sow longevity2. Pre-weaning management of replacement boars and sperm production and fertility as adults.
  • Effect of Neonatal Litter Size on Sow Longevity• Study was conducted with 1820 gilts in an 80,000 sow commercial production system.• Only used litters that had between 10 and 14 pigs born alive.• Litter size was adjusted after birth to either < 7 pigs (n=899) or > 10 pigs (n=921).• All sows in the study had pigs fostered on and off.
  • Effect of Neonatal Litter Size on Sow Longevity• After weaning, all females were managed similarly in that they were housed in the same barns during the nursery and finishing phases• Study also had a boar exposure component.• All sows were bred for the first time ~ 240 days of age and then monitored through 6 parities.
  • Effect of Neonatal Litter Size on Sow Longevity• Farm management made culling decisions.• Any female that did not rebreed within 10 days of weaning or failed to farrow after insemination was considered an experimental failure in terms of longevity.
  • > 10 pigs nursing < 7 pigs nursing
  • Effect of Neonatal Lactation Litter Size on Sow Longevity 100 p < 0.05 *Females remaining in production (%) 90 80 * 70 * 60 * < 7 piglets 50 * * * * * 40 ** 30 E = Entry 20 B = Breeding - gilts 10 F = Farrowing R = Rebreeding > 10 piglets 0 E B F1 R1 F2 R2 F3 R3 F4 R4 F5 R5 F6 Production phase (Flowers et al., in press)
  • Effect of Neonatal Lactation Litter Size on Farrowing Rate 100 < 7 piglets (88.7%) * > 10 piglets (83.3%) p < 0.05 90Farrowing rate (%) 80 70 60 0 1 2 3 4 5 6 Sow Parity (Flowers et al., in press)
  • Effect of Neonatal Lactation Litter Size on Number Born Alive 12 < 7 piglets (11.0 + 0.1) * p < 0.07 > 10 piglets (10.5 + 0.2)Number Born Alive 11 10 9 0 1 2 3 4 5 6 Sow Parity (Flowers et al., in press)
  • How does the preweaning environment ofreplacement gilts influence their longevity?
  • + LH, FSHEstrogens
  • Most of the follicles are present at birth, but during the first 30days they begin to acquire their functional components. Birth Weaning
  • Estrus Response of Crossbred Gilts given Boar Exposure at 140 days of age 50 Early LateNumber of Gilts in Estrus Responders Responders 40 30 20 10 0 0 5 10 15 20 25 30 35 40 45 50 55 60 Days from Onset of Boar Exposure
  • Effect of Neonatal Environment on Female Response to Early Boar Exposure Neonatal EnvironmentVariables < 7 pigs > 10 pigsProportion of gilts in estrus 77.0* 53.028 days after exposure (%) †Average number born 11.3 10.8alive – early respondersAverage number born 10.3 10.2alive – late responders † p < 0.08* p < 0.05 (Flowers et al., in press)
  • Effect of Neonatal Lactation Litter Size on Sow Longevity 100 p < 0.05 *Females remaining in production (%) 90 80 * 70 * 60 * < 7 piglets 50 * * * * * 40 ** 30 E = Entry 22% 20 B = Breeding - gilts 10 F = Farrowing R = Rebreeding > 10 piglets 0 E B F1 R1 F2 R2 F3 R3 F4 R4 F5 R5 F6 Production phase (Flowers et al., in press)
  • How does the preweaning environment of replacement gilts influence their longevity?Possibly, by affecting how efficiently they pro-duce and/or respond to reproductive hormones.
  • Neonatal Litter Size and Response to Low Dose of PG600 Gilts exhibiting vulvar swelling (%) 100 * 80 * < 7 piglets > 10 piglets 60 * *p < 0.05 40 20 0 80 100 120 140 160 Age of gilts (days)
  • 1. Pre-weaning management of replacement gilts and sow longevity2. Pre-weaning management of replacement boars and sperm production and fertility as adults.
  • Very active period of Sertoli cell proliferation and testiculardevelopment occurs during the first 30 days of life. McCoard et al., 2003 Birth Weaning
  • 40 boars Fall-Born Spring-BornFarrowing (n=20) (n=20) 1 day 1 day 6 pigs/ >9 pigs/ 6 pigs/ > 9 pigs/ of age of age litter litter litter litter (n=10) (n=10) (n=10) (n=10) Weaning(3 weeks) Pens of 10 Pens of 10 Co-mingled Co-mingled 8 weeks Pens of 4 Pens of 4 Co-mingled Co-mingled20 weeks Individual Pens Individual Pens 2 years
  • Boars - ~90 weeks of ageLitter of 6 Litter of 10
  • Effect of Lactation Litter Size on Reproductive ParametersParameter 6/litter >9/litter P valueTotal spermatozoa/ 98 + 3 86 + 4 0.01ejaculate (x 109)Motility/ejaculate (%) 87 + 5 83 + 5 0.39Normal morphology/ 89 + 6 83 + 4 0.47ejaculate (%)Normal acrosome 90 + 5 83 + 6 0.49morphology (%) Griffith et al., 2006
  • Effect of Lactation Litter Size on Reproductive ParametersParameter 6/litter >9/litter P valueAcrosin activity (%) 95 + 5 93 + 4 0.36Normal capacitation (%) 84 + 6 75 + 7 0.26Seminal plasmaproteins/ejaculate 17 + 2 10 + 2 0.11(relative units)Proportion of pigletssired in heterospermic 69 + 4 31 + 6 0.02matings Griffith et al., 2006
  • Developmental Period
  • Relative Importance of Pre-weaning Growth Characteristics on Sow LongevityVariables R2 P valuePre-weaning gain 21.0 < 0.05Weaning weight 15.3 < 0.05Birth weight 5.1 < 0.10Other variables 58.6 (Flowers et al., in press)
  • FSH ~ 40 days of age Control ~ 40 days of age
  • Summary• Strategic cross-fostering of litters with potential replacement animals appears to have a positive effect on adult reproductive performance.• In sows, it might enhance their ability to respond to or produce reproductive hormones (sensitivity)• In boars, it increases testicular size and sperm output.
  • What We Don’t Know• At the present time, it is not known how much of a reduction in litter size is needed to effectively improve in each of these situations.• The answer to this question could be related to a piglet’s birth weight.
  • Relationships between Piglet Birth Weights and Organ Weights Small 0.24 Intestines LiverOrgan Weight (lbs) 0.20 0.16 Brain 0.12 0.08 0.00 0 1.0 2.0 3.0 4.0 Birth Weight (lbs) (Adapted from Foxcroft et al., 2009)
  • Relationship between Number Born Alive and Litter Birth Weights 15Number Born Alive 14 13 12 11 10 9 8 0 10 20 30 40 50 Litter Birth Weight (lbs)
  • Relationship between Number Born Alive and Litter Birth Weights 3 lb average Birth weight 15Number Born Alive 14 Replace- 13 ment gilt 12 or boar 11 candidates 10 9 8 0 10 20 30 40 50 Litter Birth Weight (lbs)
  • Number Born Alive and Litter Birth Weights Market animals 1.5 lb average 3 lb average birth weight birth weight 15Number Born Alive 14 Replace- 13 ment gilt 12 or boar 11 candidates 10 Strategic 9 cross- 8 fostering 0 10 20 30 40 50 Litter Birth Weight (lbs)
  • Developmental Period Birth Weights Weaning Weights Early Responders (for gilts)
  • Graduate Students UndergraduatesDr. Kara Stewart Nikhol GarbacikDr. Kyle Lovercamp Stefani GarbacikSara Crowell Kristy KinneyFrancis Turner Lisa ThompsonJennifer Griffith Allison Collins
  • Effect of Birth Weight on Parity 1 Characteristics Piglet Birth WeightsReproductivePerformance > 3.6 lbs 2.0 - 2.8 lbsAge at puberty 170 + 10 184 + 6(days)Ovulation rate 15.3 + 0.7 12.9 + 0.7Embryo survival 83 + 7 68 + 7(%) Flowers, unpublished
  • Possible Mechanisms Nutrient AvailabilityBirth 3 weeks 8 weeks 12 weeks 40 weeks Sow’s milk Increasedlimits piglet responsiveness growth of gonads & brain Development of piglets from small litters not limited as much
  • Possible Mechanisms Mitogens in Milk Birth 3 weeks 8 weeks 12 weeks 40 weeksGut closure in Increased pigs still not function ofcomplete by gonads & brain 3 to 4 days Pigs from small litters consume more milk and these compounds
  • Birth Weights of Replacement Gilts• Significant increase in litter size in highly prolific sow lines has occurred.• There is a well established inverse relationship between litter size and piglet birth weight.• There is evidence that as birth weight decreases so does organ development.
  • Typical Relationship between Productivity and Longevity in Sows 13 12 Number born alive 11 10 9 8 0 1 2 3 4 5 6 7 8 Sow Parity
  • Typical Relationship between Productivity and Longevity in Sows 13 Annual culling rates for sows 12 are 40 – 60%. Number born alive 11 Of this, highest proportion is after parity 1. 10 9 8 0 1 2 3 4 5 6 7 8 Sow Parity
  • Effect of Neonatal Environment on Growth 100 Fall Spring * * 80 *Body weight (kg) 60 * 40 * * 20 < 7 pigs/litter > 10 pigs/litter 0 0 9 12 15 18 0 9 12 15 18 Age (weeks)