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Introduction to Fetal Programming

Introduction to Fetal Programming. Dr. Jeff Lehmkuhler Extension Beef Specialist Animal & Food Sciences ANR Update Fall 2013. Our Destination. Bovine Fetus Size. 35 days 90 days 120 days 180 days 240 days. Barker Hypothesis. Fetal Origins Hypothesis = Fetal Programming

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Introduction to Fetal Programming

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  1. Introduction to Fetal Programming Dr. Jeff Lehmkuhler Extension Beef Specialist Animal & Food Sciences ANR Update Fall 2013

  2. Our Destination

  3. Bovine Fetus Size • 35 days • 90 days • 120 days • 180 days • 240 days

  4. Barker Hypothesis • Fetal Origins Hypothesis = Fetal Programming • Traced back 1944 Nazi occupied Holland • Calorie ration down to ~ 500 / d • Offspring higher disease rates

  5. Fetal Programming • Maternal stimuli during pregnancy that can affect fetal development, as well as postnatal growth & health • Maternal plane of nutrition influences / alters genetic expression of offspring • In some species, lasts for several generations • Provide opportunity of phenotypic variation in “Fixed” genotypes = Epigenetics

  6. Epigenetics • Heritable changes in gene expression resulting in alterations to chromatin structure • DNA methylation, Histone modification (acetylation), noncoding microRNAs http://micro.magnet.fsu.edu/cells/nucleus/chromatin.html

  7. DNA Methylation Example • Most DNA is methylated (CH3) • Regions not methylated are close to regulatory region • Variation in methylation in different tissues • S-adenosylmethionine = methyl donor influenced by diet • Gestating Ewes restricted folate, vitamin B12, betaine, choline, methionine = obesity and impaired immune systems of progeny as adults

  8. Estimated Net Energy Requirementsfor 2-, 3-, and 5-year old Cows Calving Breeding Season 75% Fetal Growth Wean Mcal/d Months Since Calving First Trimester 1996 Beef NRC

  9. Past Thoughts • Dry, mid-gestational cow lowest nutritional needs • Best time to “cheat” nutritionally • Little fetal development = low nutrient need • High supplementation during late gestation = heavier Birth Weights Were We Wrong?

  10. Placental Development • Placentome = Cotyledons (Fetus) + Caruncles (Maternal) • Growth occurs throughout gestation • First 2/3 of gestation primary growth • Growth slows last trimester • Blood flow 4.5-fold increase last ½ gestation

  11. Nutrition & Placenta • Nutrient restriction during early/mid-gestation • Lowered placentome weight • Altered Vascularity of placenta • Protein Supplementation on Day 190 = 2X blood flow • Restriction reduces number of cotyledons, not caruncles

  12. Fetal Organ Development • Restricted Cows from day 30-125 of gestation • Fetuses had enlarged hearts & brains • Feeding cows back to same condition score by day 220 of gestation = No differences by d 245 • Vascular of intestines, size of liver, lungs, pancreas, kidney, perirenal fat have also been shown to be impacted by nutrition of the dam

  13. Maternal Nutritional Restriction on Fetal Muscle Development Muscle Fiber Numbers SET No Increase after Birth Du et al., 2010 JAS

  14. Muscle Development • Animals born with set number of muscle fibers • Hypertrophy occurs after birth = Muscle fiber size increases • Low priority tissue = Susceptible to deficiency

  15. Nutrient Restriction Skeletal Muscle • Nutrition during pregnancy explained 20% of variation in birth weight (Robinson et al., 2013) • Current research shows mixed results on muscle fiber number / diameter / carcass traits

  16. What’s Been Reported – Few Examples

  17. Timing of Cow Nutritional Plant & Impacts on Cattle Light = Time of nutrition Dark = When Impacts Progeny

  18. So What = Theories • We know – Birth weight, Colostrum, and placental development impacted • We don’t know – Consistently what impact this will have on growth, fertility, health, etc… • Add’l research in area will be forthcoming and help unravel

  19. Recommendations? • Manage diet to meet / slightly exceed nutritional requirements at various stages of production • Critical points are late gestation / early lactation / early gestation • Often overlooked, hay quality ??, grass availability??, fescue toxicity?? • Maintain BCS in 5-6 at critical points, Keeping Cows at Par / + Energy balance = Fertility

  20. Mineral Update • Matthews/Burris et al. Selenium Research • Support mix of organic / inorganic Se in mineral • Grass tetany • Can occur in fall / winter • Lush pasture (N & K fertilizer) & cereal grain silage • Spreadsheet comparison of IRM Rec to 4 oz

  21. Forage Quality • Going to be mixed = Recommend testing • Late cuttings may be low quality • Late Late cuttings may have vegetative regrowth to offset quality • Second cuttings should be decent • Silage quality likely quite good (high grain content)

  22. Thoughts / Questions Underfed Cow?

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