Rodolfo Cardoso, Texas A&M University Aug. 29, 2018

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1 Rodolfo Crdoso, Texs A&M University Aug. 29, 28 Nutritionl Progrmming of Puerty in Bos indicus-influenced Heifers PRESENTATION OUTLINE Importnce of timing puerty in replcement heifers B. turus vs. B. indicus (Brhmn)-influenced Rodolfo C. Crdoso, D.V.M., Ph.D. Assistnt Professor Deprtment of Animl Science Nutritionl progrmming of puerty -- Hormones nd Neuroendocrine Mechnisms -- Timing (Stir-Step Approch) -- Dietry Energy Source -- Interction of pre-nd postntl nutrition on puertl progrmming ARSBC Symposium, Ruidoso, NM - 28 IMPORTANCE OF THE TIMING OF PUBERTAL ONSET IN HEIFERS million replcement eef heifers enter the U.S. cow herd nnully Lifetime productivity is hevily-dependent upon heifer s ility to rech erly sexul mturtion (GOAL: st clf s 2-yer-olds) Conceiving during the first 2 dys of the reeding seson s yerling increses the proility of continued erly clving nd longterm retention in the herd Multiple estrous cycles efore trgeted first reeding positively influences fertility Cows must wen to 5 clves to py for the cost of their own development; thus longevity is extremely importnt SEQUENCE OF EVENTS LEADING TO PUBERTY MATURATION OF THE REPRODUCTIVE NEUROENDOCRINE AXIS SECRETION OF GONADOTROPINS OVARIAN STIMULATION (Folliculr Development/Estrous Behvior) UTERINE DEVELOPMENT AND OVULATION (Trct Score) ABILITY TO BECOME PREGNANT MAIN FACTORS AFFECTING SEXUAL MATURATION IN THE HEIFER GENETICS Genetics (Breed Type/Mture Body Weight) Pre- nd Post-Wening Nutrition Criticl Body Weight/Adiposity/Nutritionl imprinting ARSBC 28, Ruidoso, N.M.

2 Rodolfo Crdoso, Texs A&M University Aug. 29, 28 NUTRITIONAL PROGRAMMING OF PUBERTY IN HEIFERS Jersey-Brown-Swiss-Angus-Hereford-Simmentl-Limousine-Chrolis-Brhmn B 2-LB MATURE COWS Birth Wen or Purchse BW (l) Wening Breeding Seson 6 Nov De c J n Fe Mr Apr 6-75 dy Breeding Seson Puertl Puertl Puertl Onset Onset Onset Nutritionl Progrmming 6 l. l ADG 66 l (55% MBW) 6 l.2 l ADG 78 l (65% MBW) 6 l Nutritionlly-Progrmmed 78 l (65% MBW) Age (mo) Fe Nov. April Leptin nd Puerty in Heifers 75 Nutritionl Progrmming of Puerty in Beef Heifers The gol of nutritionl progrmming is to crete metolic imprint during the erly juvenile period t the hypothlmic level tht results in n ccelerted timing of puerty BW, kg Leptin, ng/ml to -6 - to -2-9 to -8 Pooled SEM:2. Pooled SEM:. -5 to Weeks reltive to puerty - to Appetite nd stiety Neurite outgrowth GnRH secretion Permissive fcilittor of puerty Grci t l., 22 Body Weight nd Averge Dily Gin Circulting Insulin, IGF- nd Leptin Body Weight (kg) Propionte:Acette...2. Insulin (ng/ml) IGF- (ng/ml) Leptin (ng/ml) Week of Experiment P <. Allen et l., J. Anim. Sci. 22 P <.5 P <.2 P =. Allen et l., J. Anim. Sci. 22 ARSBC 28, Ruidoso, N.M. 2

3 Rodolfo Crdoso, Texs A&M University Aug. 29, 28 Puerty ttinment Stir-Step Nutritionl Regimen BW (Kg) 2 Nutritionl Progrmming Puertl Onset Period I Period II Period III Period IV : ADG = Kg/dy : ADG =.5 Kg/dy Age (mo) 5 Puerty (%) BW, kg Nutritionl Model SS- Leptin (ng/ml) Circulting Leptin SS- When does the metolic progrmming for erly puerty occur? Cn we nutritionlly lter the timing of puerty while optimizing other spects of growth nd development? Arrows: Diet trnsition Age, mo Arrows: Diet trnsition Time (Wk) Crdoso et l., 2, J. Anim. Sci. Heifers puertl (%) Stir-Step Nutritionl Regimen Progrms the Onset of Puerty in Beef Heifers Age 8 mo 9 mo mo mo 2 mo mo LC HC SS- Optiml Timing SS results in ~ 7% overll svings in feed costs during the development period Time (Wk) c c Crdoso et l., 2, J. Anim. Sci. Nutritionl Progrmming of Puerty in Beef Heifers Dietry Energy Source BODY WEIGHTS AND ADG OF HEIFERS FED AT A LOW OR HIGH RATE OF GAIN USING TWO DIETARY ENERGY SOURCES Body weight (kg) Averge Dily Gin (kg/d) ng/ml 2. l/dy ADG. l/dy ADG Men ge (wk) P <.2 P <.; P <.7; P <. HC- HF-, P <. Allen et l., J. Anim. Sci. 28 Switch to Common Diet Puerty Allen et l., J. Anim. Sci. 28 ARSBC 28, Ruidoso, N.M.

4 Rodolfo Crdoso, Texs A&M University Aug. 29, 28 ROLE OF MATERNAL NUTRITIONAL STATUS? Nutritionl Progrmming of Puerty in Beef Heifers Interction of pre-nd postntl nutrition on puertl progrmming Low Gin nd High Gin Heifers Body Condition Score BW (l) Weeks RESULTS TO DATE Chnges in circulting concentrtions of leptin (dms) An increse in the numer of GnRH neurons in close pposition to NPY neurons due to low mternl BCS A reduction in expression of genes involved in leptin trnsport cross the lood-rin rrier Hormonl nd neuroendocrine ltertions suggest tht low mternl BCS my result in delyed puerty in the heifer offspring (to e confirmed) These neuroendocrine ltertions cn hve long-term negtive effects on reproduction (to e confirmed) SUMMARY AND CONCLUSIONS Nutritionl ccelertion of puerty is ssocited with key ltertions in the neuroendocrine system of heifers Neurl plsticity ssocited with the juvenile period ( to 8 mo of ge), provides for opportunities to nutritionllymodulte ge t puerty Mngeril pproches tht use stir-step feeding regimen cn exploit importnt efficiencies for growth, mmmry development nd timing of puerty Prentl perturtions in metolic/nutritionl sttus re likely to dely puerty in heifers nd hve long-term detrimentl effects on reproduction ARSBC 28, Ruidoso, N.M.

5 Rodolfo Crdoso, Texs A&M University Aug. 29, 28 SUMMARY AND CONCLUSIONS Puerty occurs when heifers rech out 65% of their mture weight WHO? (Genetics) Bos turus vs. Bos indicus-influenced WHEN? (Timing of BW gin) Erly development vs. lte development HOW? (Dietry Energy Source) High-Concentrte vs. High-Forge WHAT? (Prentl Environment Fetl Progrmming) Adequte vs. Indequte Mternl Nutrition however Texs A&M University Dr. Gry Willims Dr. Mrcel Amstlden (97-2) Dr. Tom Welsh Dr. Crey Stterfield Dr. Luis Tedeschi Meghn O Neil Srh West Emm Britin Crwy Youwen Zhng Crolyn Spencer Dorot Zie Michelle Grci Mrlon Mciel Acknowledgements University of Nevd Reno Dr. Brun Alves North Dkot Stte University Dr. Chung Prk Funding r.crdoso@tmu.edu ARSBC 28, Ruidoso, N.M. 5