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TAMU ANSC 107 - Growth and Development
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Lecture 15Outline of previous lectureI. Productive performanceII. GrowthIII. Milk productionIV. Efficiency of productionV. RecordsVI. ImprovementVII. TraitsOutline of current lectureI. GrowthII. Hormonesa. Endogenous peptideb. Endogenous steroidc. Anabolic steroidsLearning objectivesUnderstand the difference between growth and maturityTo be able to identify the order of growth and the order of fat depositionUnderstand how hormones affect growth in livestockGrowthIncrease in body weight until maturity is reachedIncrease in animal tissue, muscle, fat and boneMeasures of growth include: weight/unit time (WDT), height/unit time; average daily gain; days to 260 (swine); weaning weight; yearling weightTrue GrowthThe only growth that involves an increase in structural tissues. Excludes fat as storage tissueDevelopmentDirective coordination of all diverse processes until maturity is reachedInvolves growth, cellular differentiations and changes in body shapeControlled by genetic make-up of the animalMaturityState of being fully grown or developedSexual and compositional maturityPhysiological vs. chronological ageChronological age refers to the animals age in terms of units of timePhysiological age refers to stages (landmarks) of development as the animal grows from conception to maturityHyperplasia vs. hypertrophyHyperplasia-increase in number of cellsHypertrophy- increase in cell sizeEfficiency of growthEfficiency in production is defined as units of input per unit outputUnit of feed (lbs. or kg) per unit of gain (lbs. or kg)Feed conversion values are typically7:1 for cattle4:6:1 for sheep3:1-2:1 for swine2:1 for broilers1:1:1 for fishGrowth curve is curvilinearCurved line functionGrowth considered an increase in body weight so most early growth follows a straight lineTrue growth is defined as increase in body protein-true growth stops when animal reaches maturityOrder of tissue developmentAt birth, various body parts have different shapes and propertiesFor example,Horse-head and legsLamb-legsOrder of Fat depositPerinephric-internal=kidney, pelvic and heart fat=leaf fatIntermuscular fat-seam fatSubcutaneous- external fat=back fatIntramuscular-marbling-flank streakingEarly vs. Late maturingBases of USDA feeder cattle gradesLarge frame feed moreMeasures of growth in livestockBeef cattle birth weight, weaning weight, yearling weight, feedlot AGD, mature weightSheep birth weight, 60 day weight, 90 day weight, yearling weight, feedlot AGD, mature weightMeasures of growth in livestockSwine birth weight, weaning weight, days to 23- lbs.Horses growth is generally measured in hands at a certain agePoultry days to slaughter weightCorrelated responses to selection for growthSelection for growth can influence other traits as well. Some traits are influenced positively while others are influenced negativelyGenetic effects on growth and developmentGrowth is moderately to height heritable trait (h2 ranking from .3-.5)Body/Carcass compositionEnvironmental effects of growth and developmentHormonal control of GrowthWhat is a hormoneChemical substance that is secreted into the boy fluids by one cell or group of cells and has an effect on other cellsControl of bodyNervous and hormonalEndogenous peptide hormonesHormoneGrowth hormone GH (somatotropin)(bsT,oST,pST)SourceAnterior pituitary (AP)General effectsIncreased growth rateIncreased muscle to boneIncreased mature sizeDecreased fatIncrease milk productionEndogenous Peptide HormonesSomatostatin (turns growth hormone off)SourceHypothalamusGeneral effectsInhibits release of GH from APThyroxineSourceThyroidGeneral effectsPromotes energy production and oxygen consumption by peripheral tissuehelps you grow and keeps you warmInsulinsourcepancreasgeneral effectsstimulates growth by increasing the uptake of glucose and amino acids by peripheral tissues.Increase the synthesis of RHA which leads to protein synthesisEpinephrineSourceAdrenal medullaGeneral effectsRegulation of cardiovascular systemIncreased heart rateMobilizes glycogen from liverMobilizes leg muscle receptorsDilates pupilsNorepinephrineSourceAdrenal medullaGeneral effectsStimulates brain functionRegulation of cardiovascular systemDecrease heart rateGlucocorticoidsSourceAdrenal cortexGeneral effectsAffects carbohydrates metabolism and have power anti-inflammatory actions as well as adverse side effectsIncrease food intakeEndogenous steroid hormonesTestosteroneSourceTestesGeneral effectsIncrease growth rate and feed efficiencyIncreased mature sizeIncreased muscle and boneDecreased fatSlows skeletal growth (Associated with onset of puberty)EstrogenSourceOvariesGeneral effectsSlows skeletal growthHowever, exogenous estrogenic compounds promote growth rate and feed efficiency in steersCortisolStress hormoneIncrease immune systemProgesterone (pregnancy hormone)SourceCorpus LuteumGeneral effectsExogenous progestogenic compounds promote growth rate and feed efficiencyAnabolic SteroidsDiethylstilbestrol (DES)Active agentEstrogenSupplierBanned by FDA-causes human birth defectsGeneral effectsPromotes growth rate and feed efficiency in steers and heifersSynovex S (steers)Active agentProgesterone with estradiol benzoateSupplierSyntex animal healthGeneral effectsPromotes growth rate and feed efficiency in steersSynovex H (heifers)Active agentTestosterone with estradiol benzoateSupplierSyntex animal healthGeneral effectsPromotes growth rate and feed efficiency in heifersSynovex C (calves)Active agentEstradiol 17B and progesteroneSupplierSyntex animal healthGeneral effectsPromotes growth rate and feed efficiency in calvesCompudoseActive agentEstradiol 17BSupplierElanco Animal HealthGeneral EffectsPromotes growth rate and feed efficiency in steersMGA 200 and MGA 500-puts animal on birth controlActive agentMelengesterol acetateSupplierUpjohn CompanyGeneral effectsImproves rate of gain and feed efficiency in heifers by suppressing estrusClenbuterol, Cimaterol, Ractopamine-BadGeneral effectIncrease muscle growth and decrease fat growth, improve fait of gain and feed efficiencyDecrease meat tendernessHelps with breathing-respiration therapy for horsesSide effectsMean, damage to bones and joints, testes smallerbST,pST,oST-pig and cow industryIncrease milk production in dairy cattleincrease muscle growth and decrease fat growthimprove rate of gain and feed efficiencyANSC 107 1nd EditionLecture 15Outline of previous lecture I. Productive performanceII. Growth III. Milk productionIV. Efficiency of production V. Records


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TAMU ANSC 107 - Growth and Development

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