ANSC 107 1nd Edition Lecture 15 Outline of previous lecture I Productive performance II Growth III Milk production IV Efficiency of production V Records VI Improvement VII Traits Outline of current lecture I Growth II Hormones a Endogenous peptide b Endogenous steroid c Anabolic steroids Learning objectives Understand the difference between growth and maturity To be able to identify the order of growth and the order of fat deposition Understand how hormones affect growth in livestock These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Growth Increase in body weight until maturity is reached Increase in animal tissue muscle fat and bone Measures of growth include weight unit time WDT height unit time average daily gain days to 260 swine weaning weight yearling weight True Growth The only growth that involves an increase in structural tissues Excludes fat as storage tissue Development Directive coordination of all diverse processes until maturity is reached Involves growth cellular differentiations and changes in body shape Controlled by genetic make up of the animal Maturity State of being fully grown or developed Sexual and compositional maturity Physiological vs chronological age Chronological age refers to the animals age in terms of units of time Physiological age refers to stages landmarks of development as the animal grows from conception to maturity Hyperplasia vs hypertrophy Hyperplasia increase in number of cells Hypertrophy increase in cell size Efficiency of growth Efficiency in production is defined as units of input per unit output Unit of feed lbs or kg per unit of gain lbs or kg Feed conversion values are typically 7 1 for cattle 4 6 1 for sheep 3 1 2 1 for swine 2 1 for broilers 1 1 1 for fish Growth curve is curvilinear Curved line function Growth considered an increase in body weight so most early growth follows a straight line True growth is defined as increase in body protein true growth stops when animal reaches maturity Order of tissue development At birth various body parts have different shapes and properties o For example Horse head and legs Lamb legs Order of Fat deposit Perinephric internal kidney pelvic and heart fat leaf fat Intermuscular fat seam fat Subcutaneous external fat back fat Intramuscular marbling flank streaking Early vs Late maturing Bases of USDA feeder cattle grades Large frame feed more Measures of growth in livestock Beef cattle birth weight weaning weight yearling weight feedlot AGD mature weight Sheep birth weight 60 day weight 90 day weight yearling weight feedlot AGD mature weight Measures of growth in livestock Swine birth weight weaning weight days to 23 lbs Horses growth is generally measured in hands at a certain age Poultry days to slaughter weight Correlated responses to selection for growth Selection for growth can influence other traits as well Some traits are influenced positively while others are influenced negatively Genetic effects on growth and development Growth is moderately to height heritable trait h2 ranking from 3 5 Body Carcass composition Environmental effects of growth and development Hormonal control of Growth What is a hormone Chemical substance that is secreted into the boy fluids by one cell or group of cells and has an effect on other cells Control of body o Nervous and hormonal Endogenous peptide hormones Hormone o Growth hormone GH somatotropin bsT oST pST Source o Anterior pituitary AP General effects o Increased growth rate o Increased muscle to bone o Increased mature size o Decreased fat o Increase milk production Endogenous Peptide Hormones Somatostatin turns growth hormone off o Source Hypothalamus o General effects Inhibits release of GH from AP Thyroxine o Source Thyroid o General effects Promotes energy production and oxygen consumption by peripheral tissue helps you grow and keeps you warm Insulin o source pancreas o general effects stimulates growth by increasing the uptake of glucose and amino acids by peripheral tissues Increase the synthesis of RHA which leads to protein synthesis Epinephrine o Source Adrenal medulla o General effects Regulation of cardiovascular system Increased heart rate Mobilizes glycogen from liver Mobilizes leg muscle receptors Dilates pupils Norepinephrine o Source Adrenal medulla o General effects Stimulates brain function Regulation of cardiovascular system Decrease heart rate Glucocorticoids o Source Adrenal cortex o General effects Affects carbohydrates metabolism and have power anti inflammatory actions as well as adverse side effects Increase food intake Endogenous steroid hormones Testosterone o Source Testes o General effects Increase growth rate and feed efficiency Increased mature size Increased muscle and bone Decreased fat Slows skeletal growth Associated with onset of puberty Estrogen o Source Ovaries o General effects Slows skeletal growth However exogenous estrogenic compounds promote growth rate and feed efficiency in steers Cortisol o Stress hormone o Increase immune system Progesterone pregnancy hormone o Source Corpus Luteum o General effects Exogenous progestogenic compounds promote growth rate and feed efficiency Anabolic Steroids Diethylstilbestrol DES o Active agent Estrogen o Supplier Banned by FDA causes human birth defects o General effects Promotes growth rate and feed efficiency in steers and heifers Synovex S steers o Active agent Progesterone with estradiol benzoate o Supplier Syntex animal health o General effects Promotes growth rate and feed efficiency in steers Synovex H heifers o Active agent Testosterone with estradiol benzoate o Supplier Syntex animal health o General effects Promotes growth rate and feed efficiency in heifers Synovex C calves o Active agent Estradiol 17B and progesterone o Supplier Syntex animal health o General effects Promotes growth rate and feed efficiency in calves Compudose o Active agent Estradiol 17B o Supplier Elanco Animal Health o General Effects Promotes growth rate and feed efficiency in steers MGA 200 and MGA 500 puts animal on birth control o Active agent Melengesterol acetate o Supplier Upjohn Company o General effects Improves rate of gain and feed efficiency in heifers by suppressing estrus Clenbuterol Cimaterol Ractopamine Bad o General effect Increase muscle growth and decrease fat growth improve fait of gain and feed efficiency Decrease meat tenderness Helps with breathing respiration