3/26/2009 ANS 123. Animal Science 123. Spring Silas S.O. Hung. Dept. of Animal Science 2139 Meyer Hall.

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1 Animal Science 123 Animal Growth & Development Silas S.O. Hung Spring 2009 ANS 123 Silas S.O. Hung Dept. of Animal Science 2139 Meyer Hall Office hours MW 10:00 11:00 or by appointment ANS 123 discussions Section Day Time Room TA 1 Monday 11: Chris H 2 Monday 13: Juliann S 3 Tuesday 08: Juliann S 4 Tuesday 17: Chris H 5 Wednesday 11: Alison G 6 Wednesday 17: Alison G 7 Thursday 10: Chris H 8 Friday 11: Alison G 1

2 Course objectives: At the conclusion of this course, students should understand: whole-animal growth curves & allometry genetic control of growth; importance of mature size & scaling pre-natal development at the organ, cell & molecular level for major tissues (i.e. bone, muscle & adipose) effects of environment and nutrition on growth and body composition metabolic processes important in growth, body composition and nutrient partitioning endocrine factors controlling development and growth strategies for manipulation of growth how predictive models of growth are used in definition of feeding standards for domestic livestock & other species Assessment: Grading will be based upon discussion assignments and participation (15%), two mid-term examinations (25% each) and a final examination (35%, comprehensive). Discussions: Each week, there will be a discussion session devoted to a) discussion of research papers, or b) discussion of a case study involving some aspect of disturbed growth. For weeks with research paper discussions, read the assigned paper ahead of time, bring and turn in a short (1/2 to 1 page) review, and come prepared to discuss. In your review, address the following points: purpose of the paper, methods used, experimental design, quality of data, conclusions (are they supported by the data?). For case studies, a case report will be due the following week. Text: No required text; handouts and material to be provided. I do highly recommend the following book: Gerrard, David E. and Grant, Alan L Principles of Animal Growth & Development. Kendall/Hunt Publishing Co., Dubuque, IA. Final examination (cumulative) on Wednesday, June 11 at 13:00-15:00 in 179 Chem 2

3 Tentative schedule Date Topic 1 March 30 Introduction: growth, development, differentiation. Growth curves, allometry. 2 April 1 Studying growth: methodology. 2 3 Studying growth: methodology. 3 " 6 Pre-natal growth -- general. Differentiation, morphogenesis, organ systems. Hyperplasia & hypertrophy. 4 " 8 Major hormones influencing growth; endocrine, paracrine, autocrine mechanisms; intracellular signalling pathways. 5 " 10 Major hormones influencing growth; somatotropic axis. " 13 Major hormones influencing growth; somatotropic axis 6 " 15 Development and growth of bone -- introduction. Definition of terms and cell types. 7 " 17 Development and growth of bone -- Endochondral and intramembranous bone. 8 " 20 Development and growth of bone -- pre- and post-natal; hormonal regulation. Tentative schedule Date Topic " 22 MIDTERM EXAMINATION I (lectures 1 through 8) 9 " 24 Structure and function of skeletal muscle. Histology, fiber types, contraction. 10 " 27 Development and growth of skeletal muscle prenatal; cellular and physiological differentiation 11 " 29 Development and growth of skeletal muscle -- post-natal; addition of sarcomeres and fiber hypertrophy; h satellite cells; effects of genotype, sex, exercise 12 May 1 Structure and function of adipose tissue 13 " 4 Development and growth of adipose tissue; cell number and size. More functions of adipose 14 " 6 Metabolic processes important in growth: carbohydrate and lipid metabolism; nutrient partitioning 15 " 8 Metabolic processes important in growth: nutrient partitioning; protein synthesis and degradation " 11 MIDTERM EXAMINATION II (lectures 9 through 15) Tentative schedule Date Topic 16 " 13 Post-natal growth; effects of sex and environment " 15 Post-natal growth; effects of sex and environment 17 " 18 Post-natal growth; effects of nutrition 17 " 20 Post-natal growth; effects of nutrition 17 " 22 Post-natal growth; compensatory growth May 25 HOLIDAY: Memorial Day 18 " 27 Regulation of feed intake 19 " 29 Interactions among health status, growth and body composition 20 June 1 Manipulation of growth and body composition: genetics, nutrition, feed additives, hormones; novel techniques. 21 " 3 TBA 3

4 Tentative schedule Date Topic 23 " 30 Manipulation of growth and body composition: genetics, nutrition, feed additives, hormones; novel techniques. 24 June 1 Mathematical expressions of growth. Pre- and post-natal growth curves. Prediction of growth performance, body composition & fat distribution. Development of feeding standards. 25 " 4 TBA 26 " 6 Review & wrap-up. Weeks beginning Assignment Discussions March 30 Section organization Gao, F, Hou, XZ, and Liu, YC Effect of hormonal status and metabolic April 6 changes of restricted ewes during late pregnancy on their fetal growth and development. Science in China Series C: Life Sciences 6: Abuzzahab, MJ, Schneider, A, Goddard, A, Grigorescu, F, Lautier, C, Keller, E, Kiess, W, Klammt, J, Kratsch, J, Osgood, D, Pfaffle, R, Raile, K, Seidel, B, Smith, " 13 RJ, and Chernaushek, SD IGF-I receptor mutations resulting in intrauterine and postnatal growth retardation. The New England Journal of Medicine 349: " 20 Case study McPherron, AC, Lawler, AM and Lee, S-J Regulation of skeletal muscle " 27 mass in mice by a new TGF-β superfamily member. Nature 387:83-90 May 4 Case study Carstens, G. E., D. E. Johnson, M. A. Ellenberger and J. D. Tatum Physical " 11 and chemical components of the empty body during compensatory growth in beef steers. Journal of Animal Science 69: " 18 Case study " 25 Review June 1 Review Introduction to growth and development Animal Science 123 Animal Growth & Development R. D. Sainz Lecture 01 4

5 Growth = an increase in SIZE, i.e., Body weight Lean tissue weight Body ash Body protein Linear measures Other? Development = progressive changes in form (and function) Can growth occur without development? e.g., a spherical cell: radius = r mass = M (proportional to volume) volume = V surface area = S S = 4 π r 2 and V = (4/3) π r 3 Note that when r is doubled, so that r = 2r, then V = 8V and M = 8M and S = 4S Therefore, the ratio of surface area S to cell mass M is halved! That is, S /M = ½ S/M. This means that a spherical organism will soon run out of surface area through which to exchange with its environment (nutrients, waste products, heat) unless it changes its shape. Simple geometry dictates that a growing organism must alter its form and function, therefore growth cannot occur without development! 5

6 Aspects of animal development Cell division Differentiation* - formation of primordial cells Morphogenesis - organogenesis Continued development *Differentiation: qualitative changes in cells, resulting in formation of specialized tissues (specific events throughout development) Life stages Embryonic/fetal Suckling/infantile Juvenile/prepubertal Adolescent (puberty) Reproductive (sexually mature) Senescence (usually not applicable to meat animals) Development continues throughout life, from conception to death. Growth curves Body wt, kg Age, months 6

7 Allometric growth Muscle, kg Wt, Fat 20 Bone Carcass wt, kg Allometric growth Equation for a straight line: y = a + bx Equation for an allometric curve: y = ax b Linearized allometric equation: ln y = ln a + b ln x Tissue b Pattern Muscle Growth is proportional to whole body Fat Growth is faster than whole body Bone Growth is slower than whole body 7

8 Summary Growth cannot be simply an increase in size, but must instead be accompanied by development Development includes increasing complexity, and changes in form and function Allometric growth means that different body components grow at different rates and times 8