Animal growth and development 2 nd review Lectures 3, 9, 10, 11: Prenatal and Muscle Growth and Development
Development Principles similarity among species progressive causal and irreversible; ing complexity formation of discrete structures, to a final stable state t cellular association effects period of p competence
From: Hafez & Dyer (1969) Animal Growth and Nutrition, p. 23. Lea & Febiger, Philadelphia a.
From: Gerrard, DE & Grant, AL 2003. Principles of Animal Growth & Development. Kendall/Hunt Pub. Co., Dubuque, IA
From: Hafez & Dyer (1969) Anima Philadelphia. al Growth and Nutrition, p. 23. Lea & Febiger,
Pre-natal growth Pre-natal growth α birth weight (duh!) Factors affecting: Heredity Dam size/age Litter size Placental size Maternal nutrition/health
Skeletal muscle striated voluntary Types of muscle Smooth muscle Cardiac muscle From: Frandson, RD. 1986. Anatomy and Physiology of Farm Animals. Lea & Febiger, Philadelphia.
From: Frandson, RD. 1986. Anatomy and Physiology of Farm Animals. Lea & Febiger, Philadelphia.
From: Swatland, HJ. 1984. Structure and Function of Meat Animals. Prentice-Hall, Inc., Englewood Cliffs, NJ.
Sarcomere Fundamental unit of muscle fiber From Z line to Z line From: Swatland, HJ. 1984. Structure and Function of Meat Animals. Prentice-Hall, Inc., Englewood Cliffs, NJ.
Fiber types Based upon contraction speed and metabolic pattern Slow-twitch, oxidative (SO) AKA Type 1, β red depend upon oxidative metabolism, mitochondria fiber diameters cell size (protein:dna) slower contraction speeds ( 100 msec)
Fiber types Based upon contraction speed and metabolic pattern Fast-twitch, glycolytic (FG) AKA Type 2b, α white depend upon anaerobic (glycolytic) metabolism, mitochondria fiber diameters fast contraction speeds ( myosin ATPase); p ( y ) 7.5 msec
Fiber types Based upon contraction speed and metabolic pattern Fast-twitch, oxidative-glycolytic (FOG) AKA Type 2a, intermediate, α red both oxidative and glycolytic capacity intermediate fiber diameters fast contraction speeds
Histochemical determination of fiber types Myosin ATPase staining Acid or alkali preincubation Fast alkali-stable Slow acid-stable Proportional to twitch speed Succinate dehydrogenase (SDH) staining Proportional to mitochondrial density From: Swatland, HJ. 1984. Structure and Function of Meat Animals. Englewood Cliffs, NJ. Prentice-Hall, Inc.,
Functions of different fiber types Slow, oxidative Slow, repetitive movements, e.g. postural muscles Very resistant t to fatigue Fast, glycolytic Rapid movements, heavy force generation Easily fatigued; can go into O 2 debt for short periods Fast, oxidative-glycolytic Adapted for rapid, repetitive movements Recruited after SO fibers Intermediate fatigue; recover faster than FG fibers Also: tonic muscle fibers (unusual) Multiply l innervated Graded response to stimulation frequency (vs. propagated action potential) Efficient isometric tension (e.g., anterior latissimus dorsi, holds wings against body)
From: McLachlan, J and Wolpert, L. 1980. The spatial pattern of muscle development in chick limb. In: Goldspink, DF (Ed.) Development and Specialization of Skeletal Muscle. Cambridge University Press, Cambridge.
Cellular differentiation Pre-myoblasts myoblasts myotubes 1 myofibers Late-arriving unfused myoblasts 2 myotubes 2 myofibers
Myoblast fusion is a terminal differentiation step; myotubes can no longer divide (i.e. cells leave the cell cycle):
From: Swatland, HJ. 1984. Structure and Function of Meat Animals. Prentice-Hall, Inc., Englewood Cliffs, NJ.
From: Swatland, HJ. 1984. Structure and Function of Meat Animals. Prentice-Hall, Inc., Englewood Cliffs, NJ.
From: Swatland, HJ. 1984. Structure and Function of Meat Animals. Prentice-Hall, Inc., Englewood Cliffs, NJ.
Prenatal expression of MRFs in the mouse Day Somite Limb bud 7 8 Myf-5 9 " myogenin 10 " " MRF-4 Myf-5 11 " " " " myogenin MyoD 12 " " " " " 13 " " " " 14 " " " " 15 " " " 16 " MRF-4 " " MRF-4 17 " " " " " 18 " " " " " 19 " " " " " 20 " " " " " 21 " " " " "
Physiological differentiation 1. Growing nerves invade developing muscle; multiple nerves contact each fiber, each nerve contacts many fibers 2. By birth, only one nerve contacts each fiber; each nerve contacts many fibers 3. Motor unit = set of fibers innervated by a single nerve 4. All fibers within a motor unit are of the same type
From: Goldspink, G. 1980. Growth of muscle. In: Goldspink, DF (Ed.) Development and Specialization of Skeletal Muscle. Cambridge University Press, Cambridge.
The number of muscle fibers is set prior to birth (around the end of the second trimester; Therefore, post-natal muscle growth involves increases in length and girth of existing muscle fibers.
The number of muscle fibers is set prior to birth (around the end of the second trimester; Therefore, post-natal muscle growth involves increases in length and girth of existing muscle fibers.
Sex Males have more muscle (70 vs. 64% of carcass wt) and less fat (11 vs. 16%) than females BUT: Distribution of carcass muscle, fat and bone in cattle (% of carcass wt) Tissue Forequarter Hindquarter F M F M Muscle 30.8 36.4 33.2 33.4 Fat 8.9 5.8 7.5 4.8 Bone 9.8 9.8 7.9 7.9 SO Th d t (f t i ld) i i th l SO: The advantage (for meat yield) is in the lowervalue forequarter, i.e., neck & shoulders.
Hormonal control of muscle development and growth IGF-I, IGF-II proliferation differentiation Basic FGF, TGF-β proliferation differentiation GH no direct effects?
Genetics Species and breeds vary in muscularity Muscle distribution relatively constant among cattle breeds Exceptions exist, e.g. athletes, double-muscled cattle, callipyge sheep
From: Lawrence, TLJ and Fowler, VR. 1997. Growth of Farm Animals. CAB International, New York.
From: Goldspink, G. 1980. Growth of muscle. In: Goldspink, DF (Ed.) Development and Specialization of Skeletal Muscle. Cambridge University Press, Cambridge.
From: Goldspink, DF. 1980. Physiological factors influencing protein turnover and muscle growth. In: Goldspink, DF (Ed.) Development and Specialization of Skeletal Muscle. Cambridge University Press, Cambridge.
Source: Hill et al., 2004. Animal Physiology, Sinauer Associates, Sunderland, MA.
Animal experiments Human experiments From: Goldspink, G. 1980. Growth of muscle. In: Goldspink, DF (Ed.) Development and Specialization of Skeletal Muscle. Cambridge University Press, Cambridge.
Source: Hill et al., 2004. Animal Physiology, Sinauer Associates, Sunderland, MA.