Growth and Development Flashcards
Growth and Development
-Growth=increase in body weight until mature size is reached
-Growth and development divided into 2 phases= prenatal + and postnatal
Prenatal Growth
-development of tissues, organs, skeletal system, ect
-prenatal muscle growth primarily hyperplasia
Hyperplasia and Hypertrophy
-Hyperplasia=increase fiber number
-Hypertrophy=increase fiber size
How does growth occur?
-postnatal muscle growth primarily hypertrophy
-accretion=growth or enlargement by gradual buildup
-measuring growth=average daily gain (ADG), end weight-start weight / days between weights
-weight per day of age (WDA), animal weight/days of age
Growth Curves
-sigmoid shape=x-axis, y-axis
-maturity reached when curve flattens
-generally, steeper curve=more profitable
Different tissues accumulate at different rates
-muscle=fastest early in life, deposition through maturity
-bone=decreasing rate, most complete by puberty
-fat=fastest near maturity
Fat
-Intra-abdominal fat=deposited in abdominal
-Subcutaneous fat- deposited under skin; back fat
-Intermuscular fat= fat between muscles
-Intramuscular fat= fat within muscles; marbling
Bone Mammal
-long=epiphyseal plate
-short
-flat
Bone Avian
-Pneumatic
-Medullary
Sex Differences
Fat
-females > castrated male > uncastrated male
Weight
-uncastrated > castrated > female
Exception: pigs
-castrated male fattest
-female heavier than castrated male
Compensatory Growth
-increased growth rates after a period of stress of nutrient restriction
-“catch up growth”
-Often results in= similar body weights to animals not stressed and extended growth period
Why does Compensatory growth happen?
-lower metabolism?
-more efficient feed use
-unclear
Nutrient Partitioning
-tissues receive nutrients based on the importance of their contribution to the animal
-System
1.nervous
2.circulatory
3.respiratory
4.digestive
5.reproductive
-Tissues
1.skeletal
2.muscle
3.adipose
Nutrients first prioritized to maintenance
-30-40% growth
-90% mature
Remaining nutrients go towards
-growth
-finishing
-production
-work
-reproduction
Positive and Negative energy balance
-Positive energy balance=animal has enough energy to meet all needs
-Negative energy balance= nutrient intake does not meet need, weight loss
Hormone modification of growth
-Testosterone=increase muscle and bone development, castration diverts energy from muscle growth to fat
-Estrogen=increase fat deposition and mammary development
-federal law prohibits added hormones in pork and poultry production
Hormone Modification of Growth in Beef
Beef commonly implanted in feedlot
-approved and regulated by FDA
-increase growth
-improve feed efficiency
-reduces cost of meat
Implanted into ear, under skin
-why?
Very little increase of hormones in meat
-2 vs 3 ng Estrogen per 3-oz serving
-3 oz broccoli = 96,000 ng Estrogen
Beta Agonists
-Not hormones
-Cattle, pigs, turkeys, phased out in swine
-repartition nutrients toward muscle growth
-ractopamine (Optaflexx, Paylean), zilpaterol (Zilmax)
AGPs-antimicrobial growth promtants
-antibiotics used in animal feed since 1950’s= antimicrobial, growth promoting, improve efficiency, subtherapeutic
-2017=FDA disapproved use of medically important antibiotics for growth promotion
-use of these classes must be under veterinary oversight
Energy
-ATP-ADP cycle
-Liver glycogen or glucose synthesis by the liver and dietary carbohydrates turn into blood glucose
-muscle glycogen and blood glucose turn into glucose
-glucose is used by anerobic and aerobic metabolism
-dietary and body protein turn into amino acids
-adipose tissue and triglycerides in muscles turn into fatty acids
-amino acids and fatty acids are used for aerobic matebolism
Anerobic Metabolism
-Glucose
-Lower ATP yield
-Faster
-Cytoplasm
-Products: lactic acid
Aerobic Metabolism
-glucose and oxygen
greater ATP yield-more energy
-slower
cytoplasm and mitochondria
-products: CO2 and water
Low exercise intensity and energy generation
-lots of oxygen
-aerobic metabolism
High exercise intensity and energy generation
-lack of oxygen
-anaerobic metabolism
-buildup of lactic acid
Adapting to excersie
-acute adaptations=changes in physiology that occur during exercise
-chronic adaptations-change in structure and functions of the body that occur in response to regular completion of exercise
Training
-training permits adaptations that minimize the disturbance to homeostasis resulting from exercise
-allows exercise intensity to be increased for a given distance or duration, or given intensity can be sustained longer
Warm-up
-increase in respiration and heart rate
-stretch muscle
-prevent injury
Warm-down/Cool-down
-gradually reduce heart rate and blood flow
-remove waste products (lactic acid, carbon dioxide)
-return muscle to resting length
Steady-state
-longer duration
-lower intensity
-Aerobic metabolism
-slow-twitch muscle-increase muscle endurance
Interval
-shorter duration
-higher intensity
-anerobic metabolism
-fast-twitch muscle-increase size
Muscle fatigue and soreness
-when muscle ATP is depleted=muscle fatigue, muscle cramps
-fatigue also due to conduction failure (ion imbalance) and lactic acid (drop in pH) = lactic acid cleared within serval hours through Cori Cycle
-Delayed onset muscle soreness=microtears in muscles, repairs=stronger muscles
