Exam 3 - Growth (AI Flashcards)
What are the phases of whole animal growth described by sigmoidal growth curves?
Self-Accelerating Phase, Point of Inflection, Self-Inhibiting Phase, Asymptote
The sigmoidal growth curve is characterized by its ‘S’ shape.
What is the difference between Physiological age and Chronological age of an animal?
Physiological age refers to specific physical or chemical stages of maturity, while Chronological age is the age in absolute time units (days, months, years).
Physiological age can vary significantly among animals of the same species.
How do external factors alter growth patterns?
Factors such as nutrition, disease, stress, and activity level can influence growth patterns.
These factors can change the shape of the growth curve.
What are the three types of growth curves that can be calculated and plotted?
- Cumulative growth curves
- Absolute growth curves
- Relative growth curves
What did John Hammond observe about the components of growth?
He observed that body components that are physiologically more important develop first, and extremities complete their development first.
Hammond’s work laid the foundation for understanding growth proportions.
What does the formula Y = ax^b describe in Allometric growth?
Y = log weight of carcass or animal, a = constant, x = log weight of tissue or component, b = growth coefficient of tissue or component.
What does the slope ‘b’ indicate in Allometric growth?
If b > 1, tissue grows faster than the whole; if b < 1, tissue grows slower; if b = 1, tissue grows at the same rate as the whole.
This relates to the development stages of different tissues.
What is the significance of the Point of Inflection in growth curves?
It is the point of maximum growth velocity after which growth continues at a decreasing rate.
What is the Self-Accelerating Phase characterized by?
Characterized by exponential growth with each cell dividing at a constant rate.
This phase leads to rapid growth with little complexity.
What happens during the Self-Inhibiting Phase?
The animal approaches mature weight at a decreasing rate of growth, with a gradual decrease in food intake.
What is the Asymptote in growth terms?
The point at which food intake matches maintenance requirements and is regarded as mature body weight.
What defines Absolute growth?
Cumulative weight of muscle, bone, and fat over time, resembling cumulative sigmoidal growth curves.
How is Relative growth rate calculated?
RGR = (ln Y2 - ln Y1) / (t2 - t1)
ln represents the natural logarithm.
What did Hammond conclude about Allometric growth?
Allometric growth does not fully describe growth changes, as nutrition affects tissue priority during growth.
What are the main components of whole body growth?
- Muscle
- Fat
- Bone
- Organs
What does Absolute growth refer to?
Cumulative weight gain over time for muscle, bone, and fat.
What changes in tissue composition occur during growth?
Changes occur in water, protein, lipid, and ash content.
Each tissue has a different growth trajectory.
True or False: The maximum growth for each tissue occurs at the same time.
False.
Fill in the blank: The maximum growth velocity is the period of greatest average daily gain, occurring at the _______.
Point of Inflection.
What are the characteristics of Allometric growth?
It studies how body parts change in size as an animal develops, with proportional relationships between tissues and the whole body.
What are the early developing muscles identified in Allometric growth?
- Distal aspects of thoracic limbs
- Proximal thoracic and hind limb
What defines the Self-Decelerating Phase?
The rate of growth decreases as the animal approaches mature weight.
What is the relationship between growth and nutrition according to Hammond’s findings?
When nutrition is limiting, tissues have different priorities for nutrient allocation based on their developmental sequence.
What type of growth curves do weight changes of muscle, bone, and fat over time resemble?
Cumulative sigmoidal growth curves
Which tissue experiences maximum growth first?
Bone
List the order of maximum growth for each tissue.
- Bone
- Muscle
- Fat
What type of growth is compared with allometric growth curves?
Absolute growth
What are the components of bone, muscle, and fat?
- Water
- Protein
- Lipid
- Ash
What does percentage growth describe?
Muscle, bone, and fat as a percentage of the whole body
What does the total percentage of body composition add up to at any time point?
100%
How does fat change as a proportion of the body with age?
Fat becomes a larger proportion of the body with age
As age increases, what happens to the proportions of muscle and bone?
Muscle and bone make up a smaller proportion
What are the chemical components that change over time in body composition?
- Water
- Fat
- Protein
- Ash
What is the water content range of muscle?
68 to 85% of muscle
When is the water content of muscle greatest?
Early in life
What happens to the absolute and percentage protein content in muscle as age increases?
Increases
What happens to the water content of fat cells as age increases?
Decreases
When is protein content in adipose tissue greatest?
Early in life
List the order of maturity of adipose tissue depots.
- Kidney
- Mesenteric
- Subcutaneous
- Intermuscular
- Intramuscular
What happens to water content in bone as age increases?
Decreases
What happens to protein content in bone over time?
Decreases
What happens to absolute mineral content in bone as age increases?
Increases
What happens to fat content in bone with age?
Tends to increase
What happens to the absolute amount of connective tissue as age increases?
Increases
What two proteins increase significantly with muscle development?
- Collagen
- Elastin
What effect does muscle atrophy have on connective tissue percentage?
Increases the percentage of connective tissue
In the comparison of gastrocnemius muscle between young and old rats, what is immunostained?
Fibronectin
What controls growth phenotypes in animals?
Interactions between an animal’s genotype and environment
What are the genetic differences that affect growth?
Species, breed, sex, genetically modified organisms
Define heredity in the context of genetics.
The process of passing along genes from one generation to the next
What is evolution in genetics?
Results from selection of mutations that arise in genes
What does genotype refer to?
The unique set of genes that an animal possesses in its genome
What are heritability scores?
Reflect the ability of an animal to pass a particular trait to the next generation
What defines a species?
Organisms capable of interbreeding and producing fertile offspring
How does natural selection affect species evolution?
It plays an important role in the development of different species or speciation
What is the significance of muscle distribution in species?
Relative distribution of muscle has been altered by selection and/or domestication
How do muscle distribution patterns differ between wild and domesticated species?
Wild species have greater muscle in hind-legs for speed; domesticated have more abdominal muscle
What is the role of breed selection in animal growth?
Selection pressure on different traits has led to many different breeds within a species
What are large-framed and small-framed cattle?
Large-framed have larger skeletons; small-framed have smaller skeletons
How does frame score relate to cattle growth?
It is given for a particular age range to determine frame size
What is the difference between early-maturing and later-maturing cattle?
Early-maturing grow quickly; later-maturing take longer to reach mature weight
How does sex affect growth in livestock?
Intact males are generally heavier and attain compositional maturity later than females or castrates
What are the essential nutrients for growth?
Proteins, carbohydrates, fats, vitamins, minerals
What is energy balance in animal growth?
The relationship between energy intake and energy expenditure
What is compensatory growth?
Growth that occurs after a period of nutrient restriction
Why is protein important for growth?
It affects the composition of a carcass and is essential for muscle development
What is meant by protein quality?
The biological value for a protein source
What factors affect how energy is used for growth?
Age, physiological state, nutrient availability
How do microbes impact animal growth?
They can have a negative effect on growth
What strategies are used to mitigate the negative effects of microbes?
Improved nutrition, management practices, and selective breeding
True or False: Stress negatively affects growth in livestock.
True
Identify the energy sources for physical activity in livestock.
Carbohydrates and fats
Fill in the blank: The formula for phenotype is _______ + Environment.
[Genotype]
What is the relationship between milk production and muscle in dairy breeds?
Selection for muscle is inversely related to milk production
Describe the differences in growth patterns between male, female, and castrated animals.
Males are heavier, attain maturity later; females and castrates grow differently
What is the significance of frame size in cattle?
It affects growth rate and body composition at maturity
How do genetics influence carcass composition?
Different traits have varying heritability scores affecting selection
What is a Barrow?
Castrated boar
What is a Gilt?
Female pig that has not produced a litter
What is a Wether?
Castrated ram
What is a Capon?
Castrated rooster
What is a Pullet?
Young hen
Where do intact males have a greater proportion of muscle?
Forequarter, specifically in neck and thorax
What are androgen binding receptors associated with?
Increased muscle in intact males
What is the muscle distribution in females?
Increased proportion in pelvic limb and abdominal wall
How do muscle fiber diameters compare between males, castrates, and females?
Males have larger diameters than castrates and females
What hormone drives the differences in muscle size?
Testosterone
What effect does estrogen have on bone growth?
Stimulates epiphyseal plate closure
Why are intact males typically taller than females?
Long bones grow more before closure
Which hormones increase periosteal bone growth?
Estrogens and androgens
How does sex affect lipogenesis and lipolysis?
Regulated through sex steroids
What is the order of fat deposition in cattle?
Male, castrate, female
What drives nutrient partitioning in animals?
Sex effects
Why do females fatten sooner than males?
Decreased long bone growth due to increased estrogen
What essential nutrients are crucial for growth?
- Fatty acids
- Amino acids
- Carbohydrates
- Vitamins
- Minerals
What happens when nutrients are consumed in excess of maintenance requirements?
Allows for growth, production, and reproduction
What are maintenance requirements?
Maintain vital organs and bodily functions with little or no physical activity
What are growth requirements?
Body tissues growth, including muscle, bone, fat, and nerve
What are production requirements in nutrition?
- Lactation
- Wool
- Eggs
- Physical activity
- Reproductive behaviors
- Work
What is nutrient partitioning?
Utilization of nutrients among various tissues and organs according to physiological importance
What takes priority during pregnancy?
Fetus holds priority similar to vital organs of dam
What is negative nutrient partitioning?
Nutrient intake is not sufficient to meet needs
What is positive nutrient partitioning?
Nutrients are plentiful for body maintenance, growth, and fattening
What is compensatory growth?
Growth after a period of nutritional stress
What can severely restrict compensatory growth?
Severe starvation can stunt growth permanently
What influences the severity of compensatory growth?
Severity of nutrient restriction and stage of growth curve
What is the importance of dietary protein quality?
Refers to the balance and bioavailability of essential amino acids
What happens when energy intake increases beyond a certain point?
Energy is partitioned to fat instead of muscle
What is the relationship between energy required for maintenance and size?
Energy required for maintenance increases with size
What is the difference in protein requirement between sexes?
Males have higher dietary energy requirements than females
What is the role of microorganisms in animal growth?
Affect growth rates and efficiency
What can improve growth rates and feed efficiency?
Better sanitation
What is the cost of the immune response against microbes?
Takes resources away from growth
What strategies can limit the effect of microorganisms on growth?
- High biosecurity
- Nutrient-rich diets
- Vaccinations
- Antibiotic treatments
Why are antibiotics rarely used as growth promoters today?
Public concerns about antibiotic resistance
How does physical and social stress affect growth?
Affects the hypothalmo-pituitary-adrenal axis
What is the effect of chronic stress on glucocorticoids?
Inhibits growth
What are common sources of transportation stress for animals?
- Temperature
- Novel social group
- Absence of feed and water
- Motion
How does housing stress arise?
Introduces new animals into a new social order
What is the effect of chronic stress on growth in animals?
Elevated circulating concentrations of glucocorticoids inhibit growth
Chronic stress can lead to various physiological changes that negatively impact growth.
What factors contribute to transportation stress in animals?
Temperature, wind, novel social group, absence of feed and water, motions
Transportation stress can affect the well-being and growth of animals during transit.
What is housing stress in animals?
Associated with introducing new animals into a new social order, requiring establishment of a new social hierarchy
Housing stress can lead to aggression and injuries among animals.
How can housing stress be reduced for animals?
Rearing animals in a group from weaning to slaughter (Specific-Stress-Free, SSF housing)
This method results in reduced injuries and improved growth.
Define physical activity.
Any body movement that works your muscles and requires more energy than resting
Physical activity is critical for overall health and growth.
What is the caloric expenditure for walking at 4.0 miles/hr?
8.2 kcal/min
Different activities have varying levels of caloric expenditure.
What are the available energy reserves in the body for physical activity?
ATP in muscle, muscle and liver glycogen converted to glucose, complete oxidation of glucose and fatty acids
These reserves enable sustained physical activity.
How does resistance exercise affect muscle protein synthesis?
Increases muscle protein synthesis
Resistance training is important for muscle growth.
What effect does endurance exercise have on protein synthesis?
May actually decrease synthesis if insufficient dietary energy and protein is available
Endurance training does not promote muscle growth like resistance training.
How does physical activity impact bone mass?
Increased activity during development increases bone mass, density, and size
Exercise is crucial for skeletal health.
What is the impact of exercise before maturity on peak bone mass?
Increases peak bone mass
Developing bones benefit significantly from physical activity.
What role does fat play in physical activity?
Provides a vital energy substrate, especially for aerobic exercise
Fat is an essential energy source during prolonged activities.
What hormones are released during exercise?
Growth hormone (GH) and IGF-1
Both hormones are important for growth and metabolic processes.
How does exercise intensity affect GH release?
The amount of GH released depends on exercise intensity
Higher intensity exercise typically results in greater GH release.
What happens to GH release with exercise after middle age?
Induces much less GH
Aging is associated with a decline in GH response to exercise.
Which sex matures earliest among intact animals?
Intact females
Maturity can vary significantly among different sex classes.
What is the exception regarding maturity in pigs?
Gilts mature later and reach heavier weights than barrows
This phenomenon may be linked to hormonal differences.
What influence does estrogen have on gilts compared to barrows?
May enhance muscle development
Hormonal factors can affect growth rates and body composition.
