Postnatal growth & development

Question 1

Define growth…

Answer 1

progressive increase in the size (volume,

length, height, teeth or girth) or weight of animal over time

Question 2

Define development…

Answer 2

progressive changes that take place with time in the behavior of the organism
Growth
Capability
Maturation
Interaction with the environment
Development is a continuous process from birth to death

Question 3

Define isometric growth…eg…

Answer 3

growth of all tissues occurs at the same rate (‘iso’ = ‘same’)
Eg. Some reptiles have isometric growth in that their tail and body grow in equal proportions

Question 4

Define allometric growth…eg…

Answer 4

growth of tissues occurs at different rates relative to each other.
Eg. Muscle develops faster than fat deposits early in life. Once muscle is developed, then fat accelerates faster. Each tissue has fast growth phase- call growth spurt.

Question 5

Length of gestation in chicken eggs & rodents?

Answer 5

21 days

Question 6

What is AGA?

Answer 6

AGA - Appropriate for gestational age

Question 7

Example of 2 species and their AGA…

Answer 7

swine: 1kg (easy to remember)

chicken egg: 70g

Question 8

What is LGA? eg. of what this can lead to…

Answer 8

LGA - Large for gestational age where weight is above the 90th percentile at gestational age.
e.g. gestational diabetes

Question 9

What is SGA? eg. of what this can lead to…

Answer 9

SGA - Small for gestational age where weight is below the 10th percentile at gestational age.
eg. Intrauterine growth restriction (IUGR)

Question 10

What are the 3 factors controlling animal growth?

Answer 10

• genetic background
• nutritional intake
• environment

Question 11

Genetic background as a factor…

Answer 11

• Optimal growth, production & health is dependent upon good genetic qualities reflected within phenotype of animal
• Endocrine system hormones are all influenced by genetics, nutrition & environment via growth factors (GF) & growth hormones (GH) -> somatotropin axis
• nutrition & disease influence whether animal will reach genetic potential for size
• growth differences dictated by genotype eg. chihuahua vs doberman (any 2 dog/animal breeds really)
• growth differences also dictated by selection/domestication
• epigenetic factors
• growth curve depends on species, breed, gender

Question 12

Nutrition as a factor… (easy - just think fats, lipids, carbs & minerals & vitamins)
Give a couple egs for each

Answer 12

PROTEIN - building blocks for bones, muscles, cartilage etc.
LIPID - phospholipids, cholesterol (Chol-); low density lipoprotein (LDL) which is ‘bad’ cholesterol and contributes to the narrowing & silting up of the arteries, which can lead to heart disease and stroke. high density lipoprotein (HDL) cholesterol
CARBOHYDRATES - simple sugars: glucose, energy requirements oligosaccharides & polysaccharides
MINERALS & VITAMINS
- Ca, Mg, vit D: bone & tooth
- Vit A: osteoblasts & osteoclasts
- Vit B: DNA formation
- Vit C: collagen
- Zinc: biochemical reactions & immune system

Question 13

Environmental factors…

Answer 13

STRESS: can suppress immune function via HPA axis
FACILITIES: species dependent
TEMPERATURE: eg. some reptiles -> above 30 degrees affect growth rate or sex
MICROORGANISMS: bacteria, virus, parasites
TOXICANTS & POLLUTION: reduce overall health