Juvenile growth

Question 1

What is growth?

Answer 1

An increase in metabolically active protoplasm

Question 2

Differential cell growth is called

Answer 2

Development

Refers to the fact that not all tissues increase at the same rate

Question 3

Mammalian growth curve

Answer 3

Most mammals have a sigmoid growth curve

i.e. grow really fast then slow down and eventually cease growing

Question 4

Tissue growth of foetus order:

Answer 4

1. Central Nervous System
   - Mitotic activity completed by birth
   - Further development due to hypertrophy of existing cells
2. Skeletal System
   - Mostly in place prior to birth
3. Musculature
   - Along with but slightly delayed to bone
4. Adipose
   - Maximal growth occurs after all other systems are fully developed and animal has reached it ultimate size
   - Energy is needed for other systems before it can store energy needed to lay down fat

Question 5

Factors affecting growth

Answer 5

Genetic:

• Species
• Breed and strain
• Mother determines foetal size
• Paternal size affects postnatal growth

Environmental:

• Maternal age - young mothers are still growing so compete with foetus for resources
• Maternal size
• Maternal nutrition
• Climate stress
• Sex (males usually larger than females)
• Litter size (large litter in polytocus species compete for resources but does not reduce gestation time)

Endocrine:

• Bone growth stimulated by somatomedins i.e. insulin like growth factors
• Insulin stimulates adipogenesis
• Muscle growth stimulated by different somatomedins

Question 6

Compensatory growth

Answer 6

Animals raised in poor conditions may be small sue to limited feed intake
Catch up growth is possible if feed intake is increased prior to puberty
Effect is usually permanent if not corrected in time or deficiency occurs at a critical stage (i.e. during bone development)