Lecture 5: Impact Of Genetic Selection On Production Systems

Question 1

What to focus on when selecting for layers vs broilers?

Answer 1

Layers: focus on egg production (number size quality)
Broilers: meat production (growth rate muscle mass)

Question 2

How have layers been impacted by genetic selection?

Answer 2

• selection focused on increasing number of eggs/cycle
• earlier sexual maturation
• extended laying cycle
• egg quality and uniformity, good shell quality

Question 3

How was genetic selection achieved in layers?

Answer 3

• earlier age at first egg - linked to growth of pullets
• metabolic threshold
• extended cycle

Question 4

What are the problems with genetic selection with layers?

Answer 4

• when pullet reaches sexual maturity - she changes her entire physiology - puts birds at risk of problems - cage layer fatigue (calcium deficiency)

Question 5

What is cage layer fatigue?

Answer 5

Calcium deficiency in layers, not enough calcium to make muscles work, can lead to osteoporosis, need calcium supplements, once this happens, its detrimental

Question 6

How has housing impacted genetic selection?

Answer 6

• layers were selected for cage production, and aviaries caused many health and behaviour problems (unfit for environment) - increase aggression
• often pullet are reared in an environment different from adult housing and cannot adapt

Question 7

How have broiler breeders been impacted by genetic selection?

Answer 7

• fast growth - not all parts grow at the same rate
• poor reproductive performance
• growing causes leg problems and mortality
• lack of proper hierarchical development of follicles leads to ovarian cysts

Question 8

What happens if you play with growth trajectory?

Answer 8

impact entry lay

Question 9

What happens to broiler breeders when they have male aggression?

Answer 9

When they grow too fast they are still too young to mate, however due to their fast growth, they are forced to. But since they are still too young they ma bye unfit for mating and instead aggress females leading to sever injuries. The problem is mostly genetic.

Question 10

Fast muscle growth in broilers can result in…?

Answer 10

Body too heavy for legs, lameness. Cardiovascular and respiratory system issues, heart attacks

Question 11

How has genetic selection impacted turkeys?

Answer 11

• genetic growth packed in male lines
• poor reproductive capacity
• hens still express incubation behaviour
• Tom: 30 kg
• Hen: 13 kg

Question 12

What to do if there is issues in your flock?

Answer 12

• management guide comes with every bird, use it?: environment (temp), diet composition and feed allocation, health and management