2A. Reproduction

Question 1

What is the decision to mate based on?

Answer 1

• Whether an animal has desirable trait they can pass on
• Usually has economic value

Question 2

Traits of economic importance

Answer 2

1. Fertility
2. Rate and efficiency of body weight gain
3. Milk production
4. Egg production
5. Birthing ease

Question 3

Types of animal breeders

Answer 3

1. Seed-stock
2. Commercial

Question 4

What are seed-stock breeders?

Answer 4

PUREBREDS where ancestry is recorded on pedigree by breed association

Question 5

What are commercial breeders?

Answer 5

COMMERCIAL slaughter livestock are crossbred

Question 6

Where do replacement stock come from?

Answer 6

• Only the best animals from a breed are chosen to provide new stock (part of purebred groups with records that help calculate their breeding value)
• They are ranked based on their genetics.
• The top-ranked animals are picked as replacements to continue breeding.

Question 7

Top tier vs bottom tier

Answer 7

Top tier - most genetically pure
Bottom tier - breeding animals at commercial farm level

Question 8

What is heterosis/hybrid vigour

Answer 8

Performance of progeny exceeds that of either parent

Question 9

What is a nucleus

Answer 9

• Single/group of herds that breed their own male and female replacements
• Can import individuals from another nucleus

Question 10

What are multipliers?

Answer 10

• Some individuals from a nucleus and they produce breed stock to satisfy the demand from commercial tier

Question 11

What is the commercial level

Answer 11

All breeding stock to produce animals for market

Question 12

Breeding structure in swine/poultry

Answer 12

1. Nucleus: breeding companies with elite lines that are property of the company
2. Multiplier: own by breeding companies
3. Commercial production: stock from breeding companies for commercial farmer companies

Question 13

Example of poultry pyramid

Answer 13

Question 14

Answer 14

Question 15

Answer 15

Question 16

Dairy cattle pyramid

Answer 16

Question 17

Beef cattle pyramid

Answer 17

Question 18

Types of mating systems

Answer 18

1. Inbreeding
2. Line-breeding
3. Crossbreeding

Question 19

What is inbreeding?

Answer 19

• Mating closely related animals for several generations
• Increases homozygosity

Question 20

What are advantages/disadvantages of inbreeding?

Answer 20

A: Quickly identifies desirable traits

D:
- Detrimental to reproductive performance, pre-weaning, post-weaning
- Reduce the rate of genetic gain

Question 21

What is line-breeding?

Answer 21

• Low risk of inbreeding that maintains genetics from ancestor
• Level of homozygosity is lower than inbreeding because they’re not genetically pure

Question 22

What kind of producers should use line-breeding and why?

Answer 22

• Seed-stock
• High level of genetic superiority in their herds and find it difficult to locate sires that are superior to the ones in their herd

Question 23

What is crossbreeding?

Answer 23

• Animals that are not closely related are mated
• Including different breeds or lines or strains

Question 24

What are the advantages/disadvantages of cross-breeding?

Answer 24

A: breed complementarity, more heterosis (hybrid vigour)