Food Animal - Body Composition & Growth Promotion

Question 1

What is a vet’s role in meat production?

Answer 1

Breeding advice
Procedures (eg castration)
Production system & nutrition
Optimising slaughter weight /age
Manipulations (eg growth promotion)

Question 2

What factors influence composition of meat animals?

Answer 2

Breeds/genotypes
Sex status
Feeding/nutrition
Slaughter at optimum weight
Growth promotion

Question 3

What are the slaughter ages for different meat animal species?

Answer 3

Pigs = 6 months
Sheep = 5 months - 1+ year
Cattle = 10 months - 3 years (30 months)
Broiler chicken = 42 days

Question 4

What can be a consequence of breeding a large sire breed to a small dam?

Answer 4

Dystocia (difficult birth)

Question 5

How does bone/muscle/fat composition compare in young & old animals?

Answer 5

Young = high bone, low muscle, low fat
Old = low bone, high muscle, very high fat

Question 6

What are the 2 types of maturation in cattle?

Answer 6

Early maturing - put fat on quicker (need sufficient nutrients), but are less heavy (native breeds)
Late maturing - take longer to reach 15-20% fat targeet. but kill out heavier (continental breeds)

Question 7

What does ‘maturing’ mean in terms of composition & development/growth?

Answer 7

“The likelihood of putting on fat with increasing Energy Density of Diet”

Question 8

What effect do sex steroids have on maturation in cattle?

Answer 8

Heifers mature earlier than steers, which mature early than bulls
oestrogen vs testosterone

Question 9

What is the ideal beef carcass classification?

Answer 9

4LR

Question 10

What does the final live weight determine?

Answer 10

Optimum tissues composition & carcass weight
Affects price of carcass

Question 11

What is allometry?

Answer 11

The relationship of the growth of one part of an organism to the growth of another part/the growth of the whole organism

Question 12

What does it mean when the allometric growth coefficient (b) of one part of the animal is <1?

Answer 12

The part is growing slower than the whole body - better cuts of meat

Question 13

What does it mean when the allometric growth coefficient (b) of one part of the animal is =1?

Answer 13

The part is growing at the same rate as the whole body

Question 14

What does it mean when the allometric growth coefficient (b) of one part of the animal is >1?

Answer 14

The part is growing faster than the whole body

Question 15

How does body composition compare between bulls, steers & heifers?

Answer 15

Bulls heavier, leaner & less fatty than steers
Steers heavier, leaner & less fatty than heifers

Question 16

What is the feed conversion ration (FCR)?

Answer 16

=kg feed / kg weight gained

Question 17

How can marbling fat in meat be increased?

Answer 17

Feeding low protein diets in the later stages of growth (85-110kg)

Question 18

Why are growth promoters used?

Answer 18

Economic gain (meat
Clinical therapy (debilitated animals)

Question 19

What are some methods of growth promotion?

Answer 19

Selective breeding
Optimised husbandry
Alter GIT flora (diet, probiotics, antibiotics)
Affect hormone balance (eg somatotropins, sex steroids)

Question 20

What is the effect of growth promoters?

Answer 20

Change growth rate
Change feed conversion
Alter body composition

Question 21

What are some examples of growth promoters?

Answer 21

Growth hormones - bovine somatotropin (bST)
Sex hormones - oestrogens & androgens (behind the ear implant in cattle)
Catecholamines - beta-adrenergic agonists (clenbuterol)
Antimicrobials (affect gut flora)
Porcine somatotropin (PST)