Growth,Development and Composition

An S 426

Growth and Development – Composition

Function of genotype and environment– Cattle have 30 pairs of chromosomes

Sex determines the development and function of the organs and glands

Example:

Glands produce hormones which cause certain

things to occur in the body – some seen and others

unseenExamples:

Growth and Development Frame size is a convenient way of

– describing skeletal size within age of cattle and under normal feeding

Frame size– related to the live weight at which a

feeder animal will reach a constant level of fatness

– Basis for management decisions

Sigmoid prenatal and postnatal growth patterns

Growth Curve (postnatal)

Time

Wt. 1

2

3 4

1. Prenatal2. Rapid Growth3. Fat deposit begins4. Fat

pubertymarket

Johnson, 1997

Impacts of frame size –Large Small

Item Implant No implant

Implant No implant

1-64 day(Period 1)

Initial wt, lb End wt, lb DFI, lb DM ADG, lb F/G, lb

68494820.03.13

(+0.7%)6.39

69395519.73.116.33

65291018.43.07

(+20.7%)5.98

(+18.3%)

66087318.62.547.32

65-169 day(Period 2)

End wt, lb DFI, lb DM ADG, lb F/G, lb

117323.72.66

(+5.6%)8.95

116922.62.528.98

118820.92.09

(+16.2%)10.04

(+7.8%)

102619.61.0810.90

Impacts of frame size –Large Small

Item Implant No implant

Implant

No implant

170-267 day(Period 3)

End wt, lb DFI, lb DM ADG, lb F/G, lb

145125.6

2.84(+12.5%)

9.08(+ 3.1%)

141623.72.459.37

Impacts of frame size –Large Small

Item Implant No implant

Implant No implant

Total feeding period

End wt, lb DFI, lb DM ADG, lb F/G, lbDPBF, inLEA, sq in QG

145123.22.87

(+6.2%)8.0963.10.5313.53

C

141622.12.708.1562.80.5713.00

C

108819.72.58

(+18.8%)7.63

(+13.3%)64.50.8911.23

C

102619.12.178.8065.20.91

10.97C

Growth and Development – Composition

Results:1. Later maturity of large framed cattle

Period 1 – no difference between types for ADG and F/GPeriod 2 – small framed cattle gained slower and were less

efficientPeriod 3 – large framed cattle became less efficient

2. Large type cattle had higher DFI and ADG (P < 0.01)– F/G over total feeding period nearly the same

Growth and Development – Composition

Results:3. Implants improved ADG (P < 0.01); 44 lb. in large

and 70 lb in small framed cattle

– F/G was improved + 13.3% in small type cattle, but no difference in large type cattle

Growth and Development – Composition

Results:4. Large frame cattle had less BF and larger LEA;

when adjusted for carcass weight, small type had larger LEA (P < 0.01)

5. Small framed cattle appear to respond more to implants than large framed cattle

Growth and Development – Composition

Endocrinology –Interrelationships of small, medium and largeframe cattle and estradiol implants

Study:

Assumptions:1.2.

Treatment Insulin Growth hormone

mg / mlSmall Implant

No implant

Medium Implant

No implant

1.85

(1.96)2.06

1.32

(1.34)1.36

3.2 (2.8)

2.4

3.7

(3.1)2.5Large Implant

No implant

All cattle Implant No implant

1.43(1.23)

1.02

1.531.48

6.0(5.4)

4.8

4.33.2

Growth and Development – Composition

Results:1. Small frame, earlier maturing cattle, had higher

concentrations of insulin (P < 0.05) and lower concentrations of GH

2. Large frame, later maturing cattle, had higher concentrations of GH (P < 0.10) and lower concentrations of insulin

3. Within each cattle type, implanted cattle had higher concentrations of GH

Growth and Development – Composition

Results:4. Thus, higher insulin concentrations in small, early

maturity types of cattle may explain earlier fat deposition

Whereas, the greater concentrations of GH in large, later maturing types of cattle may account for the greater growth rate and later fat deposition

Postnatal growth curves of bone, muscle and fat

Fat distribution in carcass Commonly suggested order of fat

depots– 1. Abdominal, 2. Intermuscular. 3.

Subcutaneous, 4. Intramuscular Fat deposited greater rate than

muscle later in life such that the % of intramuscular fat, is late maturing

Rate of fat accretion in intramuscular fat is not late maturing

Back fat and marbling regressed against carcass wt

Fat distribution in carcass

1. Internal (KPH) =2. Subcutaneous (Back Fat)=2. Intermuscular =3. Intramuscular (Marbling)=

Sex hormones

The distribution of fat within beef carcasses is be similar for both sexes

Bulls generally produce leaner carcasses than steers

the deposition of fat tends to occur at a lighter weight in heifers than in steers, and at a lighter weight in steers than in bulls.