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Stocker Programs, Feedlot Performance and Carcass Merit. Jim Oltjen University of California, Davis April 10, 2008. UC Sierra Foothills Research & Extension Center. UC Davis Feedlot. Outline. Compensatory growth Using Davis Growth Model for performance and carcass traits

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stocker programs feedlot performance and carcass merit

Stocker Programs, Feedlot Performance and Carcass Merit

Jim Oltjen

University of California, Davis

April 10, 2008

outline
Outline
  • Compensatory growth
  • Using Davis Growth Model for performance and carcass traits
  • Growing phase feed quality effects
  • Growing phase length effects
  • Previous nutrition effects on carcass merit and maintenance
  • Physiology of growth and fat development
  • Latest Research on:
    • Patterns of marbling
    • Length of stocker phase effects on fat distribution
    • Length of stocker phase effects on rate of marbling and subQ fat gain
    • Residual feed intake relationship with maintenance requirements
  • New model to predict fat distribution
compensatory growth in beef cattle
Compensatory growth in beef cattle

From: Sainz et al., 1995

slide10

Davis Growth Model

Net energy

Ttrtrttr

Rtrttr

r

Fat (kg)

Maintenance

Protein

slide11

Davis Growth Model (Oltjen et al. 1986)

Biological processes:

Cell proliferation and hypertrophy

Homeorrhetic control

Metabolizable Energy Intake

Biological processes:

Synthesis and degradation

Heat production

Biological processes:

maintenance

Efficiency of conversion into net energy is related to both quantity and concentration of metabolizable energy in the diet

slide13
Stocker cattle’s rate of gain is linear from 2 to 3 Mcal ME/kg DM assuming cattle are fed ad libitum or have adequate available forage.
slide15

Finishing daily gain is inversely and nearly linearly related to previous growing phase performance.This hardly varied whether cattle were fed to equal body weight or fat content endpoints.

slide17

Steers fed to an equal body weight endpoint were more sensitive to previous growing phase ration energy compared to steers fed to a constant fat endpoint.

Those fed higher energy diets as calves reached acceptable carcass fatness at much lighter weights.

slide19

Finishing period performance

(growing phase MEC 1.87 Mcal/kg)

slide20

Finishing period performance

(growing phase MEC 1.87 Mcal/kg)

slide22

Steers fed to an equal body weight endpoint were more sensitive to the length of the growing period compared to a constant fat endpoint.

slide23

Calf fed’s reach carcass fatness before desirable slaughter weights, confirming previous work that medium or small frame steers require a growing period before slaughter, particularly if not implanted.

slide24

Calf fed’s reach carcass fatness before desirable slaughter weights, confirming previous work that medium or small frame steers require a growing period before slaughter, particularly if not implanted.

Conversely, if we use longer growing periods due to increased cost of grain, cattle will have to be fed to larger weights for acceptable fatness, further exacerbating the progressive trend to larger carcasses in the industry.

slide25

Intermuscular Fat

Subcutaneous Fat

Intramuscular Fat

compensatory growth in beef cattle1
Compensatory growth in beef cattle

a

a

a

b

b

a

a

a

b

b

a

ab

b

c

c

From: Sainz et al., 1995

compensatory growth in beef cattle2
Compensatory growth in beef cattle

a

a

ab

ab

b

a

ab

b

ab

b

a

ab

ab

b

b

From: Sainz et al., 1995

slide31

Compensatory gain in feedlot steers

SEM

a

b

b

Sainz et al., 1995

gain in 12 th rib fat gain bf m day in high and low growth cattle backgrounded at two me levels
Gain in 12th rib fat gain (BF. µm/day) in high and low growth cattle backgrounded at two ME levels
gain in intramuscular fat gain imf day in high and low growth cattle backgrounded at two me levels
Gain in intramuscular fat gain (IMF. %/day) in high and low growth cattle backgrounded at two ME levels
residual feed intake
Residual Feed Intake
  • More efficient steers with negative RFI ate less (12%).
  • RFI was related to maintenance energy requirements (r=0.42).
  • No ‘significant’ association with carcass traits.
  • Myofibrillar protein degradation rates were positively related to maintenance energy requirements (r=0.76), but were not related to RFI (r=-0.14).

A genetic trait related to RFI should be used in prediction models to account for differences in maintenance.

Eventually adjust for protein synthesis/degration rate differences which are explicitly represented in the Davis Growth Model.

slide50

Intermuscular Fat

Subcutaneous Fat

Intramuscular Fat

slide51

Carcass

characteristics

Davis Growth Model

12/13th

Rib fat

(mm)

Net energy

Sub

(kg)

Fat

Maintenance

IMF

(%)

Intra

(kg)

Visceral

(kg)

Protein

Inter

(kg)

KPH

(kg)

KPH

(%)

first order differential equation
First order differential equation

Example: Subcutaneous fat (S; kg)

d

dt

Where j = 1 to 4 for each fat depot

Constraint

a proportional variable is a function of dna and maximum adipocyte size
a proportional variable is a function of DNA and maximum adipocyte size

Cell number (hyperplasia) ~ DNA

Cell size (hypertrophy) ~ maximum adipocyte size

proportion of total fat e g subcutaneous s kg proportional fat variable
Proportion of total fate.g. subcutaneous (S; kg) proportional fat variable

ADSMAX – Maximum adipocyte size = 4.5 x 105 kg TG/kg DNA

Constraint

slide55

of total body fat

Proportion

Intermuscular

Subcutaneous

Visceral

Intramuscular

Days on feed

model summary
Model Summary

Good starting point for predicting

12/13th rib fat (mm), IMF (%), and KPH (%) for breed type and implant status

More data is required to develop fat depot parameters e.g. serial slaughter data. But data is scarce!

Model needs to be evaluated

slide63

Body protein

DGM

INRA

Angus-Hereford steers

Salers heifers

Charolais bulls

From: Garcia et al., 2007

slide64

Body fat

DGM

INRA

Angus-Hereford steers

Salers heifers

Charolais bulls

From: Garcia et al., 2007

weight gains in high bx and low gx growth cattle backgrounded at two me levels
Weight gains in high (BX) and low (GX) growth cattle backgrounded at two ME levels

The arrows show the beginning of the finishing phase for the BX-M (1). GX-M and BX-L (2) and GX-L (3) groups.

backgrounding effects carcass traits
Backgrounding effects: carcass traits

1 Probability of a Type 1 error

2 Standard error of the mean (n=3/group)

3 Kidney.pelvic and heart fat

4 Marbling Score: ; 3 = Small 0; 4 = Modest 0.

5 Quality Grade: 0-2=Standard; 3-5=Select; 6-8= Choice; 9-11= Prime

compensatory growth in beef cattle3
Compensatory growth in beef cattle

Fat

Protein

From: Sainz et al., 1995

compensatory growth in beef cattle4
Compensatory growth in beef cattle

CL-CA

From: Sainz et al., 1995

compensatory growth in beef cattle5
Compensatory growth in beef cattle

Slight = 7-9, Small = 10-12

From: Sainz et al., 1995

slide72

Backfat, mm

Growing MEC, Mcal/kg

BW 1.87 3.06 3.06 limited MEI

237 1.0 1.0 1.0

327 2.0 6.1 3.3

481 9.9 12.6 11.6

Growing phase to 327 kg BW

slide73

Marbling Score1

Growing MEC, Mcal/kg

BW 1.87 3.06 3.06 limited MEI

237 0.9 0.9 0.9

327 2.6 5.2 3.7

481 8.7 8.0 8.9

10, devoid; 1, practically devoid0; 2, practically devoid50 3, practically devoid100; 4, traces0; 5, traces50; 6, traces100; 7, slight0; 8, slight50; 9, slight100

Growing phase to 327 kg BW

slide74

What about limit feeding concentrate in growing period?

    • Table 1. Growth performance of finishing steers previously fed a forage diet (1.87 Mcal ME/kg DM) ad libitum (FA) or a high concentrate diet (3.06 Mcal ME/kg DM) at intake levels (CL) to achieve similar growing phase gains (Sainz et al., 1995).
    • CL FA
  • ------------------------------------------------------------------------------------------------------------------
    • Period length, d 89 111
    • Intake, kg DM/d 10.98 11.73
    • Gain, kg/d 2.01 1.82
    • Feed/Gain 5.47 6.45
    • Viscera, kg 28.8 32.8
    • Relative maintenance BW-.75 .83 1.21
    • Residual feed intake, kg/d -.63 1.05
  • ------------------------------------------------------------------------------------------------------------------
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