Transcript Document

Growth and efficiency of
feedlot cattle
Prof Eddie Webb
Head: Dept. Animal & Wildlife Sciences
University of Pretoria
Email: [email protected]
2015 Cattleman's Conference, SA Feedlot
Association
Index
1. Why focus on growth and efficiency?
a)
b)
2.
3.
4.
5.
6.
Local demand
Options to increase meat production from gate to
plate
Animal growth and development?
Efficiency and estimates of Growth?
Does size matter?
From veld to efficient feedlot growth
Old and new technologies to improve growth
and efficiency
a)
b)
c)
d)
Growth enhancing technologies
Selection for ADG, FCR (F:G), RFI
Genomic technologies
Ultrasound scanning & Metabolic hormones
7. Options for improving feedlot performance
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1. Why focus on animal growth and
efficiency?
1. Only increase
profitability
through reductions
in input costs
2. Improving growth
and efficiency
3. Improve value of
product
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1(a).Local demand for meat
1. Beef consumption increased more than beef production
for the period from 2000-2009
2. Local beef industry needs to increase beef production by
about 11% per annum to supply the demand
3. Red meat production increased. Carcass weights
increased from 230 kg to 262kg
4. SA has capacity to increase meat production – without
changing the nature of the production systems
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1(b).Options to increase global meat
production?
1. Horizontal integration
• Deforestation
• CO2 utilization and O2 production
2. Vertical integration
• More efficient production
• Reproductive efficiency
• ADG’s, FCE’s
• Feed quality
• Strategic supplementation
• Link systems (veld, feedlot)
• Add value
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1(c).Effective growth from gate to
plate?
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2. Understanding animal growth
and efficiency is essential to
optimize production efficiency
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2(a).Characteristics of growth?
1. Growth is a quantitative phenomenon
2. Most important property
= rate of growth e.g.
1. includes the  body weight
2. and  body composition and proportions
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2(b). What is growth?
1. Growth  increase in
hyperplasia +
hypertrophy
2. Differentiation /
Development   cell
or tissue structure
and functioning

 shape and dimensions
of organs, systems,
and hence phenotype
of the organism
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Chronological vs.
physiological age
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2(c).Growth and development
• Growth and development in animals
– directly dependant on influences in the
external and internal environment
• This implies that the growth genes need to
draw on the external and internal
environment for their expression
P = G + E + iGE
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2(d).Growth process
• Growth from birth to maturity
– associated with continuous changes in body
conformation and composition,
– simulated by means of mathematical functions
and allometric relationships
• Mathematical description of growth
– polynomial of suitable degree
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2(e).Change in
conformation /
shape
(Differentiation)
Selection for growth
and efficiency
2(f).Actual vs. potential growth
1. Actual growth
– intrinsic characteristic of a given animal and
represents the realisation of its genetic
potential
– result of various internal (genetic, sex, health
etc.) and external (diet, housing etc.)
influences
2. Potential growth
– simulated in computerised simulation models
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2(g).Shape of the growth curve
• The shape of the postnatal growth curve is similar
in all species and it is the result of a concomitant
increase in bone, muscle and fat in that order.
Sigmoidal process
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3. Efficiency of growth
Birth
Birth
3(a).Parameters of Growth Efficiency
• Growth rate or gain (ADG, kg or g); Feedlot gain(kg)
• Dry matter intake (DMI)
• Feed conversion ratio or Feed to growth ratio (FCR
or F:G)
• Kleiber ratio (kg0,75)
• Residual feed intake (RFI)
– All influenced by:
•
•
•
•
mature size (protein accretion rate)
rate of maturing
fatness
time scale
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3(b).Growth hormone cascade
(somatorophic axis)
1st order hormones
2nd order hormones
3rd order hormones
4. Does Size matter?
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4(a).Normal distribution of size
(or any characteristics) in a
population
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4(b). Genetic variation?
NGUNI
Belgian blue
Bos taurus africanus
Bos taurus
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5. From veld to efficient
feedlot growth
How to optimize growth?
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5(a). Feedlot performance depends
on 3 factors:
1. Exploitation of compensatory growth (weaning
phase to inflection point)
2. Build on skeletal system – muscular growth with
optimum fattening
3. Exploitation of hypernutrition
4. Carcass dressing / dress-out%
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5(b).Growth and Tissue composition
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5(c).Nutrient priorities in the body
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Chronological vs.
physiological age
Slaughter
Fattening
Feeding
Weaning
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Changes in SA beef carcass
composition (1972 – current)
Year
19721
19842
Age
Not available
A
AB
C
A
AB
C
A
AB
B
C
%
13.7
-
-
-
17.7
17.9
20.4
17.3
18.4
18.3
21.0
Muscle %
63.5
-
-
-
67.8
64.9
64.1
72.0
65.7
64.6
62.13
Fat
22.8
14.0
16.5
16.1
15.1 17.0
16.2 11.0 16.0
17.1
16.2
Bone
%
20103
20154
*Physical composition of the whole carcass was predicted from the chemical composition of the prime rib cut
1Naudé, 1972
2Klingbiel, 1984
3Schönfeldt, Naudé & Boshoff, 2010
4Hall, 2015
5(d). Hypernutrition and selection
for growth
Nutrition
Somatotrophin
Insulin
Liver
Metabolism
N2 excretion
N2balance
Protein anabolism
Lipolysis
Hyperlipeamia
Hyperglycemia
Plasma
somatomedin
Tissue
somatomedin
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5(e).Carcass or Slaughter%
(Dressing %)
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High carcass yield
(by means of genetics, age & nutrition)
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5(f). Shifts in Animal Production
and Animal Growth
1. Emancipation of human kind, hunter gatherers to
domestication of livestock
2. Quantitative era – increasing numbers of animals
3. Quantitative era – numbers and maximum yield
4. Qualitative era – product quality
5. Consumer driven, origin, quality, safety, traceability,
sustainable and responsible systems
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6. Old and New technologies to
address the challenges?
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6(a).Feed and Growth enhancing
technologies
1.
2.
3.
4.
Major advances in feedstuffs and feeding in SA
Feed additives and antimicrobials
Efficient use of a variety of steroidal growth implants
Additive effects of beta-adrenergic agonists
(manipulate efficiency and leanness)
↓
Shift the growth curve (manipulate tissue growth) –
postpone fattening, and improve efficiency.
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6(b).Selection for growth
and efficiency
•
•
•
•
•
•
•
Selection of Cattle for  growth rate:
tenderness (due to age at slaughter)
carcass fat content,
flavour;
(DFD  environment + management)
ADG vs. SF rgenetic=-0,40 (age important)
More evident with compensatory growth
From Perry & Thompson (2005)
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6(c).Use of ADG, FCR, RFI
1. Selection for ADG increases growth rates & DMI
2. FCR correlate with ADG (-0.70)
3. RFI correlates with DMI (0,45), FCR (0,31)
a) High RFI = less efficient
b) High RFI bulls have high DMI and FCR
c) Low RFI bulls consume >10% less feed, with >9%
better FCR
d) Selection for better phenotypes – better
performance
e) Positive correlation between RFI and carcass fatness
4. Variation exists in RFI within breed types & Kleiber ratio’s
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6(d).Genomic technologies
• Advances in molecular genetics
• Identification of genes or genetic markers
associated with production / quality traits
• Candidate genes and genome scans to ID
loci associated with traits (QTL mapping)
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Genomic technologies vs. growth and meat quality
Species
Candidate gene
Trait
Pig
HAL,
MC4R,
RN, PRKAG3, AFABP/FABP4,
HFABP/FABP3,
CAST
IGF2
Meat quality /stress
Growth & fatness
Meat quality
IMF
Tenderness
Growth & fatness
Chicken
EX-FABP, L-FABP
Fatness
Cattle
CAST
Leptin, Thyroglobulin, Myostatin
DGATI
Tenderness
Fatness / marbling
Muscle growth
IMF / mabling
Sheep
Callipyge, GDF8
Muscular hypertrophy
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Consumer demand for lean meat
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Changes in fat content of red meat over time
(summary from Dr Nicolette Hall)
6(f).Ultrasound technologies and
metabolic hormones to select for
growth and efficiency
• IGF-I, insulin, glc, leptin
– useful but explain small proportion of variation
• Ultrasound scanning
– live animal measures are useful, but often not
practical.
– Explain variation but potential problems with
meat quality traits
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6(g).Consequence of physiological shift?
Changes in the phenotype and
production characteristics of modern
breeds of livestock – reproduction traits?
Sigmoidal growth curve and sequence
of physiological events remained
virtually unchanged
Rate and extent of these processes
increased remarkably
University of Pretoria
2015 Cattleman's Conference, SA Feedlot
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6(h). Physiological limits vs. meat quality?
Wet carcass syndrome
in mutton sheep breeds
Stress sensitivity and
PSE syndromes in highlean pigs
PSE in chickens
DFD in cattle
University of Pretoria
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Artistic expressions of Auroch in
caves at Lascaux and Altamira
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Modern phenotypic version of “Auroch”
7. Options to consider for beef cattle feeding?
 Feedlot cattle: 80 -120 days fattening period;
Longer fattening ~ 135 days?
 ADG  1,5 -2 kg/day; FCE  5 – 8:1
Healthy feeding: more 1,8 kg/days
Feedlot profit:
1. Premium for feedlot cattle
decreased from 21% to 2%
1. What you make is what you save
2. Better management:
a) Backgrounding
b) Breed, gender & type of weaner
c) Adaptation to grower
d) Healthy feeding
3. Quality systems
4. Classification / Variation in type
5. Non-conformers (mid-weights)
University of Pretoria
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Thank you
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