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Improvement of Beef Cow
Biological Efficiency
Dan Shike, PhD
University of Illinois
Champaign-Urbana
Why all the buzz about efficiency?
• Increasing world population
• Increased utilization of feed for fuel
• Increasing feed cost (including forages)
• Other inputs increasing in cost
– Fuel, transportation, fertilizer
Profitability
• Traditional focus on outputs
• Feed costs have historically been 50-70% of the cost
of production in beef enterprises
• As corn prices approached and exceeded $7 per
bushel, feed costs were nearly 80% of the costs in
many feedlot operations in US
Feed Efficiency
Feed:Gain
< 2:1
< 3.5:1
> 6:1
Why are beef cattle less efficient?
• Maintenance requirements
– 50% of total energy
expended in beef
production is used for
maintenance of the cow
• High fiber diet
– Rumen fermentation
– Bacteria produce VFA
– Bacteria produce methane
Why haven’t we made any progress?
• No selection for feed efficiency
• Why?
– Requires individual feeding
• Expensive facilities
• High labor requirement
• Lack of social interaction decreases
feed intake
– Difficulty in defining efficient
female
Measures of feed efficiency
• Feed conversion ratio (FCR)
• Residual feed intake (RFI)
• Residual BW gain (RG)
Measures of efficiency
• Residual Feed Intake (RFI)
– The difference between actual intake and predicted
intake based on animal’s gain, maintenance
requirements for its body weight, and composition
– NEGATIVE RFI IS GOOD!
• Required less feed then predicted
– Independent of growth and mature size
– Linked to biologically relevant traits associated with
feed efficiency
• Digestibility, heat production, protein turnover
Measures of efficiency
• Residual BW Gain (RG)
– The difference between actual gain and
predicted gain based on animals intake,
maintenance requirements for its body weight,
and composition
– POSITIVE RG IS GOOD!
• Gained more weight than predicted
– Correlated to growth
Beef cow efficiency
• What about cow efficiency?
– ~70% of feed resources for cowherd
– ~70% of feed for maintenance
– 50% OF ALL FEED TO MAINTAIN COWHERD
• How do we define cow efficiency?
– Pounds of calf weaned per cow exposed
– Pounds of calf weaned per cow exposed
per unit of feed energy consumed
– What about longevity?
Efficient Cow
• Can you tell by looking at them?
Maintenance energy
High Maintenance Cow
Low Maintenance Cow
•
•
•
•
•
•
•
•
•
•
High milk production
High visceral organ weight
High body lean mass
Low body fat mass
High output and high input
Low milk production
Low visceral organ weight
Low body lean mass
High body fat mass
Low output and low input
Environment
Restricted feed resources
Abundant feed resources
• Favors more moderate size,
moderate milk production
• “Low maintenance” breeds
are most efficient
• Favors larger, heavier
milking biological types
• “High maintenance” breeds
are most efficient
– Angus, Red Poll
• High maintenance breeds
are least efficient
– Simmental, Charolais,
Limousin, Gelbvieh
– Simmental, Charolais,
Limousin, Gelbvieh
• Low maintenance breeds
are least efficient
– Hereford, Angus, Red Poll
Jenkins and Ferrell, 1994
Cow efficiency research
• Funded by American Angus Association
– Post-weaning intake evaluation on replacements
– All females given opportunity to breed
– Evaluate 2-year-old cows
• 60 d postpartum evaluation period
– 2 week intake evaluation
– BW, body condition score, ultrasound fat, milk production
• 240 d postpartum evaluation
– 2 week intake evaluation
– BW, body condition score, ultrasound fat
– Repeat again as 5-year-old mature cows
Variation in cow efficiency
Small
Cow
Big Cow
Moderate
Cow
Moderate
Cow
BW, lbs
1186
1453
1305
1307
Milk Production, lbs
15.9
22.9
17.9
20.5
BCS
5.5
6.0
6.0
5.5
DMI, lbs
56.7
45.4
54.5
35.7
Adcock et al., 2011
Correlations of heifer and
2 year-old cow traits
CowL
DMI
Heifer
DMI
Heifer
RFI
Heifer
RG
CowL
BW
CowL
Milk
CowDry
DMI
CowDry
BW
0.45
-0.21
-0.17
0.42
0.09
0.20
-0.01
-0.04
0.15
0.02
-0.11
0.12
-0.05
-0.05
0.14
CowL = Cow traits at 60 d postpartum (lactating)
CowDry = Cow traits at 240 d postpartum (dry cow)
Correlations in bold are significant at P ≤ 0.05
Ongoing project
• Intake on 486 heifers postweaning
• Intake on 274 2-year-old cows
• Intake on 34 5-year old cows
– 2nd year of 5-year-old cows this year
• Continue to evaluate fertility, productivity,
and longevity
► Is
there a genetics x diet interaction for
intake or RFI?
 Feedlot
efficiency trials – high-energy, grain-based
 Cowherd – moderate to low-energy, forage-based
► Why
would they be the same?
 Maintenance
turnover)
► Why
energy (heat production, protein
might they be different?
 Intake
regulation
 Grain – chemostatic
 Forage – fill-regulated
► 162
spring-born, Charolais-sired calves
► 274 fall-born, Charolais-sired calves
► Period 1 (half on forage; half on grain)
3
week transition / adaptation period
 2 day initial and final weights (70 d test)
 Ultrasound 12th rib fat thickness at start and finish
 Weighed every 2 weeks
► Period
3
2 evaluation (all cattle on grain)
week transition/adaptation period
 2 day initial and final weights (70 d test)
 Ultrasound 12th rib fat thickness
 Weighed every 2 weeks
Forage
Grain
Ingredient
% of diet, DMB
Ingredient
% of diet, DMB
Husklage
47.5
20
Alfalfa haylage
47.5
High moisture
corn
Supplement
5
Ground corn
30
Husklage
25
DDGS
15
Supplement
10
NEm = 1.557 Mcal/kg
NEg = 0.956 Mcal/kg
Target 2 lbs/d gain
NEm = 2.004 Mcal/kg
NEg = 1.359 Mcal/kg
Target 4 lbs/d gain
Item
Forage
DMI
Forage
ADG
Forage
RFI
Grain
DMI
Grain
ADG
Forage
DMI
Forage
ADG
Forage
RFI
Grain
DMI
Grain
ADG
Grain
RFI
1
0.69
0.58
0.57
-0.09
0.26
1
0.00
0.51
0.01
0.13
1
0.21
-0.06
0.41
1
0.53
0.58
1
0.00
Grain
RFI
1
Correlations in bold are significant at P ≤ 0.05
Item
Forage
DMI
Forage
ADG
Forage
RFI
Grain
DMI
Grain
ADG
Forage
DMI
Forage
ADG
Forage
RFI
Grain
DMI
Grain
ADG
Grain
RFI
1
0.70
0.51
0.62
-0.29
0.15
1
0.00
0.40
-0.22
-0.04
1
0.28
0.01
0.35
1
0.18
0.66
1
0.00
Grain
RFI
1
Correlations in bold are significant at P ≤ 0.05
Summary
• Variation in feed intake and efficiency
– Opportunity to select for and improve
• Best measure / definition of efficiency?
– Depends if it is feedlot or cowherd
– Depends if it is for selection or research
• Need to continue to collect phenotypes
– Need INTAKE
– Understand relationships of traits
– Geneticists will determine best tools for selection
Questions?

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