work toward genetic improvement of disposition in beef cattle
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Work Toward Genetic Improvement of Disposition in Beef Cattle. R. L. Weaber, Ph.D. [email protected] Division of Animal Science University of Missouri-Columbia. Why Improve Disposition?. Poor disposition creates dangerous settings for: Animals Workers - PowerPoint PPT PresentationTRANSCRIPT
Work Toward Genetic Improvement of Disposition in Beef Cattle
R. L. Weaber, Ph.D. [email protected] Division of Animal ScienceUniversity of Missouri-Columbia
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Why Improve Disposition?
Poor disposition creates dangerous settings for:– Animals – Workers
Increased wear and tear on facilities and equipment
Interaction between disposition (fearfulness) and production traits– Gain, feed intake, marbling, tenderness
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Phenotypic Measures
Subjective measures of disposition:– Chute Score (1-6)– Pen Score (1-5)
Objective Measures– Flight Time– Exit Velocity (m/sec)
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Is it heritable?
Chute Score h2 = 0.26-0.40 Pen score h2 = 0.35 Exit Velocity
– single measure h2 = 0.35– Avg. of two or more measures
h2 = 0.44-0.50
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Genetic Correlations :
Trait Correlation w/ Flight Time
Carcass Wt. 0.05
Retail Yield 0.11
Marbling -0.05
Shear Force -0.48
Meat Color -0.18
(Burrow, 2003)
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NALF Docility Genetic Evaluation
First published in 1998Heritability = 0.40
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Mizzou Research Objectives Establish relationship between disposition
and production traits Evaluation of subjective and objective
measures of disposition Investigate relationship of serial measures of
disposition Estimate genetic relationships between
measures of disposition and production traits Produce genetic evaluation for selection at
MO-AES
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Materials and Methods 111 Spring Born Angus Cross Steers
– Known Pedigree– MFA Health Track Program
Disposition– Pen Score (PS)
• 1=Gentle, 5=Aggressive
– Exit Velocity (EV)• ft/sec
Weight Gain– Back-grounding period - 55 days post-weaning– Diet included self-fed concentrate and
improved fescue pastures
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Exit Velocity
6 ft 6 ftChute
Infrared Eye
Infrared Eye
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Exit Velocity Histogram
0
5
10
15
20
25
30
35
40
3.4 4.7 6.0 7.3 8.6 9.9 11.2 12.5
Exit Velocity (ft/s)
Fre
qu
en
cy
Data-Distribution
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Data-Distribution
Pen Score Histogram
05
1015202530354045
1 2 3 4 5
Pen Score
Fre
qu
en
cy
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Data Analysis
Fixed Effects– Pen Score– Exit Velocity
Random Effect– Sire
Full Model (EV, PS, Sire)– EV only significant source of variation (P < 0.05)– Faster flight times were negatively associated with weight
gain Reduced Model (EV, Sire)
– EV and Sire both significant (P < 0.05)
. i i i ji iWt Gain EV PS Sire e
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Results-Linear Model
Steers with faster EV gained less-11.88 ± 4.7 lb/sec (-5.39 ± 2.13 kg/sec)
EV Std. Dev (1.64 ft/s)
EV (ft/s)
Gain Gain Difference
ADG ADG Difference
-2 4.1 206.68 38.97 3.76 0.71-1 5.7 187.19 19.48 3.40 0.350 7.4 167.71 0.00 3.05 0.001 9.0 148.23 -19.48 2.70 -0.352 10.7 128.74 -38.97 2.34 -0.71
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Results-Correlations
PS EV WGPS 1.00 0.36 -0.21EV 0.36 1.00 -0.24WG -0.21 -0.24 1.00
All P < 0.05
Correlation-a measure of linear relationship between two variables.
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Results-Correlations
EV1 EV2 PS WTEV1 1.00 0.59 0.38 -0.25EV2 0.59 1.00 0.42 -0.36PS 0.38 0.42 1.00 -0.35WT -0.25 -0.36 -0.35 1.00
All P < 0.05
Correlations between serial exit velocity measures when cattle went on-feed and pen-score
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Future
330 head of MFA steers All weight gain and carcass data
collected– 2/3 have individual feed intake measured– Establish relationship between disposition,
efficiency, gain and carcass merit– Various hormone profiles
Genetic evaluation of disposition using EV and PS
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Questions
Thank You!