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Effects of Two Measures of Disposition on Post-weaning Gain of Beef Calves

Investigating how disposition traits affect post-weaning gain in beef calves through subjective and objective measures like Pen Score and Exit Velocity, with genetic implications for selection.

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Effects of Two Measures of Disposition on Post-weaning Gain of Beef Calves

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  1. Effects of Two Measures of Disposition on Post-weaning Gain of Beef Calves R. L. Weaber, Ph.D.WeaberR@missouri.edu F. E. Creason Division of Animal Science University of Missouri-Columbia

  2. 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 BIF Live Animal, Carcass and End Point, Choctaw, MS

  3. 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 BIF Live Animal, Carcass and End Point, Choctaw, MS

  4. Exit Velocity Infrared Eye Infrared Eye 6 ft 6 ft Chute BIF Live Animal, Carcass and End Point, Choctaw, MS

  5. Data Collection • Steers Weight • Initial- Avg. 533.94 ± 5.39 lbs (242.70 ± 2.45 kg) • Finished- Avg. 701.65 ± 1.78 lbs (318.93 ± 3.08 kg) • 55 Day Gain- Avg. 167.71 ± 2.45 lbs (76.23 ± 1.12 kg) • ADG=3.05 lbs/day (1.38 kg/day) • Steers Disposition • PS= Avg. 2.09 ± 0.11 • EV= Avg. 7.38 ± 0.16 ft/s (2.25 ± 0.05 m/s) BIF Live Animal, Carcass and End Point, Choctaw, MS

  6. Data-Distribution BIF Live Animal, Carcass and End Point, Choctaw, MS

  7. Data-Distribution BIF Live Animal, Carcass and End Point, Choctaw, MS

  8. 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) BIF Live Animal, Carcass and End Point, Choctaw, MS

  9. Results-Linear Model • Steers with faster EV gained less -11.88 ± 4.7 lb/sec (-5.39 ± 2.13 kg/sec) BIF Live Animal, Carcass and End Point, Choctaw, MS

  10. Results-Correlations Correlation-a measure of linear relationship between two variables. All P < 0.05 BIF Live Animal, Carcass and End Point, Choctaw, MS

  11. Future • 330 head of MFA steers on trial • 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 • Half-sib heifers to steers • Correlate disposition scores with conception rates • Genetic evaluation of disposition using EV and PS BIF Live Animal, Carcass and End Point, Choctaw, MS

  12. Questions Thank You! BIF Live Animal, Carcass and End Point, Choctaw, MS

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