13. Estimation of breeding value in beef cattle 육우의 평가

B12 Estimation of breeding value in beef cattle

Places of investigation:

In field- farm, race, place, open range, exhibition. The breeding value estimation done at the farm evaluates the performances at the real place of production.

In station- centralized test station, individual feeding, control of live weight, evaluation of meatiness through ultrasound (rib eye area, live weight, cannon girth), conformation judgment, semen control.

Own performance traits:

Heritability values

• Most important performance traits in beef cattle
• Reproduction
• Calving interval
• Fertility
• Calving ease
• Docility  being quiet and easy to control, train
• Growth rate & gain
• Birth weight
• Gain (birth to weaning)
• Weaning weight
• Post weaning growth
• Feedlot gain
• Pasture gain
• Final feedlot weight
• Final yearling pasture weight
• Feed efficiency (feed conversion efficiency)
• Milk production
• Udder structure
• Conformation, height, mature size
• Weaning score
• Yearling pasture & final feedlot score
• Weaning (accustom to food other than its mother’s milk)
• Shoulder height, creep fed, non-creep fed
• Hip height, creep fed, non-creep fed
• Carcass merit
• Grade
• Dressing percent
• Carcass quality
• Ribeye area per hundredweight
• Fat thickness per hundredweight
• Marbling
• Tenderness
• Retail product, %, Retail product, kg​

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Detailed carcass traits & mean heritability estimates

• Carcass weight (0.40-0.50):

Indicates that carcass weight would respond well to selection

• Dressing percentage (0.30):

Moderately heritable but Less reliable (significant variability btw estimates) Adjusted back fat

• thickness (0.40-0.50):

Suggests that genetic progress to single trait selection would be possible if records were available

• Longissimus muscle area (~0.40)

Easy measurment

Indicates that longissimus muscle is moderately heritable & genetic gain might be achieved through selection

• Kidney, pelvic & heart fat percentage (0.40)
• Marbling score (0.40-0.50)

One of most genetically evaluated carcass traits

• Yield grade (0.6)
• Highly heritable trait

Genetic merit may be improved through selection Predicted % of retail product (0.40)

• Retail product weight (0.50)

Significant genetic variation exists to improve retail product weight by selection

• Fat weight (0.50)

Suggests that selection against fat weight would respond well to selection

• Bone weight (0.50)

Actual retail product percentage (0.50-0.60)

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