Genetic parameter estimates and expected progeny differences for mature size in Angus cattle

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Beef Cattle Breeding

Background:

• Accurate estimation of genetic parameters for mature size traits in Angus cows is essential for effective breeding programs.
• Mature size influences cow longevity, productivity, and overall herd efficiency.

Purpose of the Study:

• To estimate heritabilities, genetic correlations, and EPD for mature weight and mature height in Angus cows.
• To investigate the impact of body condition score adjustment on these estimates.
• To assess genetic relationships between mature and immature cow weights.

Main Methods:

• Utilized mature size records from 2,732 Angus daughters of 256 sires.
• Employed REML procedures with a two-trait sire model for variance component estimation.
• Investigated linear models with and without body condition score adjustments for weight.

Main Results:

• Heritability estimates for mature weight ranged from 0.45 to 0.48, and for mature height from 0.83 to 0.83.
• High genetic correlations were observed between mature weight and height (0.66-0.78).
• Spearman rank correlations for sire EPD between adjusted and unadjusted data were high (0.94 for weight, 0.99 for height).

Conclusions:

• Mature weight and height in Angus cows are highly heritable traits.
• Genetic selection for mature weight is expected to result in correlated increases in mature height.
• EPD derived from adjusted and unadjusted data show high agreement, supporting their utility in breeding decisions.