Correlations of various direct and maternal effects for calving ease

Area of Science:

• Animal genetics
• Quantitative genetics
• Livestock breeding

Background:

• Calving ease is a critical trait in cattle breeding, influencing calf survival and economic returns.
• Understanding the genetic basis of calving ease in both young (heifers) and mature (cows) animals is essential for effective selection.
• Direct and maternal genetic effects play distinct roles in the inheritance of calving ease.

Purpose of the Study:

• To estimate heritabilities for direct and maternal calving ease effects in heifers and cows.
• To determine the genetic correlations between direct and maternal effects for calving ease within age groups.
• To assess the genetic correlation of direct calving ease effects between heifers and cows.

Main Methods:

• Utilized multitrait restricted maximum likelihood (REML) methods for parameter estimation.
• Analyzed data to estimate heritabilities and genetic correlations for calving ease traits.
• Separated genetic effects into direct (progeny) and maternal (dam) components.

Main Results:

• Heritabilities for direct calving ease effects were 4.9% in heifers and 1.1% in cows.
• Heritabilities for maternal calving ease effects were 4.8% in heifers and 0.7% in cows.
• Genetic correlations for direct/maternal effects were -0.40 in heifers and 0.07 in cows, with a high genetic correlation (0.995) for direct effects between heifers and cows.

Conclusions:

• Calving ease heritability and genetic correlations differ significantly between heifers and cows.
• The strong genetic correlation for direct effects suggests selection based on heifer performance can be effective for cows.
• Maternal effects on calving ease are more pronounced in heifers, indicating the dam's influence is crucial during first calving.