Genetic parameters for feet and leg traits evaluated in different environments

Area of Science:

• Animal Genetics
• Livestock Management
• Quantitative Genetics

Background:

• Feet and leg traits are crucial for dairy cattle welfare and productivity.
• Understanding genotype x environment interactions (GxE) is vital for accurate genetic evaluations.
• Previous research has not extensively evaluated GxE for feet and leg traits across diverse management systems.

Purpose of the Study:

• To investigate genotype x environment interactions (GxE) for seven key feet and leg traits in Holstein cattle.
• To estimate genetic correlations for these traits across different management systems (housing, flooring, hoof trimming).

Main Methods:

• Utilized first-lactation Holstein cattle records (n=147,400 to 145,160).
• Estimated genetic parameters using Restricted Maximum Likelihood (REML) and two-trait models.
• Compared traits across management systems: free vs. tie stalls, slatted vs. solid flooring, intact vs. trimmed hooves.

Main Results:

• Phenotypic scores for feet and leg traits were generally lower in tie stalls, on slatted floors, and with untrimmed hooves.
• Heritabilities for feet and leg traits were often higher in tie stalls and on slatted floors.
• Genetic correlations across management systems were high (≥0.85), except for rear leg rear view, indicating low GxE effects.

Conclusions:

• Genotype x environment interactions for feet and leg traits in Holstein cattle appear to be of minor importance.
• Current genetic evaluation procedures for feet and leg traits are likely robust across different housing, flooring, and hoof conditions.
• No modifications to genetic evaluation protocols seem necessary based on these management system comparisons.