Genetic relationships between feed efficiency in growing males and beef cow performance

Area of Science:

• Animal Science
• Genetics
• Beef Cattle Production

Background:

• Feed efficiency is crucial for beef cattle profitability, yet research often overlooks its impact on the cow herd.
• Most studies focus on young animals, neglecting the long-term economic contributions of mature cows.

Purpose of the Study:

• To quantify genetic covariances between feed efficiency in growing beef bulls and various cow performance traits.
• To assess the impact of selecting for feed efficiency on fertility, survival, calving, body weight, maternal weaning weight, cow value, and carcass traits.

Main Methods:

• Utilized a large dataset including feed efficiency data from 2,605 purebred bulls.
• Analyzed performance records from up to 94,936 crossbred beef cows.
• Estimated genetic covariances using animal and animal-dam linear mixed models.

Main Results:

• Selection for feed efficiency (feed conversion ratio or residual BW gain) positively impacts maternal weaning weight.
• Residual feed intake showed a negative genetic correlation with cow body weight, though with a large standard error.
• No significant correlations were found between feed efficiency traits and fertility, calving difficulty, or perinatal mortality.

Conclusions:

• Selection for improved feed efficiency in beef cattle is unlikely to negatively affect most cow performance traits.
• A potential trade-off exists, as improved feed efficiency may delay the age at first calving, possibly due to delayed puberty.
• Further research may be needed to fully understand the implications of feed efficiency selection on reproductive timing.