BEEF SPECIES SYMPOSIUM: Beef production without mature cows.

Area of Science:

• Animal Science
• Reproductive Biology
• Sustainable Agriculture

Background:

• Mature beef cows allocate over 80% of annual nutrient intake to maintenance.
• Beef production's inefficiency is largely due to the nutrient demands of maintaining cow herds.
• Nearly half of all nutrients in the U.S. beef system support cow herd maintenance.

Purpose of the Study:

• To propose a modified single-calf heifer system using sexed semen to enhance beef production efficiency.
• To decrease the size of the beef cow herd and minimize nutrient waste.
• To increase the ratio of nutrients partitioned to growth versus maintenance.

Main Methods:

• Utilizing sexed semen to ensure most heifers produce heifer calves.
• Implementing additional management practices such as artificial insemination (AI) and early weaning.
• Calving two-year-old heifers requires specific management attention.

Main Results:

• Significant reduction in cow herd size, leading to decreased nutrient consumption and waste (e.g., methane).
• Increased efficiency by shifting nutrient partitioning from maintenance to growth.
• Elimination of breeding back first-calf heifers, castration, and reduced incidence of health issues in older cows.

Conclusions:

• The proposed system, despite challenges like lower conception rates with sexed semen and slower female growth, offers substantial efficiency gains.
• Decreasing cow herd size is key to improving nutrient use and reducing environmental impact.
• Accelerated genetic progress is achievable due to a decreased generation interval.