Manage Young Cows to Rebreed

The old rule of thumb that a heifer should reach 65% of her mature body weight by the start of breeding season still holds, said Tom Geary of the USDA-ARS Fort Keogh Research Center, Miles City, Mont. “The difference is that producers translate this into meaning 650 to 750 pounds (lb.), which was adequate when we were kids and mature cow weights were 1,000 to 1,100 pounds.” Today, mature weights are often 1,250 lb. or more, meaning heifers should be at least 800 lb. at the onset of breeding.

Geary provided insights as to what factors contribute to rebreeding problems and how to overcome them at a reproductive symposium hosted by the National Association of Animal Breeders (NAAB) May 28, 2003. The symposium preceded the 35th Annual Beef Improvement Federation (BIF) Meeting in Lexington, Ky.

To improve rebreeding performance of young beef cows, Geary suggested:
• Develop heifers to 65% of mature weights by breeding.
• Synchronize heifers to conceive early during a short breeding season.
• Artificially inseminate heifers with semen from calving-ease sires.
• Provide additional energy during the last 50 days of gestation so that heifers calve at a minimum body condition score (BCS) of 5.
• Provide early calving assistance when intervention is needed. (Every 30-minute delay in providing calving assistance increases the postpartum interval by 6 days, Geary said.)
• Provide young cows with the best feed resources available after calving.
• Provide ionophores to cows after calving to improve utilization of feed.
• Expose young cows to sterile bulls or androgenized cows during the last 30 days before the start of breeding.
• Induce/synchronize estrous cycles in young cows even with natural service.
• Consider early weaning during drought and cheap feed availability.

To access the proceedings paper or the audio of Geary’s presentation, visit the newsroom.

— by Shauna Rose Hermel