Heifer Development: Rebreeding 1st Calf Heifers
By: Taylor Grussing and George Perry, SDSU Extension
According to the USDA-NASS Cattle Inventory Report that was recently released, beef producers across the country are expected to calve 106% more beef heifers than last year. With this in mind, producers will also be breeding more 2-year old females this year. As pregnancy is the number one reason why cows are culled from the herd annually, we hope to rebreed these young females early for addition into the mature cow herd.
SDSU Extension is in the process of hosting a “Heifer Development Webinar Series” designed to provide valuable information to producers looking for resources to effectively manage bred heifers and integrate them into the herd for years to come. The fourth and final session in the four-part webinar series will focus on Reproductive Management and Rebreeding 1st Calf Heifers. We will focus on 4 areas of management: performance, nutrition, longevity and reproductive technologies.
Before discussion of reproductive strategies even begins, we need to evaluate each female and her performance over the last year and through her first calving. Evaluating her performance prior, during and after calving will give insight into how she will rebreed. Producers should evaluate: calving performance (unassisted or pulled), mothering ability, udder quality, milk production etc. If young females have a difficult calving event, this may be a detriment to her rebreeding within a defined breeding season due to extra stress and damage to her reproductive tract. Such occurrences should be documented in the calving/record book so when breeding time comes around, options are available.
The goal is to have 1st calf heifers developed to 85% of mature body weight by calving time and in a body condition score of 6. All young females need to be assessed for body stores after calving in order to know if condition needs to be added by breeding time. If she is thin, extra energy will need to be supplemented in order for her to meet nutrient demands of lactation, growth and maintenance, as well as reproduction. It is best for females to be on an increasing plane of nutrition by the breeding season to enhance conception results.
After calving, females go through a period of postpartum where she is recovering from calving, undergoing uterine involution and resuming activity on her ovaries. If producers calve heifers before the mature cow herd, they have slightly more than 80 days for 1st calf heifers to resume estrous cycles and rebreed in order for them to fall into a yearly calving interval of 365 d with the mature cow herd. Females that calve during the 1st part of the calving season have more time to resume cycles and rebreed; however, later calving females may need assistance in resuming fertile cycles.
Last but not least, specific reproductive techniques and estrous synchronization protocols can be utilized to help young females resume estrous cycles and rebreed early in the breeding season. If any females calved late or had difficult births, these systems also may be utilized to boost estrous cycles and move late calving females up into earlier breeding period. Lastly, mating decisions for 2-year old females should be strategically selected based on her genetics, calving performance and genetic goals of the operation. The ultimate goal of breeding these young females should be to rear calves which will complement the mature cow herd and match the goals of the operation.
The webinar on Rebreeding First-calf Heifers will run March 2nd at 12:30 PM CST/11:30 AM MST and last for one hour. A one-time registration fee of $25 is required for access to webinar sessions. To register please visit the webinar event page on iGrow. To learn more or if you have questions, contact Taylor Grussing, SDSU Extension Cow/Calf Field Specialist.