Reproductive success governs production efficiency in beef cow-calf operations. The University of Kentucky Beef Integrated Reproductive Management (Beef IRM) team developed a multi-disciplinary program to help cattlemen adopt production practices that favor high reproductive rates in their cow herds. The educational model of this program combines traditional classroom with an extensive hands-on, learn-by-doing methodology. UK Extension employs this model as an effort to increase behavior modification. The UK IRM Farm Program is designed to be a long-term project (5-7 years) in order to accurately demonstrate the impact of controlling reproduction.

Ten years ago, the UK Beef IRM Committee began a long-term project with two cattlemen in Anderson County to demonstrate the long-term impact of use of estrous synchronization and AI (ESAI). The components of the breeding system included ESAI with natural service (70-day season), organized crossbreeding (Angus, Hereford), and organized selection for the environment (limit purchase feed) and market (post-weaning and bred heifers). One farm was large for the Southeast (150-200 head) while the other was average (23-25 head). At the beginning of the project, average cow size was 1570 lbs and 1750 lbs for the large and small farm, respectively. 

Over the next 7-9 years, cows from these farms were subjected to ESAI and natural service. AI sires were selected to maximize heterosis in a two-breed rotation and to decrease mature cow size while minimizing the impact of weaning performance. Cows were rapidly replaced (15-25% replacement) on both farms with females that were sired by our chosen AI sires.

On both farms, average cows size decreased considerably over time. What impact could this have on production efficiency. Cows typically consume 2-3% of their weight daily on as-fed basis. If we assume that these cows were eating 2.5% of their BW, then, at the beginning, the 1750 and 1570 lbs cows were eating about 44 and 39 lbs of feed per day, respectively. During this project, average cow size has decreased to 1360 lbs for both herds. Cows that size will eat about 34 lbs of feed per day or about 1 ton fewer pounds for feed per year per cow. That’s a lot of feed. That’s a lot of savings.

Reducing cow size normally is associated with a reduction in productivity. Instead, averaging both farms together, the length of the calving season decreased (35 days), pregnancy rate increased (8%), the average age of calf increased (17 days), weaning rate increased (10%), adjusted weaning weight increased (118 lbs), and the pound of calf weaned per cow exposed increased (106 lbs). 

One of our main goals was to increase cow efficiency. An “efficient operation”, as defined above, compares production with the costs. If we use cow size as a rough estimate of our cost, we can estimate cow efficiency by dividing the percent body weight weaned by the total by the number of cows exposed to breeding. Why are we dividing %BW Weaned by the number of cows exposed? Why not just look at average %BW Weaned? Because the successful cows, those that wean a calf, have to be efficient enough to pay for the cows that fail. Cow efficiency increased over time. In this project, when we started, the 1660 lb cows were weaning about 488 pounds. So, these cows were weaning about 29% of their body weight and about 24% of their body weight per cow exposed to the bull. To date, using this estimate, cow efficiency has increased approximately 10%. 

The UK IRM Farm Program has made a tremendous on these two farms. Their cows eat approximately 1 ton fewer pounds per year ($40,000 per year savings) while producing 106 more pounds of calf (added revenue $31,800). Total impact was $359 per cow.