Nutrition
Nutrition Articles
Cow Body Size Considerations for Efficient Production
There have been good discussions about mature cow size and what this means for efficient production. The premise is that small cows need less feed per day to be maintained than a larger body cow. Looking at the daily energy requirement for a 1000 lb. cow compared to a 1350 lb. cow in midgestation during winter in Canada, the daily requirement for Net Energy (NE) would be 11.5 Mcal/day for the smaller cow and 16.1 Mcal/day for the larger cow. Arguments for the larger cow centre on easier calving, a bigger calf, and better growth rate for the calf in the feedlot. The cost for maintenance is higher for the large cow, but she produces a bigger return once her calf is finished, has fewer calving problems and gives a good return as a culled animal. Arguments for the smaller cow are higher stocking rates per acre for grazing and lower daily feed costs.
Dr. Dave Lalman from Oklahoma State University recently discussed this topic and had some interesting points to add to the understanding of what options are available to the producer. He said that the cow/calf owner does not see the benefits of better gain as that accrues to the feedlot owner. In looking at the costs in today’s cost structure, the increased cost of maintaining the larger cow is about equal to the value of the increased gain. Under a lower value structure for finished animals the higher cost of maintenance would not be recovered.
The smaller cow does have a lower daily need for energy, giving a lower maintenance cost. However, calving difficulties may increase, she may produce a smaller calf, and this calf would likely grow slower. In addition, she contributes less money as a cull cow. There is a connection between the cow’s mature body weight and the rate of gain for her calf.
Dr. Lalman presents another option by looking at what individual cows in the herd are doing. On examination of daily intake coupled with mature body weight his studies show four groups of cows. Those with low body weight eating low amounts of feed and those with low body weight eating high amounts of feed. Then there are cows with high mature body weight eating high amounts of feed and those with high body weights eating low amounts of feed (see Fig. 2).
Figure 1. The idea in Figure 1 is to select heifers with an EPD for intake of around .5, who eat well but not too much. Then also include a mature body weight EPD around 0 to slow the annual weight increase of the cow herd. Those in the top left quadrant are candidates for selection. The red circle was added by the author.
The desired group of cows would be those of average body weight eating low amounts of feed compared to breed averages. This management move over time stabilizes or reduces the acres needed to maintain the herd.
Furthermore, these ideal cows would be selected to thrive on medium and low-quality forages. Cow herds historically have been selected for increasing mature body weights using high energy inputs. In some herds these animals couldn’t perform well if they had to depend on what their natural surroundings produce. Examine the red box in Figure 2. We see these animals are not performing well regardless of how much they eat daily. In drought years expensive inputs would be needed to keep performance up causing financial hardship. Rations for these selected animals can be efficiently blended using high and low quality forages plus minerals using Highline’s mixers which combine all ingredients very well with a low coefficient of variance, below 3%. The efficient use of high cost forages keeps the cost of production lower.
The studies are ongoing and are producing new insights for the beef cow owner. Recommendations at this point include changing the focus on selection of bulls for replacement heifers to include Mature Body Weight EBV’s over .5 for a mature weight slightly below breed average and a Daily Intake where the EBV is over .5 for breed average. This action would begin to produce heifers of body weights at or slightly below breed average that eat efficiently. This type of animal would thrive on natural grass pastures and require less high energy grain inputs to maintain productivity. The idea is that this approach would slow the constant annual increase in body weight while maintaining performance.
This is helpful data on cow performance on natural grass-based production systems and can help producers going forward where drought can affect cost of production negatively by raising ration ingredient costs.
1. Information drawn from presentation by David Lalman, PhD, at the Beef Reproduction Task Force’s 2025 Applied Reproductive Strategies in Beef Cattle Symposium held Sept. 17 & 18 in North Platte, NE.
2. Figure 2. Finding Forage Efficient Heifers, OSU specialists share strategies for improving forage efficiency in replacement females, By David Lalman - Oklahoma State University, by Bailey Tomson, Oklahoma State University, December 18, 2025 Drovers Magazine.