There is little debate about that. With that in mind, let’s look at some differences in feed intake based on differences in cow weights.
The following are dry matter requirements for cows in peak lactation (60 percent total digestible nutrients and 12 percent crude protein) per head per day. A 1,200-pound brood cow needs approximately 24 pounds. A 1,400-pound mature cow needs approximately 27 pounds.
Mature cows weighing 1,600 pounds need approximately 31 pounds. The 1,800-pound wonder cow requires approximately 33 pounds. These are approximations based on weight. They do not account for adverse weather, breed type and genetic differences in the cow population.
Each pound of forage and feed has a cost assigned to your bottom line. If heavier cows can wean additional pounds, then there is hope.
For illustration, let’s expect mature cows should wean a calf that weighs 45 percent of their bodyweight. Using that as our standard, here are example cow weights (in pounds) and corresponding calf weights (in pounds): 1,200 – 540; 1,400 – 630; 1,600 – 720; 1,800 – 810. Many may ask why anyone would have 1,600- and 1,800-pound cows. They happen more than we might think.
As an anecdotal example, I broke down some of the recent weaning and cow weight (3 to 12 years old) information at the Northwest Georgia Research and Education Center. The 59 head of cows weighing between 1,220 and 1,395 pounds weaned calves at 617 pounds with an average percent dam weight of 45 percent.
The 56 head of cows weighing between 1,400 and 1,495 pounds weaned calves weighing 617 pounds on average (averaging 41 percent of dam weight). The 24 head ranging from 1,500 to 1,600 pounds weaned calves weighing an average of 613 pounds (averaging 39 percent of dam weight).
Last, 10 head weighing between 1,605 and 1,695 weaned calves averaging 611 pounds (averaging 35.5 percent of dam weight).
This is far from a science, but it should make us pause and think about how cow inputs affect the bottom line. Each of these small groups of cows weaned calves at a similar weight. The cows in the heavier groups will require more inputs to get the same return. Until next time. 
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Jason Duggin
- Beef Extension Specialist
- University of Georgia
- Email Jason Duggin
