Pasture conditions are deteriorating, and hay inventory is short. If you’re out of grass and about to start feeding hay, it’s time to take drastic action to maintain your cow herd and prevent further injury to pastures. Many areas in the West and southern Great Plains have seen high culling rates, with cows going to town in droves. Once all the old, open or nonproductive cows are culled, the next step for many producers is to wean calves early.
It is much harder to maintain or add condition to a cow that still has a calf on her side. A dry pregnant cow in the second trimester requires 37 percent less total digestible nutrients (TDN) and 13 percent less protein than when she is in late lactation with a calf. The dry pregnant cow not only requires less energy and protein, but she also would eat 20 percent less than the lactating cow.
Research shows that calves can be weaned as early as 45 days of age, and these calves grow to similar or heavier weights by normal weaning time. Spring-born calves in mid-to-late August are currently 3-5 months of age and likely weigh 300-400 pounds. Even though they are much lighter than our normal calf weights at weaning, it is still relatively simple to feed these lightweight calves grower diets in drylots to maintain targeted sales weights by normal marketing time.
Early-weaned calves can be grown in drylots very efficiently with the feed-to-gain ratio expected to be 4.5 to 5 lbs. of feed per pound of gain. Because these calves are smaller and immature, they should be fed growing rations with targeted gains of 2 to 2.5 lbs. per day, depending on frame size and growth potential.
This size calf would be expected to eat about 3 percent of their body weight per day on a dry matter basis, but the lighter calves require 18 percent crude protein diets until they weigh over 400 lbs. Table 1 is an example of a 18 percent crude protein ration that can be fed to lightweight growing calves. Consult with your local Extension agent or feed company representative for locally available feedstuffs.
Table 1. Example of an 18 percent crude protein ration
Ingredient
% of ration
Alfalfa hay
14.0
Cottonseed hulls
14.0
Corn gluten feed
17.0
Dried distillers grains with solubles
22.0
Soybean hulls
12.0
Ground milo or corn
15.0
Molasses
5.0
Limestone
0.8
Salt
0.2
Diet composition
Dry matter (DM), %
90.0
Crude protein, % of DM
18.0
Total digestible nutrients, % of DM
73.0
Net energy for maintenance, Mcal/lb. DM
0.76
Net energy for gain, Mcal/lb. DM
0.48
Keith Lusby and Don Gill had the following observations and conclusions on the early weaning of calves:
• Early weaning is a predictable method of salvaging high reproduction rates during droughts and other emergencies.
• The early-weaned calves are pretty tough and learn to eat palatable rations quickly.
• Health problems when calves are weaned and kept on the ranch have been minimal.
• Early-weaned calves should be managed on the ranch or with only a short haul for a period of time after weaning.
• Managing these calves in a commercial feedlot is risky and takes coordination among the owner, feedlot manager, consulting veterinarian and consulting nutritionist. Mistakes here can have long-term and often fatal consequences. — Paul Beck, Oklahoma State University Extension beef nutrition specialist
