Extra Energy of Young Females After Calving
The 1996 Nutrient Requirements for Beef Cattle indicates that the first-calf females, post-calving, needs to consume a diet that is between 62% and 64% TDN and 10% to 11% crude protein, depending on level of milk production. These nutrient densities also assume that females are being fed to maintain body condition post-calving, not trying to increase body condition.
If you have meadow hay that tests 58% TDN and 12% crude protein, prairie hay that tests 54% TDN and 6.5% crude protein, bromegrass hay that is 58% TDN and 11% crude protein, or early-bloom alfalfa at 60% TDN and 20% crude, feeding a combination of these feeds or any of these feeds individually, will not meet the first-calf-female's energy (TDN) needs for sure and some of these forages will not meet their protein needs. Based on the information given in the previous paragraph, a feed that is high in energy will need to be added to the diet to meet the TDN needs.
There are a number of feeds that will fit nicely into these diets depending on where you are located. Corn grain, corn silage, distillers grains, corn gluten feed, wheat mids, soy huls just to name a few. The grain by-products (distillers grains, gluten feed, wheat mids, soy huls) fit nicely because they don't have a negative interaction with forage digestion. If you had the bromegrass hay and had access to dried distillers grains and the heifers after calving weighed about 1,000 pounds, then about 23 pounds per head per day of the bromegrass hay and 3 pounds per head per day of dried distillers grains would meet both the protein and energy needs. If both these feeds are about 90 percent dry matter, these females will be consuming about 2.3 to 2.4 percent of their body weight which is well within the intake capabilities of these females.
When feeding these kinds of rations, make sure all females have access to their fair share.
Also, you could feed the hay through a bale processor or in a round bale feeder and offer the energy source in a bunk or fed on frozen ground. Feeding losses on frozen ground are minimal. If you do feed supplement on frozen ground, feeding next to a fence on a slight up-hill slope would eliminate cows walking on the supplement.
Remember that the first-calf-female has a smaller rumen than that of the mature cow. Because of this, nutrient quality of the diet is very important and low quality feeds likely do not fit into these rations. As always, sample and test forages for quality. Target the high quality forages for the first-calf-females after calving and for the developing replacement heifers. When following this strategy, less supplemental feeds will need to be purchased. Salt and fresh water are important. Vitamin and mineral supplementation need to be adjusted based on diet ingredients.
Dr. Rick Rasby, Professor of Animal Science
Animal Science, University of Nebraska - Lincoln, Lincoln, NE