Protein Requirements for Pregnant Cows
Tips for determining if and how much of a supplement is needed.
Nutrient requirements in early gestation are similar to maintenance requirements, but as the fetus grows, the cow’s nutrient needs increase. Jeremy Martin, ruminant nutritionist and reproduction manager for Great Plains Livestock Consulting of Eagle, Neb., says weather can be a significant factor, and the requirements (ability to consume feed) are different in cows vs. pregnant heifers. They generally should be kept in separate groups so the heifers can get their share without being bullied by the older cows, or fed a supplement with higher protein level.
In late gestation, protein is a primary concern.
“Even if cattle are on winter pasture, it doesn’t cost much to sample what they are eating to determine a baseline level of nutrition and whether you need to supplement.” — Jeremy Martin
“We recommend pricing protein supplements on a cost-per-unit-of-crude-protein basis and looking at this on a dry-matter basis, particularly with liquid supplements. This makes the best comparison,” Martin says. “Alfalfa hay is usually competitive in price, if available. In some areas distillers’ products and soybean meal are feasible options.”
He adds that whole soybeans may be competitive on the basis of cost per pound (lb.) of crude protein in some years. It often comes down to availability and freight costs, or ability to handle and feed a certain type of supplement.
“Soybeans look cheap in central Nebraska, but there are not many grown in western cow country,” Martin observes. “Depending on freight and whether you are set up to feed them, they may or may not work.”
When comparing and deciding on a protein supplement, it should be at least 18%-20% protein, he advises. “Below that, it’s hard for that product to compete as a supplement because it requires so much volume that it won’t be cost-effective.”
With pregnant heifers, energy also becomes a concern earlier in gestation.
“It’s always a concern in late gestation, partly because of the greater need for energy to keep these heifers growing, and partly because they may not be able to consume enough forage, in a range situation, for fetal growth,” he explains.
“For spring-calving cows, fall is the time to assess body condition and make any changes in feed if needed,” Martin recommends. “Early in gestation it’s simpler to make changes in a cost-effective way. You have time to pick them up before their needs increase. Requirements for fetal growth are not so great yet. There are maintenance requirements that must be met before you can make any gain in body condition, and those are lower than they will be later.”
It all depends on when the cows start calving, and how much time you have left to bring them back to proper body condition if they’ve lost weight.
“Even if cattle are on winter pasture, it doesn’t cost much to sample what they are eating to determine a baseline level of nutrition and whether you need to supplement,” he says.
A common practice is to supply about 2 lb. per cow daily of distillers’ grains or cake (cubes/pellets), which are usually 25%-30% crude protein (CP).
Protein is necessary for the ruminant animal to digest mature forage because it is needed by the rumen microbes that break down and digest fiber, but it doesn’t need to be supplied daily. A person could provide it every other day and double the amount.
Ruminant animals can recycle some of that nitrogen (N) back to the rumen, but they need at least 7% CP in the diet. If forage is lower than that in protein, cattle decrease their intake unless they are supplemented — because digestion slows, and they can’t eat enough to maintain themselves, so they start losing weight. Pregnant cows need adequate protein, not only to provide for the growing fetus, but also so they can eat enough and have enough energy from the forages they consume.
Editor’s note: Heather Smith Thomas is a freelance writer and cattlewoman from Salmon, Idaho.
