Importance of Protein
for the Pregnant Cow
The biggest factor contributing to calf health is nutrition of the dam during the final three months of pregnancy, and her body condition, says Grandview, Idaho, veterinarian Dick Fredrickson. "If cows are not adequately fed during that time, you'll have more scours, respiratory disease and other illnesses in calves, and they won't do as well later."
The most important ingredient in the cow's diet, he says, is protein.
"In actuality you are not feeding it to the cow; you are feeding the rumen microbes so she can digest forage. Rumen function is critical, and we have to feed the microbes that are key to the digestion of lower-quality forage," Fredrickson explains.
"The microbes utilize minerals and protein to make enzymes that help them break down and digest forages," he continues. "The microbes and enzymes then pass out of the rumen and are digested and absorbed in the intestines, providing the cow with additional protein and minerals."
Protein can be added to the cow's diet by using a small amount of alfalfa hay, a high-protein pellet, or some other commercial protein supplement.
"Don't use urea with a low-quality forage diet, because the cow needs starch to convert urea to protein," Frederickson warns. "Low-quality roughages do not contain much starch, so the urea volatilizes and passes out of the rumen as nitrate and is excreted in urine. You wasted your money, and the urea in these situations can be harmful to the cow. There have been cases of nitrate toxicity when using urea to supplement low-quality forages."
Frederickson advises using fiber-friendly feeds for supplementing protein and energy. "High-starch supplements such as corn and barley interfere with fiber digestion. Rumen microbes that digest starches don't do a very good job of digesting roughages, and vice versa. Those microbes are actually antagonistic to one another. The rumen flora either multiplies to digest roughages, or starches, and are not in balance for the other," he says.
"Dried distillers grains' or corn gluten have the starch removed and are fairly high in crude protein, so they are good protein sources to balance a forage diet. They also have a fair amount of fairly digestible fiber," he explains.
Alfalfa hay is an excellent choice as a protein source for cows on a forage diet. "Beet pulp and soy pellets are good energy supplements because of their highly digestible fiber, but they are not high enough in protein to use with low-quality roughages as a protein supplement," Fredrickson explains.
Beef cows should consume 2.5% of their body weight in good forage. Low-quality forages (with low protein levels, such as straw, dry mature grass, cornstalks, etc.) will reduce digestive efficiency by as much as 30%.
"Cows on low-quality forage cannot eat enough to maintain body weight and develop a calf," Fredrickson says. "By supplementing so the total diet contains 7% protein, the cow's intake will increase, and she can digest the roughage much better."
A protein supplement, whether it's alfalfa hay or a pellet, can be fed every third day, just tripling the amount that's fed. "The rumen can get by on this type of periodic protein supplementation," Fredrickson says.
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