Cows require different nutritional levels at different stages of gestation. Nutrient requirements in early gestation are not much different from maintenance requirements, but as the fetus grows larger the cow’s nutrient needs increase. And if a cow is lactating, she needs a much higher level of protein and energy than when she is pregnant.
Protein requirements for pregnant cows increase during later stages of gestation, and are even higher for young cows. If you are keeping the young cows (the ones that will be first and second calvers) separate from the main herd, they can be supplemented with protein, if needed, without having to supplement the whole herd. The mature cows can be roughed through winter and early spring a lot easier than younger cows, because they are not trying to grow.
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Ruminant researcher Dr. Tim McAllister at the Lethbridge Research Centre says protein requirements are fairly low in the fall for spring-calving cows, around eight per cent. “They can live on fairly poor forage at that time, and fall pastures are generally adequate until they get further along in pregnancy. Then it’s just a matter of supplementing with better-quality hay. The level of protein never has to be higher than about 12 per cent, which they would need right before calving. High-quality grass hay, or a grass/alfalfa mixed hay would be ideal for cows in late-stage gestation. Cows are very efficient in their utilization of nitrogen,” he says.
“If the fall pasture forage is low on protein you can extend the use of their pasture with a protein supplement. If pasture quality is fair, you can extend their grazing just as much by using an energy supplement (like a pellet) since liquid protein supplements are pretty expensive. You can supplement with an energy pellet at the rate of a couple of pounds per head per day. This can be more economical and encourage them to keep using the dry pasture,” he says.
“The thing you have to watch out for in this situation is the boss cows eating more than their share. You could end up with some fat cows and some thin ones. One way to deal with this is to break the herd up into smaller groups, putting the younger cows separate from the older cows,” says McAllister.
“Protein levels in most forages are generally adequate for dry cows in early to mid-gestation unless it’s very poor-quality pasture like barley straw — where the protein level might be only five per cent or so. Otherwise you won’t encounter deficiency,” he says.
They do need an adequate level of protein to “feed” the microbes in the rumen that break down forages into usable nutrients and get the energy benefit from dry feeds like mature grass or even straw. “This is where the nitrogen has an important effect, and why you must have enough, because it is used for microbial activity,” he explains.
Come winter, Dr. Bart Lardner at the Western Beef Development Center and adjunct professor in the department of animal and poultry science, University of Saskatchewan, says producers are always looking for ways to bring protein to the animal as cheaply as possible. “Feeding a legume hay would be ideal, at so many pounds per head per day to meet protein needs at that stage of their pregnancy or lactation.” But if good legume hay isn’t available barley, oats, wheat can fill the gap, depending on whether they are cost effective.
Another option in the past 10 to 15 years has been the byproducts of the ethanol industry, depending on the plant’s location. “Location is everything,” says Lardner. “If trucking fees aren’t limiting your ability to bring that product to your operation, the protein content of that byproduct is typically three times what the original wheat or corn commodity was.
“These byproducts come in different forms, however. It may be marbled or flaked and might be hard to feed to cows, especially out on pasture. You need to know the form or structure of that protein supplement coming as dried distillers grain (DDG) plus solubles.
“There are other protein sources such as hull products (pea hulls or oat hulls). They may not be as high in protein and may be higher in fibre, but will certainly add to the protein in the diet to meet cows’ requirements. They may not be as good as alfalfa hay, cereal grains or DDG but are some possibilities to look at,” says Lardner.
After you’ve located a protein source, the next question is how to get it to the cows. It may be a portable feed bunk or just putting it on the snow or ground. “We’ve looked at some alternatives here, and found we could feed the grasser cattle protein supplement on alternate days and didn’t have to take it to them every day. We were able to reduce labour costs 20 per cent.”
Other studies have shown that alfalfa hay can also be fed every other day, during the winter.
“Some people are trying to build a winter ration for this coming season and we know that hay prices are a little higher because of the drought in various parts of the country. The first step is to do a feed test on all the available feed sources, whether it’s straw or poor-quality hay, or whatever is in your feed yard, as a starting point. Then look at the cows’ requirements in terms of when they are going to calve. Then you can build an adequate supplementation program throughout the winter,” he says.
Protein sources
Alberta beef and forage specialist Barry Yaremcio says distillers grains and byproduct feeds such as canola meal or soybean meal, provide anywhere from 36 to 48 per cent protein.
“Distillers grains can be a less expensive way to supplement. The thing to watch for with distillers grains is the high phosphorus content — about three times higher than what you find in regular grain like wheat, barley, oats, etc. Thus the calcium-phosphorus ratio will be affected, and additional calcium may be needed. You need to watch the calcium and magnesium levels in the ration,” he explains.
Another protein source is feed peas. Peas contain 24 per cent protein and are an excellent source of energy, about the same as barley.
Feed-grade urea is another option. For cows to use urea efficiently, three or four pounds of grain should be fed per head daily. “Cows need the soluble carbohydrates in order to use the urea,” says Yaremcio.
“If you are using urea in a ration, no more than 25 per cent of the total protein should come from urea. The reason is that when we look at plant protein, there is always a certain amount of sulphur tied in with the proteins in forages and cereal grains. The nitrogen-sulphur ratio is important. If you have too much urea in the diet, it is possible to have insufficient amounts of sulphur. Then the rumen bacteria cannot rebuild the amino acids. Reduced levels of amino acids available to the animal limit the amount of tissue growth or milk protein production,” he says.
“Protein lick tubs are sometimes used, to improve the amount of protein in the diet when cattle are grazing late-season dormant forages. The caution is that it can be very expensive. Determine consumption rate per head per day and what it is costing.” The disadvantage to free-choice consumption is that there is no control
over intakes.
Meeting nutrient requirements, especially protein, is essential to maintain an efficient and productive herd. Feed testing is crucial. “When you get the results, you can use a ration-balancing program such as CowBytes (available from Alberta Agriculture and Forestry) to avoid unwanted problems and unnecessary costs. If a producer has questions regarding proper supplementation and balancing the diet for pregnant or lactating cows, talk with a feed mill nutritionist, government extension person or private consultant who can give advice on how to adjust the feeding program when using unusual or multiple feed sources.”
