Protein Supplements May Be Needed for Mature, Dry Forages

Published on Mon, 07/26/2021 - 9:12am

Protein Supplements May Be Needed for Mature, Dry Forages.

 By Heather Smith Thomas.

 In fall and winter, most pastures are low in protein (unless fall rains stimulated new growth).  Many stockmen extend grazing as long as possible into winter because winter feeding is the most expensive aspect of raising cattle.  Adding protein supplement to mature, dry pastures is generally cheaper than feeding a full ration of hay.  The cattle continue to harvest their own feed (grazing) and less hay needs to be put up or purchased.  Even a fairly expensive protein source is often cheaper than feeding hay.

Adequate protein level in the ruminant diet is crucial for optimal microbial growth and function.  Rumen microbes transform the complex carbohydrates present in dried standing forage so the animal can utilize them.  Cattle often lose weight on dry pastures, when they should be building reserves in preparation for winter and next spring’s calving.  Without protein supplementation on dry pasture, the rumen cannot adequately digest the low-quality forages.  Supplemental protein, whether supplied with alfalfa hay, cake, blocks or tubs, or by-products like distillers grains, improve digestion of low-quality forages.  

David Bohnert, Beef Extension Specialist and Ruminant Nutritionist, Oregon State University (Eastern Oregon Agricultural Research Center, at Burns, Oregon), says producers should minimize use of harvested forage.  “But in some mountainous and northern regions, depending on the year, you’ll still have 2 to 5 months of feeding hay.”  There might be years that you have several months’ good stockpiled pasture available but deep snow makes it unavailable.

“This is why you need some hay on hand (or a neighbor with extra hay who will sell some) as a backup plan.  But if it’s an open winter, we can often let the cows graze well into the winter,” he says.

“To do that, we need to know the forage quality. You could clip a representative sample of what the cows are eating, to test protein content—and also NDF/ADF and minerals if you are concerned about those.  You need to know if you need a supplement, and how much.  You don’t want to underfeed or overfeed a supplement.”  You are wasting money on a supplement if the protein level is adequate in the pasture, or if you overfeed a supplement when a lower level will do.  If nutrient level of pasture forages is inadequate for expected performance, you are hurting production and body condition if you don’t provide a supplement.

Though it’s not a substitute for a forage test, you can monitor appearance of cattle feces.  Many ranchers and nutritionists can tell whether the cattle have adequate protein by the manure.  If feces are loose, this is a good indication that cattle have adequate protein to feed the microbes to aid digestion and keep material moving rapidly through the digestive tract.  If feces are hard-packed and dry, this means the material is moving too slowly; there’s probably not enough protein for optimum function of rumen microbes.

“This is a crude measure of nutritional quality of the forage, but it’s a clue,” says Bohnert.  If feed is not digested quickly enough, it stays too long in the rumen, and the cow can’t eat enough because she’s already full.  If this situation continues very long she loses weight because she can’t process enough feed to maintain herself.

Visual appraisal of cow body condition is another clue.  It’s good to go through the herd and write down body condition scores, or take photos.  This gives you something to compare, as you go through fall and winter, to determine if cattle are holding their own, losing weight, or gaining.  “If they lose weight late in the season it gets harder to put it back on, during cold weather,” he says.

“If the cattle need more protein (if you observe feces becoming firmer and stacking up), you need to do some educated guessing on how much forage the cattle are eating.  With cool-season grasses they may be eating 2% of body weight in dry matter.  If it’s a 1000-pound cow she’s probably eating 20 pounds; if it’s a 1200-pound cow she’ll be eating about 24 pounds.  If you can estimate forage intake is, and know the protein content of that forage, we can look at nutrient requirements of those cows to determine if they are short of protein, and how much we need to feed,” he says.

“Then we decide what to use and how to feed it.  It might be alfalfa hay, or a loose mix in a feed bunk, or a block or tub.  It may depend on whether we can drive to those cows with a feed truck or tractor,” says Bohnert.  In rough terrain the best option may be blocks or tubs you can take out there with a 4-wheeler.

There are many kinds of protein sources.   “The choices boil down to what is economical and available (without high freight cost), and how you are going to feed it.  You might talk to your Extension agent or someone who can help you figure it out. With blocks or tubs it can be hard to meet their requirements, but even if we provide a little protein this can help.  Another aspect of using blocks or tubs is that we can often affect where cattle graze—and entice them into areas they might not use otherwise.  Many extensive pastures are only being 50% utilized by the cattle.”  There might be forage on terrain the cattle aren’t getting to, and we can attract them into those areas with protein.

Getting the right amount of protein intake will help the cattle utilize/digest that forage.  Some cattle may not have as much access to blocks or tubs, however, if dominant individuals keep the timid ones away.  In big range pastures, cattle may graze and travel in groups, and all come to water or to the protein tubs the same time, which means the bossy individuals get the most chance at those.  In range areas with major predators, cattle tend to stick together as a herd, or several small herds.  This is their natural tendency, as a prey species.  It’s only been with domestication that cattle have developed more individual grazing patterns.

“In a winter grazing situation, if there are large predators like wolves, this may affect how well the cattle do or do not utilize certain areas.  They stay grouped and probably don’t graze as much as they would without the predators’ influence,” he says.

“How you handle them is also important.  Knowing how to move cattle to certain areas and encourage them to stay in those areas is crucial.  Supplementation is only one of the tools we can use.  Herding and stockmanship can also make a difference.”  When you put the tubs or blocks in a certain area, hoping to encourage cattle to use those areas, you need to get the cattle there so that they know the protein is available.

“Winter grazing is great, but you don’t want to hurt body condition scores. We are always fighting that drop in nutrition.  Our research has shown that supplementation to increase body condition during mid-to-late-gestation is important.  If we can increase body condition during that time we get a positive effect on the calf, and the calf’s future productivity, compared to supplements during early gestation or just holding them at a certain level the whole time.  Cow body weight fluctuation can have a positive effect and we are still learning more about that as time goes on,” he says.

Season of calving makes a difference, too, whether the cows on winter pastures are lactating, dry, or in early or late gestation.  “Spring-calving cows can probably do fine with modest protein supplementation—whereas fall-calving cows need more nutrients for lactation,” he says.

If cattle are in an area you can get to with a tractor or truck to feed alfalfa, this may be a good protein source, since it doesn’t need to be fed every day.  “You can feed alfalfa every 2nd or 3rd day or twice a week.  Feeding a supplement like cottonseed cake or cubes can even be done once a week, with acceptable results.  Ruminants can recycle nitrogen when eating low-quality forage.  When consuming protein-deficient diets, their body is geared to conserve as much of the protein and nitrogen as they can. With a high-protein meal (cottonseed cake or high-quality alfalfa) they will recycle some protein back to the rumen, to make the rumen happy by keeping the microbes functioning optimally for digesting the low-quality forage.  This is the main objective when we supplement low-quality forage,” Bohnert explains.

“This is how ruminants evolved, to take advantage of periods when they had access to higher-quality proteins, when ordinarily all they could find to eat was low in protein.”  They could consume higher-quality forages and utilize the protein over a longer period of time (2 to 7 days), until they found something else to eat that was high in protein again.

We can take advantage of the rumen’s nitrogen-recycling.  Feeding a supplement like alfalfa or cake once or twice a week versus every day, saves money and labor.  “This might be logistically difficult, however if you are trying to feed a large number of cows.  That’s where the blocks, tubs or lick tanks can be helpful,” he says.

Most producers now understand that the reason we feed protein in the first place is to “feed” the rumen microbes and enable them to multiply adequately for optimal digestion of forages.  “If we make the rumen happy, with enough nitrogen, minerals and water to handle the carbohydrates that are already there in the forage, the animals will be happy.  They can maintain or improve body condition simply by having that correct balance in the rumen,” says Bohnert.  Low-quality dry forages are adequate when there is enough protein added to facilitate digestion, and the fermentation/digestion of these forages generates heat and can help keep the animal warm during winter.  

Hay Feeding Tip In Cold Weather
Another consideration when feeding harvested forages during winter is timing of feeding to take advantage of the heat of fermentation.  “If you are feeding hay, increase the amount of low-quality hay if you know you’ll be having a cold spell.  I like to feed late in the afternoon.  This keeps the rumen full and fermenting (generating heat) through the cold night.  Many ranchers or cowboys want to feed early in the day, but that means most of the heat of fermentation (that keeps the body warm) is occurring during the day when the sun is up.  Cattle need it more during the long winter night!  If we wait until afternoon or evening the cows will stay busy eating and be full and warmer.  They still get the same amount of feed whether you feed them in the morning or the evening, but they get more benefit from the heat of fermentation if you feed them late in the day,” he says.