As we continue through autumn, many readers will understand that fall forage dormancy and winter snow cover are key times when we can expect energy deficiencies. Drought, overgrazing, grasshopper infestations and many other events could be on your local list of potential forage energy-deficiency events.

Some cattle producers feel energy supplementation is not a cost-effective management practice. They want to see their cattle working for them and turning grasses and forbs into pounds of beef with little to no interference from the rancher or checkbook.

A respectable goal, yet there are years of economics research and standardized performance analysis (SPA) data that has been collected on cattle operations across the nation which suggest that ranches investing in modest input expenditures can improve cattle productivity when compared to ranches where inputs are restricted to the absolute bare minimum.

Decreased conception rates among cows, reduction in daily milk yield and lactation period, loss of bodyweight, reduction in fetal growth and lowered resistance to disease, parasites and toxic plants are just a few of the ways that an energy-deficient diet can negatively impact a cattle operation and a ranch’s profitability. This is one of those paradigms when you may actually lose money by trying too hard to save money.

The variety issue

Nutrition concerns related to a forage-energy deficiency can be complex. The simple solution is often to supplement with an energy-type supplement which is low in protein and high in energy. These can range in a variety of forms: liquid supplement tanks, energy tubs or blocks, range cubes or grass hay. They can also sport a wide range in costs, leading to the idea that energy supplementation is too expensive.


Before making your selection, consider what the cost of the supplement is by the unit of energy as opposed to the cost per ton of supplemental feed. After all, if you have made the decision to purchase a supplemental feed due to a limiting factor in the diet (in this case, energy), you should be confident that the economics of that purchase work to overcome the limiting factor you are trying to correct. This can help you control the input expense as well as limiting overfeeding of the supplement.

Weighing TDN

Along with cost factors of the feed, producers may want to give some consideration to how they determine the feeding rate. Many of us use the total digestible nutrient (TDN) system to determine energy value. This system has been around a long time, and cattle producers throughout the nation have grown accustomed to it. The numbers are relatively simple to understand, remember and calculate.

Unfortunately, the TDN system doesn’t have the accuracy of some other energy calculation systems. The mathematical formula used to derive a feedstuff’s TDN has a potential to report high-fat feeds as more than 100 percent TDN. Perhaps more notable, the system does not consider energy losses through urine, gases or heat given off by the animal. Only digestive losses are considered.

Along with this, roughages are over-valuated in the TDN system. High-fiber feeds, such as forages, give off more heat when broken down, and as just mentioned, heat losses are not measured with this system. Many scientists will tell you energy value would be more accurately represented as megacalories (Mcal). For this reason, the net energy (NE) and metabolizable energy systems are growing in popularity. It is possible to have a 1.2-pound sample of corn providing 1.2 Mcal of NE, 2.1 pounds of a high-quality hay giving 1 Mcal of NE and a 2.4-pound poor hay sample valued at 0.8 Mcal NE, while all three feed samples are valued at 1 pound of TDN. This may appear to be a small difference, but when applied to a herd of cows over multiple months of feeding, a more accurately calculated ration may save a few dollars.

Delivery options

You also need to give consideration to labor costs, available time and delivery options. Many ranchers will ignore these costs, but they should be included in the input decision process. When the economics of these factors are combined with the feedstuff’s unit of energy cost, it may change the outcome of your purchasing decision.

As an example, quality hay often has a lower unit of energy cost than does an energy tub or block. This may make hay the more reasonable energy supplement for the cow herd behind the barn. However, the energy tub or block may prove a more viable option for the cow herd you drive 60 miles to see once a week.

Another reason energy supplementation is often seen as cost-prohibitive is due to a substitution effect. This can occur when grazing cattle are provided a high-starch energy supplement. These tend to be energy-dense and a cow will reduce forage intake by 0.5 to 1 pound for each pound of energy-dense feedstuff she consumes.

Additionally, forage digestibility in the rumen can be reduced when high starch levels are in the diet. Substitution effect can also occur when feeding large amounts of hay where the rumen fills with hay instead of grazed forage. If the hay is of low quality, it may do no more good than the grazed forage. Why pay for a feed that is going to be of relatively equal value compared to what is standing on the rangeland?

Intake considerations

The input-conscious cattle producer may discover that the simple solution to a forage-energy deficiency does not fit in the ranch’s profit-and-loss spreadsheet. A more complex solution may benefit these producers.

These producers need to determine what the root cause of the energy problem is. Fortunately, it will often come down to a couple of intake problems. One of the primary intake issues is triggered by a low level of crude protein in the forage. When the crude protein levels of consumed rangeland forages drops below 6 to 7 percent, forage intake will drop also.

The rumen microbial population needs nitrogen to survive and function; they get that nitrogen from the protein in feedstuffs. Therefore, adding a protein supplement to the diet can increase forage intake in many cases and alleviate or reduce the energy deficiency problem.

Numerous research studies suggest that rangeland forage intake can be increased 20 to 60 percent, and digestibility can be increased by 5 to 15 percent by utilizing protein supplementation. The protein supplementation can also help in fetal growth and cow performance, leaving many producers to believe it is a more cost-effective solution than energy supplementation.

Another intake problem occurs when forage digestibility decreases. This can have an effect on the rate of passage through the animal, dramatically lengthening the time between consumption and expulsion. This allows the rumen to fill with forage, and the animal can no longer consume more forage until some digestion has occurred.

Again, this scenario may be helped with the inclusion of a protein supplement in the diet. The protein invigorates and increases the microbial population, allowing a more rapid breakdown of the digestible fractions of the forage.

Every cattle operation has its own goals and business plan which need to be a guide when making decisions on how to handle a forage-energy deficiency. Yet the topics discussed above may provide something for producers to consider when facing this situation.  end mark

Michael Fisher is a Pueblo County extension director for the Colorado State University Extension. Contact him by email.


Photo courtesy of Michael Fisher.