by: Stephen B. Blezinger
Ph.D., PAS

Part 1

Most producers know that a major part of any cattle production program is nutrition. Nutrition is the foundation upon which virtually everything else is built, it affects growth, reproduction, health. Without proper nutrition a vast number of body functions and processes do not occur as required. For any given animal this starts at conception, where the fetal nutritional program is dictated by how the dam is fed and managed. This continues through birth and through weaning although as the calf grows and begins grazing on its own, the dam's nutrition becomes less of an influence.

A major portion of the cow's life if based on forages and roughage. As a ruminant the bovine animal is designed to be able to consume and digest fibrous materials that other species (monogastrics such as pigs, chickens, people) cannot. From this forage base, the cow can extract a large amount of many of the nutrients she requires to be productive and healthy. How much nutrient the cow can extract (digest) from a given forage source depends on a number of factors. How well this particular source meets the animal's requirements also depends on several factors. As producers and nutritionists, we are concerned with matching these two items with the goal in mind of meeting the cow's nutrient requirements in the most effective, cost efficient manner possible. Obviously, most producers are not in the cattle business to lose money. It may be a hobby to them but at the very least any producer would want to at least break even. This is on top of the understanding that the same producer would want to keep his animals healthy and productive. But, as mentioned, cattle operations take significant dollars to operate and CAN be profitable and a source of revenues for the owner if managed properly.

So back to the matter at hand – meeting the animal's nutrient requirements as effectively and efficiently as possible and in the most cost effective manner possible. So for any forage base over any given period of time for cattle in a particular stage of production, the likelihood is good that supplemental nutrients have to be provided. These may be protein, energy, minerals and vitamins. Over the next few weeks we'll discuss how to go about evaluating how to effectively supplement the cow herd in the most effective manner. We'll evaluate options and considerations and how to “weigh” the costs.

Some of the Variables

There are two primary variables that we have to identify in order to coordinate the proper nutrient supply to the animal. Initially, we have to look at the animal itself. Nutrient requirements depend on a variety of factors. These include:

1) Type of animal – cow, calf, growing heifer, growing bull/steer, bull, etc.

2) What stage of production – newly calved cow nursing a young calf getting ready for rebreeding, late second trimester bred cow nursing a big calf, pregnant heifer, mature bull, etc.

3) Breed – Angus, Brahman, Simmental, Charolais, Hereford, Limousin, Cross Breed, etc.

4) Age

5) Stress level – cold, wet, hot, muddy, transportation, handling, etc.

6) Health – Health and Nutrition are “connected at the hip” so to speak. An animal in poor health is challenged when attempting to bring them back up to a proper nutritional stage. Animals on a poor plane of nutrition will be health compromised at some point. It can become a vicious cycle.

7) Environment – this can relate to stress levels but from a big picture stand point, cattle raised in the hot dry conditions of the southwest will have different requirements than animals raised in the cooler, wetter, snowy conditions of the upper Midwest and north east.

Defining and identifying the animal's requirements is a long studied and debated topic. Only in relatively recent years have we developed mathematical models that help us develop values for the various nutrient requirements that factor in these variables to at least some degree. The National Research Council in the Requirements for Beef Cattle (2000) provides extensive discussion and references in an attempt to provide at least some sort of baseline for these values. It can be assumed that while the numbers and models that are presented in the Beef NRC are well theorized, researched and referenced, given that we are dealing with a biological entity, these numbers are at best, a calculated guess and should be regarded as such. This body of work is a very good starting place but the producer should keep in mind that the animals within his operations may differ at least to some degree from these values and calculations. As we work though this topic, we will attempt to give the reader a baseline to work with and then the resources for fine-tuning the program.

The second variable that the producer has to consider is his forage base on an annual (and beyond) basis. Since there are no forages that can be produced year-round it can be assumed that forage quality (nutritional density and digestibility) changes over the course of a year. These changes are marked by:

1) Plant species or variety

2) The season of the year and the concurrent growing periods

3) Lifecycle of the plant.

4) Management

a. Fertilization

b. Tillage or other soil/plant modifications

c. Grazing or harvest patterns

5) Environmental conditions

a. Moisture/precipitation patterns

b. Temperature changes

c. Degree of cloud cover

But what we see, in general, is the ongoing change in nutrient provision by the forage base as compared to the nutrient needs of the animal is a constantly changing dynamic. In other words, at some time the forage base meets the animal's requirements and at other times it does not. If we are truly concerned with efficiency and productivity, our focus has to be maintaining an ongoing awareness of this dynamic and how it needs to be managed over time.

Start with Something Simple

The intent of this article series will be to take an in depth look at supplementation management. However, for the moment, let's start with something relatively simple to help make the initial point. One of the most commonly discussed nutrients that requires supplementation is protein. Before we get into protein supplementation, let's take a refresher of some basics.

For years, the most common question asked when scrutinizing virtually any nutrient source, be it forage or supplement was “what's the protein content?” This is still true on many operations, especially those that adhere to the “that's the way we've always done it” school of cattle production. What is protein anyway? Protein is a nutrient required for various functions in the body including growth (muscle and bone development, fetal growth, enzyme production, tissue healing, etc.). What makes it unique is that it is made up of smaller components known as amino acids and that these molecules include nitrogen (N) in their make-up. On an average, a protein contains 16% N. A common way to analyze for protein in a given feed or forage is to analyze for the N content and multiply this number by 6.25. This will give you the approximate protein content of the material to be analyzed. This N inclusion is relatively unique to proteins since we generally do not find N in starches, fibers or fats unless they are bound to or interlaced with a protein in some way. What is more unique about proteins is that in the complex digestive system of the ruminant animal (cows, sheep, etc.) different proteins are digested in different areas in different ways and at different rates of speed. For optimum production we need to match the types of protein to the animal at its given phase of production.

Types of protein we typically refer to crude protein (the most common designation for beef cattle producers), degradable protein, soluble protein and undegradable protein. Crude protein is a general, all-inclusive term for the protein content of a given feed or forage. It includes all the protein as determined by laboratory analysis. It also includes all of the other types of protein mentioned above. One thing that needs to be noted is that crude protein is a very general term and does not take into consideration digestibility or other factors of concern. Just because a supplement (a range cube, for instance) contains 20 percent crude protein, we cannot assume all of this protein is available to the animal. This will be one of the first values listed under the guaranteed analysis on the feed tag.

Degradable protein (DP) is that fraction of crude protein which is broken down in the rumen by the ruminal bacteria. As feeds and forages are fed to cattle, the first of the four stomach compartments that the material enters is called the rumen. It is basically a large (in a mature cow the rumen can have a capacity equal to a 55 gallon drum) fermentation vat. The rumen is home to countless microbes (bacteria, protozoa, fungi, etc.) and it is this microbial population which begins the early stages of the digestive process of this material. The microbes attach themselves to the feed and forage particles and begin breaking down these particles. They then begin consuming the nutrients and incorporating them into their own bodies. This is what happens with the protein in a feed or forage particle, a potion of it is consumed by the microbes - not all but a portion. This differs with depending on the feed ingredient or the forages. The portion of the protein consumed by the rumen microbes before it leaves the rumen is considered the degradable protein. You will also see this referred to as degradable intake protein (DIP), ruminally degraded protein (RDP) as well as other terms attempting to describe this process.

Undegradable protein (UP) is a fraction of the crude protein that is not broken down in the rumen. Undegraded protein is also known as by-pass protein since it by-passes the rumen and is not subjected to microbial action and subsequent digestion. As such, it arrives at the small intestine of the animal relatively intact.

A portion of the degradable protein which is receiving a lot of interest in recent history is referred to as soluble protein (SP). This is the portion of the degradable protein which is broken down by the rumen microbes in a very short period of time upon entering the rumen. It is considered to be the protein fraction immediately available to the microbial population. Once again, this number varies depending on the type of forage or feed ingredient. This is compared to the fraction of protein that is still available to the microbes but it takes longer for them to breakdown and ingest.

Practical Considerations – Protein Supplementation

Keeping the aforementioned in mind we know that given the variables we have discussed, though out the year we will need to supplement protein to the cow. The amount we need to provide may differ at different points in time.

Supplementation also requires that not only do we need to provide critical nutrients but this must be performed in a manner that is practical to the producer. Additionally, it is entirely feasible to supplement more than one nutrient in a given form. More about this later. Let's discuss the protein supplements.

1) Commodities – all commodities contain some amount of protein, some considerably higher than others. Those with a higher protein content (35 percent or greater, as-fed basis) and generally considered protein supplements include:

a. Soybean meal - high, 48 percent and low, 44 percent protein. There are other variations as well.

b. Cottonseed meal – 41 percent

c. Canola Meal* – 38 to 40 percent

d. Sunflower meal* – 42 percent

e. Linseed meal* – 38.5 percent

f. Peanut meal* – 48 percent

g. Corn Gluten Meal – 42 percent or 60 percent

h. Dried Distillers Grains – 28 percent or 39 percent

i. Fish meal – 62 percent

j. Bloodmeal – 82 percent (non-ruminant – porcine or poultry)

This list is not all inclusive and it must be understood that all of these are by-products, i.e. they are the resulting product from processing a given grain or oilseed. Other by-products listed include fishmeal from the processing of fish or bloodmeal from pork or poultry processing. No ruminant products can be fed back to a ruminant animal. Any of the grain or oilseed by-products are variable to some degree in their nutrient content and this must be considered when using as a protein supplement


This begins our discussion of supplementation decisions and considerations to manage the nutritional needs of your herd. As mentioned, over the next few issues we will discuss this topic in great detail in an effort to provide practical guidelines for the cattleman as he evaluates his program and looks for the most practical and cost effective methods to provide for the nutritional needs of his herd. In the next issue we will pick up with our discussion on using commodities as protein supplements.

Dr. Steve Blezinger is a nutritional and management consultant with an office in Sulphur Springs, TX. He can be reached by phone at (903) 352-3475 or by e-mail at sblez@verizon.net. You can also follow us on Facebook at Reveille Livestock Concepts.

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