by: Stephen B. Blezinger

Part 2

In part 1 of this series we began a discussion of the numerous nutritional sub programs necessary for the production groups that must be managed to have a comprehensively successful nutrition program on a typical purebred cattle operation. One thing to be noted is the amount of variation in these programs as well as the others to be discussed in the following sections. This variation can have serious effects on the success of the overall programs if not recognized and accounted for.

Let's go through a number of these variables.

Dealing with variables in the typical nutrition program

As we have discussed in these articles before, a nutritional program is based on supply and demand. The cattle, regardless of age or production stage have a demand for nutrients in order to perform optimally. This performance is in terms of reproduction (breeding, conception, pregnancy maintenance, parturition, rebreeding), milk production, health, resistance to stress, calf growth and so on.

This brings up another question, that, for most producers is never really answered: “what is optimal production on my operation?” This is possibly one of the most challenging questions to answer because 1) a breeding cattle operation is a biological system and 2) because it is constantly changing and 3) it is subject to interpretation. What one producer considers optimal production may surpass or fall short of another producers expectations. What I typically suggest to producers is that they need to determine, based on their own experience or desires, what is optimal production for them at the immediate point in time. Once they have determined what they believe optimal production to be, then they can determine where or how they can improve. In many cases this means what can be done to improve economic performance but this is not always the case. In some situations it may be learning how things can be done to save time or effort. In other cases it may have something to do with appearances of the cattle (i.e. maintaining a body condition score of 7 or more instead of a lower score that, while adequate for good reproductive performance, allows the cattle to appear thinner).

Back to the discussion concerning nutrient demand by the animal. The following factors each have a significant effect on the nutrient demands of the animal:

1) Stage of production – Certain production levels require much higher levels of nutrient intake than others. For instance, a heavy bred, lactating cow nursing a large calf will have much higher requirements than a dry cow.

2) Age of the animal – Older cows typically have higher requirements than younger animals.

3) Breed (it is interesting to note that in many cases there may be more variation within a given breed than between breeds). English breeds (Angus, Hereford, Shorthorn) typically have lower nutrient requirements than continental European breeds (Charolais, Simmental, Limousin, etc.) and Zebu breeds. Also, crossing of certain breeds, particularly Brahman with either English or European breeds results in a certain level of hybrid vigor that may actually reduce nutrient demand or improves efficiency of performance at a specified nutrient level.

4) Frame score – higher frame scores typically have higher nutrient demands

5) Milking ability – females with a capacity for higher milk production have higher nutrient demands, particularly for protein, energy, Calcium and Phosphorus.

6) Sex – Bulls will commonly have a higher nutrient demand compared to females of the same age if the female is not lactating or pregnant.

7) Stress level – High stress levels (heat, cold, transportation, handling) results in a higher nutrient demand

8) Health – sick cattle have higher requirements. However, dry matter intake levels are commonly lower during periods of sickness. This can make providing appropriate level of nutrients to the animal challenging.

9) Environmental conditions – heat or cold, wet conditions, very dry conditions can all effect nutrient requirements, generally causing an increase.

10) Season of the year – this typically goes along with environmental conditions.

In general, these factors have the greatest effects on protein and energy (caloric intake) demands. They can also affect the macro minerals calcium, phosphorus, potassium, etc. Similar effects are noted for trace minerals and vitamins as well.

Yet another complicating factor is accurately meeting the needs of a cow herd is exactly that, you are working with a herd, not individual animals. In a herd of 100 cows you essentially have 100 individual nutritional programs. While numerous animals in that herd may be very close in their requirements, there can be significant variation in nutrient requirement with in a herd, especially when considering the highest requirements as compared to the lowest. Over time and selection hopefully this requirement variability will become less and animal similarity increases both genetically and phenotypically. However, variations in requirements still exist.

This animal nutrient demand has to be projected against the sources and variation in nutrient supply. The nutrient base for the typical cow herd is forages (pasture, hay, etc.) and in many cases a supplementation program of some type (mineral, protein/energy). Variations in the nutrient supply include:

1) Forage type (plant species).

2) Soil fertility level, soil health.

3) Fertilization program.

4) Environment – particularly moisture levels.

5) Time of the year, growing season.

6) Timing of moisture supply.

7) Grazing management – pasture rotation, supplemental forage planting (i.e. winter annuals, legumes).

8) Forage harvest, storage methods – hay production, bale type, protection of forages. (barns, covers, etc.), haylage, baleage, silage.

9) Supplementation type (minerals, meals, limit feeds, cubes, commodity mixes, tubs, combinations of any or all of these). Supplements fill the gaps at any given point in time between the nutrient supply delivered by the forage base and the demands of the animal at that same point in time.

10) Water sources – can affect mineral intake levels.

Accurately balancing nutrient supply and demand is the most challenging part of any cattle nutritional program. Managing the variation concurrently with the constant, ongoing changes in both demand and supplies are difficult in any situation, particularly when a producer is, in fact, focused on optimizing performance and economics.


Understanding the variations in both nutrient supply by the forage base as well as the demand by the cow herd is critical for the purebred and commercial producer alike in development and maintenance of a sound nutritional program. In Part 3 of this series we will cover some specific strategies for balancing supply and demand on a continuous basis.

Copyright 2015 – Dr. Stephen B. Blezinger. Dr. Steve Blezinger is a nutrition and management consultant with an office in Sulphur Springs, TX. He can be reached at (903) 352-3475 or by email at [email protected] For more information visit Livestock Concepts.

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