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

Part 3

In the first two parts of this series we began discussing some of the intricacies of managing a nutritional program for the purebred cow herd. It should be stressed that that the various areas of discussion would also apply to the commercial breeding herd. The main difference is that many purebred herds will develop both heifers and bulls out to breeding age or at least close to it and subsequently need a growing and developing program for these as well as a general nutrition program for the cow herd.

In developing the overall program one of the primary factors to deal with is balancing nutrient supply with nutrient demand. In the last part of this series we discussed the many variables that come into play when we are working on nutrient S&D (NSD). Let's review these briefly. On the demand side, factors that affect nutrient demand include:

1) Stage of production

2) Age of the animal

3) Breed

4) Frame score

5) Milking ability

6) Sex

7) Stress level

8) Health

9) Environmental conditions

10) Season of the year

Another factor that can be added to this list is exercise level given pasture type and size as well as terrain, as this can contribute to caloric demand. In other words, cattle on these types of pasture, particularly if they have to travel longer distances, will need to consume more calories in order to maintain the same body condition.

On the supply side of the coin, variables that come into play include:

1) Forage base. This includes:

a. Grass type(s)

b. Fertility, fertility program

c. Grazing management (cross fencing, pasture rotation)

d. Moisture levels, timing

e. Stored forage program (hay, silage, stockpile forage)

2) Supplement program. This includes:

a. Type (protein, energy, mineral, combinations, etc.)

b. Frequency of supplementation (constant – self fed, periodic)

c. Feeding rate (how much per head per day)

3) Water source and availability

Some Strategies

Producers I work with often are concerned with where to start building the nutritional program, on the supply side or on the demand side? While the important factor is that you START to begin with, it makes the most sense to start on the demand side. From an ongoing program perspective, long term, the basic, total nutrient demand is potentially a more stable, less variable and more predicable number than the supply side of things are. Nutrient demand CAN be quantified while supply can only be estimated. The only exception to this might be if the operation feeds a significant amount of harvested, stored forage AND tests this supply extensively. There will still be some assumptions that have to be made concerning the total supply given the nutrient variability within a given field that is harvested that cannot be accounted for. We can't test each bale or ton of silage. We can, however, come fairly close in calculating a total nutrient demand for a given group of cows based on current equations available to us.

Estimating Demand

When possible it is always best to group cattle by age and production status as tightly as feasible. This works most effectively when a given herd is on a controlled, tight breeding season particularly a 60-90 day interval. These cows can be grouped by breeding stage or pregnancy status and can be supplemented accordingly. This requires a lot of cross fencing and some fairly intense management but the benefit is that the animal is on a more accurate nutritional plane and thus potentially will produce more efficiently.

Operations do not get to this point overnight. It does take a lot of management and it takes a lot of study on the producer part to understand what the cow's nutrient requirements are at any given stage of production and how these requirements can change based on the variables shown above. Let's talk about a scenario or two. We'll start with grouping by production phase and age. These groups might even be focused in terms of the pasture they are in – whatever makes the most sense to the producer. In other words, the descriptions might include a dry cow pasture, calving pasture, breeding pasture, growing pasture or similar.

For the breeding herd on a 90 day spring calving cycle, in a perfect world we will group as follows:

1) Bred, dry (no suckling calves), last trimester of pregnancy

2) Newly-calved cows up to 90 days post calving. Breeding period includes bulls.

3) 90 days post calving through weaning (six - seven months post calving).

If pastures or traps are available it would also be useful to have a group/pasture between Groups 1 and 2. This pasture might be used for calving (move big pregnant cows into the pasture as they are about to calve and leave them there 30 days post calving. Once they are at 30 days post calving they are then moved to the breeding pasture where they are put with the bulls, begin an A. I. program, etc.)

This system would be employed year after year and will become a normal process after adaptation. It will require some fairly extensive record keeping. It will require cows and calves to be individually identified and it would require (for most producers) attention to an even or moderate temperament. Cattle that are “spookier” may not adapt well to the regular handling and movement.

Another potential downside is the social re-adjustment when moving from one pasture or pen to another (from one group to another). Any time new animals are introduced into a group an adjustment period must take place for the new social or “pecking” order to be established. This is common in the dairy industry where cows are moved from one production group to another fairly frequently.

Again, for the producer, this may take some time to adjust to as well if not already used in the operational management program. A second complicating factor is if the operation utilizes a rotational grazing system of any type. This is strongly recommended as it gives pastures time to rest and for forage regrowth to occur.

The biggest benefit is that each group has a fairly consistent set of nutrient requirements and that with time, calculating the differences between the groups daily demands compared to the pastures daily supply will become reasonably simple. While daily calculation of nutrient needs is unnecessary, longer periods (biweekly, monthly) will be of value, particularly during periods when forage quality and quantity are changing rapidly. A nutritionist can help you calculate what the specific requirements for a given production group are and provide suggestions and alternatives for needed supplementation to meet the requirements at any given stage of production. For the more ambitious, obtain a copy of the most recent Beef NRC (National Research Council) which provides extensive information on not only the basic animal nutrient requirements but also the adjustments that should be made for many of the variables discussed previously.

Other suggested groups that need to be established and maintained include:

1) Developing Bulls – young – weaning to 12 months

2) Developing Bulls – older – 12 months to sale age

3) Developing Heifers – young – weaning to breeding

4) Developing Heifers – breeding to calving or to sale age.

5) Breeding bulls – when separated from cows.

This is only one potential production scenario and is relatively complex utilizing 8-9 groups. Some operations simply do not have the land and pasture resources for this level of grouping and that is perfectly fine. Other possibilities are easily developed and managed. The point here to emphasize is the more focused these groups can be, the easier it is to fine tune the individual components of the nutritional program and subsequently increase performance and economic efficiency.


As always, the goal here is to give the producer food for thought on how to become more productive and more profitable. Since nutrition is such a major part of what it takes for the animal to be healthy and productive, understanding ways to manage the nutritional program and all the individual facets are exceptionally important. In the final part of this series, we will discuss managing the supply side of the program including tools for making supplementation decisions.

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 For more information visit Livestock Concepts.

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