Forage Quantity and Quality Impact Beef Nutrition
Management of beef cattle nutrition ideally should be based on the quantity
and quality of forage, as well as animal considerations such as body
condition score, physiological status and production goals, according to
information from the Texas AgriLife Extension Service (formerly Texas
Agricultural Extension Service).*
Estimating the quality of forage consumed by grazing animals often is
difficult because the quality of forage changes seasonally, according to
beef cattle specialists. Also, in rangeland environments, animals can choose
from numerous plant species and select specific plant parts. This
selectivity frequently changes the diet composition and makes it difficult
to tell exactly what these animals are eating.
For some time, it has been recognized that a relationship exists between
forage quality and the physical appearance of feces of grazing cattle.
Grazing cattle primarily eat grasses and forbs (herbaceous broadleaf plants)
and prefer new plant growth. New plant growth consisting of mostly leaves
contains high levels of easily digestible compounds.
This new plant growth has very little fiber in the form of cellulose or
cellulose-lignin complexes. Therefore, cattle droppings that result from the
consumption of immature, high quality forages tend to fall to the ground in
relatively shapeless deposits. As grasses mature, the fibrous content
increases and the appearance of the cattle droppings reflects a lower
quality diet that is high in fiber.
To help interpret the relationship between forage quality and fecal
appearance, please see adjacent photos.
Forage quality categories are divided on a crude protein basis because this
approach provides the clearest relationship to visual changes in droppings.
Some overlap of digestibility values exists between the middle two crude
protein levels. Forage quality estimates were obtained using near infrared
reflectance spectroscopy (NIRS) fecal analysis. While this guide serves as a
general indicator of forage diet quality, more precise estimates can be
obtained through NIRS fecal analysis.
Interpreting forage quality
Forage quality must be interpreted in relation to the status of the animals
being managed. Be sure to consider these factors:
- Animal physiological status (dry, lactating,
- Body condition score for determining performance
goals. Body condition scores are good nutritional management indicators.
These scores reflect past forage quality and quantity levels, but they
also indicate future management needs.
- Production goals (maintenance versus gain).
Don’t overlook forage quantity
While forage quality is important, so is forage availability or quantity.
Beef cattle experts say there are several indicators that may provide clues
to forage availability. These include:
- Forage preferences. Even though grass is
their preferred food, some grasses are more palatable and cattle will
search for these specific grasses. Having “a lot of grass” does not
necessarily mean cattle will perform at the desired level if very little
of the desired grass is available, according to experts.
- Eating of browse. Texas AgriLife Extension experts explain that cattle
diets typically consist of more than 80 percent grass and other herbaceous
plants. Cattle are not efficient at eating the leaves of wood plants, also
known as browse. Normal diets usually contain less than 7 percent browse. If
cattle are spending time eating browse, it is a good indicator that
available forage is limited. Performance most likely will suffer once browse
in the diet reaches 10 percent.
- Grazing patterns. Cattle have fairly
definite grazing patterns. Typically, there are three major daily
grazing periods–long periods at dawn and late afternoon and a short one
near midnight. Cattle graze to fill a need for quantity. If you see your
cattle grazing in the mid-day summer heat, this might be an indicator
that they do not have enough grass to meet their needs.
Help with nutrition management
Purina Mills has designed supplemental feed products to help you manage your
beef cattle nutrition programs. These products can improve animal
performance while also enhancing forage utilization. They help you balance
the nutritional needs of your cattle when forage quality and quantity
decline as the spring and summer progress.
Three range supplements, for example, contain Purina’s exclusive Intake
Modifying Technology™. These are: Sup-R-Block®, Sup-R-Lix®, and Accuration®
Purina Mills IM Technology supplements are offered free-choice, not
hand-fed. IM Technology products are consumed by cattle multiple times a
day. This optimizes the rumen’s environment so you’re offering cattle
predictable, consistent nutrition all the time.
Other benefits of these products include:
- Cattle graze longer because they do not need to
cease grazing as they would if they were hand-fed.
- An increase in grazing distribution. Cattle can
be drawn into less heavily grazed areas through free-choice blocks and
- A decrease in labor and delivery costs.
Visit with your Purina Mills representative, who can help you determine
which IM Technology product best fits your production system and goals.
*“Forage Quality Photo Guide,” Texas AgriLife Extension Service Publication