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Beef Cattle Nutrition and Feeding
Frequently Asked Questions
Protein Supplements and Hay Intake
In recent years, providing low intake (less than 3 lbs per day), nutrient
dense supplements such as cooked molasses tubs and range meals have become
popular in Arkansas for winter supplementation of cattle consuming hay. Protein
supplementation has been shown to improve intake and digestibility of forages.
However, before you conclude that protein supplementation will take care of your
herd, take the time to investigate how much protein is in the hay being fed by
forage testing.
Companies that advertise the benefits of protein on intake and digestibility
are usually presenting data for herds consuming low quality (prairie grass) hays
that are less than 8% protein. It is common for some hays to test as low as 4%
protein. Mature prairie grass hays are notorious for being low in protein.
Inadequate amounts of protein, degradable in the rumen, results in a reduction
in the microbial population. Since the ruminant relies on these microbes to
digest forages, a reduction in microbial population will likewise result in a
depression in fiber digestion. If the rate of digestion is reduced, nutrients
will leave the rumen more slowly. If you think of the rumen as a tank with two
pipes (an inlet and outlet), once the tank reaches its maximum volume, and the
amount of flow exiting the outlet pipe is reduced, the amount of flow coming
into the tank will decrease as well. Therefore, forage intake, digestibility and
animal performance are reduced all because of low dietary protein.
In a review by two ruminant nutritionists, McCollum and Horn (1989 American
Society of Animal Science meeting symposium paper), the authors noted that
intake response to protein supplementation was not enhanced once the amount of
protein in the forage was greater than 10% and total dietary protein (forage
plus supplement) was greater than 14%. A database of more than 7,000 hay samples
submitted to the University of Arkansas Agricultural Services Lab indicated that
41% of hays were below 10% protein. In addition, an optimal balance between
protein and energy is important, and a ratio less than 7:1 (TDN:CP) has been
suggested by researchers. The majority of samples (93%) in the database had a
ratio less than 7:1.
The only way to truly determine if protein supplementation is warranted is to
forage test. Producers that practice good fertility management, fertilizing
according to soil test recommendations, and harvest forages for hay before they
become mature will likely produce hay that is sufficient in protein. Under these
management conditions in Arkansas, protein supplementation will likely not
enhance forage intake as observed with low quality prairie hays out west.
Additional improvements in animal performance may be observed which may be in
part due to the fact that most natural protein sources will be higher in energy
content than hay and energy may be the limiting factor. In this case, supplying
a low protein, high energy supplement will be more economical.
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Nutrition and Feeding Frequently Asked Questions
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