Editor’s note: This column originally referred to a set of tables that could not be reproduced in print. Accordingly, the references to these tables have been removed.
The goal of a profit motivated beef cow-calf enterprises is to convert forage resources into pounds of beef. The basic premise behind forage based beef production is that cows can harvest their diet more efficiently and cheaply than beef producers can harvest or buy, store, and feed to them. However there are times even in the best planned and managed forage systems that supplemental feed is needed due to a lower than needed level of nutrients in the basal forage or simply a lack of available grazed or harvested forage.
To determine whether supplemental feed is needed you must know the nutrient requirement of the animal being fed and the nutrient profile of the forage offered. Listed in the table are the dry matter intakes plus the dry matter nutrient percentages required by a 1300# mature beef cow of average milking ability during her various stages of production.
If there is plenty of forage which meets or exceed the nutrient levels listed above then no supplemental feed is needed. To determine the nutrient content of forage you can submit a forage test to your local extension office. Many offices will have a forage probe which can be used to sample hays or silages. As you can see by far the highest amount of nutrients are needed by the cow during the first 90 days of lactation. Matching up that period of production with the time when you have the most available nutrients in the pasture is a key to reducing feed costs.
Forage which is less than seven percent crude protein creates problems on several fronts. In addition to not meeting the biological needs of the cow, forage of that protein level or lower does not provide enough nitrogen in the diet to support a rumen microbe population that can digest forage efficiently. This results in a reduced intake of a lower quality forage which compounds nutrient deficiencies.
That is why protein is most often the first limiting nutrient of grazing dormant grass or cows fed low quality hay. Providing supplemental protein to cows consuming low-quality forages that contain less than 7% crude protein in fact supplements the cow both directly and indirectly by supplementing the rumen microbes resulting in an increase in forage intake and utilization.
When protein is needed supplying it in a more concentrated form results in an increase in forage intake.
Based on this information the protein supplements should contain more than 30% crude protein on a dry basis to maximize forage intake and the resulting increase in protein and energy supplied by the forage. In some situations energy may limit performance even after the cow’s protein requirement has been met. This most often occurs when feeding first calf heifers or 3 year old cows during lactation. Feeds that contain high levels as starch perform more like substitutes than supplements to the fact that they have a negative effect on forage intake and utilization, which subsequently decreases overall energy intake.
Page 2 of 2 - Potential supplements should always be evaluated on a cost per unit basis of the most limiting nutrient ($/lb crude protein or $/ lb of energy). Storage and delivery method are also important considerations. It is often economically advantageous to purchase supplemental feeds during late summer or fall for use during the winter months.
However, cattle producers must weigh the feasibility and costs associated with storing feedstuffs to the expected cost of the feeds at a later time before making a purchasing decision. If storage facilities are inadequate or unavailable, delaying purchasing may be more economical than investing in storage facilities.
However, cattle producers should not overlook simple methods of storage such as covered commodity bays, or making temporary storage bays in buildings with concrete floors.
An excellent publication on beef cow nutrition is available online at: http://www.ksre.ksu.edu/library/lvstk2/c735.pdf For information about this and other livestock topics contact the K – State Research & Extension, Wildcat District office at (620) 784-5337 or email me at firstname.lastname@example.org.