With most of southern Oklahoma and northern Texas experiencing the worst drought in almost 20 years, hay is scarce and very expensive. Thus, many producers are looking for alternative feed sources. Fortunately for cattle producers, grain prices are low this year due to an expected bumper crop of corn coupled with decreased grain exports caused by recent economic turmoil in Asia. As a result, corn is price competitive with hay as a source of nutrients for the cow herd. Because corn is "energy dense" (high in calories) it must be fed at a restricted level. Limit feeding high energy diets to cows requires careful thought and planning. However, if done properly, it is possible to maintain cows on a diet composed largely of corn with only a relatively small amount of hay (three to seven pounds per head per day) and one to two pounds of protein supplement.
Understand the Nutrient Requirements of Cows Nutrient requirements of your cows depend upon their weight, milk production potential and lactation status (lactating or dry). Table 1 shows approximate daily feeding levels of corn, protein supplement and hay for dry and lactating cows of varying mature weights and milk production potentials. Hay consumption in this example is 7.5 pounds per day. In practice, hay can be restricted to as little as 0.25% of body weight (2.5 pounds for a 1,000-pound cow). However, as hay levels decline, other dietary components must be adjusted. Furthermore, with very low hay intake there is increased risk of digestive and metabolic disorders.
Management Considerations Before initiating a corn-based feeding program carefully consider management requirements. Some major concerns are listed below.
Grain Storage: In order to effectively use whole corn (or other grains), you need bulk storage capability. Storage systems must allow ease of handling and minimal wastage.
Bunk Space: Adequate bunk space is essential to a limited feeding program. Every cow must be able to eat the appropriate amount of feed daily. Make 2.5 to 3 linear feet of bunk space available per cow. If cows have horns, additional bunk space may be needed. Watch cows to make certain that every cow has access to feed. Isolate and feed timid cows separately. Restrict access to feed bunks until feed has been placed in the bunk. Otherwise aggressive cows may consume much larger quantities of feed than less dominant cows.
Site Selection: Limit fed cows will be somewhat hungry (especially during the first few weeks of feeding). Fences must be adequate to keep cows in the feeding area. The site will be heavily impacted during the limit feeding program. Make sure that the site is well drained. Avoid using areas containing standing forage that you want to preserve. The feeding site will be denuded.
Grain Processing: There is little advantage (if any) derived from processing grain for cows. Whole corn will be consumed and digested more slowly than processed grain. This reduces the risk of acidosis and other metabolic disorders.
Protein Supplementation: In the example in Table 1, cottonseed meal served as a protein supplement. Soybean meal could be used alternatively. Because supplement will be fed at low levels, it can be purchased in a sacked form and "top dressed" over the corn. If supplement is pelleted, ionophores (monensin, lasolocid, etc.) may be added. Inophores will improve the efficiency of feed utilization and reduce feeding costs and incidence of bloat and acidosis. Some feed manufacturers are marketing supplements specifically designed to be fed with whole corn.
Hay Feeding: A limited amount of hay must be fed daily. The amount fed is small so it must be distributed to provide equal access for all cows. Square bales are more easily used in a limit feeding setting than round bales. If round bales must be used, place in rings and limit access time. It will take some practice to estimate the time required for cows to eat the desired amount of hay. But keep in mind, there is some room for error (cows may eat as little as 2.5 to 3 pounds of hay per day). If you "time limit," be certain that all cows can eat (use an adequate number of bales).
Change Diet Slowly: Begin feeding corn gradually. Increase incrementally over a two-week period.
Monitor Cow Condition or Weight: Cows will lose fill as you begin limit feeding. Do not be alarmed, this is expected! After cows lose fill, monitor condition carefully. Photographs can be useful tools when monitoring body condition. Take pictures of a few easily identified cows. Periodically compare current body condition of these cows to photographs to determine if they are losing or gaining body condition. If cows seem to be losing weight, increase the amount of corn fed daily. If you have a scale, it may be useful to identify "indicator cows" to weigh periodically.
Mineral Supplementation: With a corn-based diet, phosphorus is abundant and calcium may be lacking. This may become particularly critical at calving time. To avoid problems 1) add 0.2 to 0.25 pounds of limestone per head per day to the ration or, 2) make a high calcium mineral supplement available on a free-choice basis. If an ionophore has been added to the protein supplement, avoid a mineral supplement containing a similar product. Toxicity will occur if cattle are overfed ionophores.
Test Locally Grown Corn for Aflatoxin: Due to drought related stress, corn from this region may have elevated levels of aflatoxin. Testing is advised. Corn produced in northern regions (Corn Belt, Kansas, etc.) should be safe. The Noble Research Institute has a fact sheet that discusses levels and testing procedures.
Cost Effectiveness of Limit Feeding. The viability of a limit feeding program is entirely dependent upon the relative price (or cost of production) of hay compared to the price of corn. Compare corn to hay on the basis of the price per unit of energy. This is most easily done by expressing the energy value as percent total digestible nutrients (TDN). We can then calculate the price per ton of TDN in hays that vary in TDN and price. With this information we can derive the equivalent price of corn. Table 2 displays the relative value of corn when compared to low, medium and high quality hay at $50, $70 and $90 per ton. Notice that the price you can pay for corn is dependent upon 1) percent TDN of the hay and 2) the price of hay. For example, if average quality hay is available at $70 per ton, you could pay up to $116.23 per ton for whole corn. However, if high quality hay is available for $50 per ton, the equivalent value of corn is only $75.86 per ton.
Limit feeding of energy-dense feeds is no doubt a viable option this year given the high price and poor availability of hay. This practice may also be practical and cost effective for skilled producers as a standard management practice (as long as corn is inexpensive). Keep in mind, this is a management intensive practice. This system will not work if management skills are lacking.