Using Salt to Limit Intake
Cattlemen continue to investigate ways to reduce cow costs. One management tool frequently used is regulating feed intake with salt. Research would suggest that regulating feed intake with salt is not precise meaning that the salt content may need to be adjusted throughout the feeding period to achieve the desired feed intake. As a management practice, self-feeding supplements tend to allow timid, slow-eating cows to get their share and it is an easy method of providing Vitamin A, phosphorus and other feed additives.
Salt should always be supplemented to beef cows. Salt is made up of Sodium and Chloride (NaCl) and these elements are used in a number of important reactions in the body. Daily salt requirement for mature cattle is less than 1 oz/head/day. Voluntary salt intake often exceeds minimum needs. Because there are practical limits to the amount of salt cattle eat, salt can be used to restrict the consumption of highly palatable feeds. In such instances daily voluntary intake of salt will approximate 0.1 pound salt/100 pounds body weight for most classes of cattle.
Total salt intake is the amount in the feeds that are eaten and the amount in the water that is drank. Salt toxicity is seldom seen in cattle because of their high tolerance for salt. As a rule-of-thumb, cattle on salt mixtures drink 50 or 75 percent more water than normal or approximately 5 gallons of additional water for each pound of salt. If only salty water is available, cattle will often refuse the supplement or may be forced into a toxicity situation. Salt content of water is usually measured by total dissolved solids (TDS) which includes calcium, magnesium, sodium chlorides, sulfates and bicarbonates. Caution is necessary in using salt-limited supplements when water contains above 5,000 ppm TDS. This analysis can usually be obtained through the analytical laboratories.
When cattle are accustomed to eating supplements but are unaccustomed to self-feeding, overeating can be prevented by starting with a high salt level (50:50 or even 60:40 salt to meal) and then reducing salt level to obtain desired level of intake. If cattle have not eaten concentrates before, a training period of a week or more of daily hand feeding of meal without added salt may be necessary, particularly with young cattle. Usually is necessary to increase the salt content of the mix over a period of time as cattle become accustomed to the high salt level. Self feeders should protect the feed/salt mixtures from wind and rain and be portable.
When using salt to limit intake of feeds or supplements consider the following:
- The proportion of salt to limit intake in self-fed mixtures will vary from 5 to 60 percent.
- The amount of salt needed will be determined by the desired feed or supplement intake.
- Use plain white salt. Coarsely ground salt is better than finely ground salt.
- Logically, to increase supplement intake, decrease salt in the supplement. To decrease supplement intake, increase salt in the supplement.
- As weight of the animal increases, the amount of salt needed to limit intake of the supplement to the desired level will need to increase.
- Age seems to impact salt intake. If cattle weigh the same, less salt will be needed to limit supplement intake to the desired level in the younger compared to the older animal.
- As animal become more accustomed to the salt in the supplement, more will need to be added to limit the intake to the desired intake level.
- To assure that calves do not over-eat, set the levels high the first two to three days and consider hand-feeding the feed or supplement.
- To prevent separation of feeds in the supplement, particle size needs to be similar. That's the reason for the recommendation to use coarsely ground salt.
- If grains are included, it should be cracked or coarsely ground.
- Including an ionophore,in the feed or supplement that is being limited using salt will reduce the amount of salt needed to limit the intake to the desired level. Follow lable directions on use and amounts to be consumed.
- If the water that is available for the cattle to drink when salt is used as a feed limiter is above 5,000 ppm Total Dissolved Solids (TDS) caution is necessary
- Feeders should be portable and feed protected from wind and rain.
- Strategic placement of feeder can impact grazing distribution.
- Do not place feeders next to the water source in a pasture as it will effect grazing distribution.
- To monitor supplement consumption, know the initial amount of supplement in a feeder. Every day for the first three to four days, check the feeder to get a rough estimate of the amount of feed being consumed.
If salt is used in the winter to limit feed intake, make sure the water source is not frozen.
Dr. Rick Rasby, Professor of Animal Science
Animal Science, University of Nebraska–Lincoln, Lincoln, NE