Question: How should salt licks be used? Can they be used to combat osteoarthritis in cattle?

The main causes of osteoarthritis (inflamed joints) in cattle are a deficiency in protein, phosphorus, magnesium and manganese. It can be caused by feeding the incorrect licks, as well as by the high intake of calcium from the soil, drinking water, pastures and licks.

If only rock salt or salt licks are fed, the animal ingests too much salt. This disturbs the osmotic balance in the body’s fluids as well as the absorption of phosphorus, and leads to a phosphorus deficiency which, among other possibilities, also manifests as osteoarthritis.

Feeding bone meal as a source of phosphate is not recommended because the phosphate here is in the form of tricalcium phosphate, which is only about 50% bioavailable. As soon as the nitrogen content in the dung of an animal is less than 1.3% (and therefore about 8% protein), animals are not able to use the phosphate content efficiently and a phosphorus deficiency results.

On many farms, especially those that have a lot of grass, the protein content sinks below the critical level of 8%.
Protein then also has to be supplemented. When there is a protein deficiency, intake (Siebert et al., 1975) as well as retention of phosphorus (Roy et al., 1970) in the animal’s body are compromised.

According to Sykes & Field (1972), a protein deficiency will inhibit the formation of the bone matrix, and therefore also bone growth. When supplementary bone meal licks are given, not enough trace elements are supplied.

In addition, the high calcium intake also suppresses the absorption of trace elements, because of calcium’s antagonistic effect.

To manage osteoarthritis, biologically available trace elements need to be supplemented. In addition, these animals have to be injected at least twice with Multimin and also vitamins A and E 4 weeks before mating and 4 weeks before calving.

TESTING AND TREATING

• Have liver analyses performed on cattle to determine their trace element status.
• In some areas, it is also essential to administer a copper supplement.
• If there is a protein deficiency in the animals’ grazing, they will ingest a large quantity of bone meal lick in an attempt to satisfy their need for protein.
• Because bone meal contains protein, the response noted on feeding bone meal licks is often the result of protein, rather than the phosphorus, content.
• Salt licks, such as rock salt, should not be fed at the same time as phosphate mineral licks.
• In fact, they should not be given with any other licks because animals prefer salt and, therefore, ingest very little, or none, of the mineral lick (Arthington, 2002)
• “Ruminants have an appetite for sodium and if sodium is provided free-choice, they will consume more than the require (Buskirk et al., 2002).
• “Despite the inability to ensure that every animal receives the desired amount, lick supplementation is still the most appropriate form of supplementation of minerals” (McDowell, 1996).
• It is preferable that licks be placed at the opposite end of the camp to the water source.
• This will, at the same time, encourage the cattle to graze away from the water source and possibly limit trampling around watering holes.

Also read:
Livestock production: Trace elements for ruminants
Livestock production: How to supplement trace elements correctly
Livestock production: Dealing with trace element antagonists

• This article was written by Dr. Jasper Coetzee and appears in Ask the vet: What cattle farmers should know (1), compiled by Dr. Faffa Malan.