As with many myths or “home remedies” there are many people that will go to lengths to defend it. All one need to do is consult any of the internet chat groups to see this. Talking to people at the local sale barn to hear armchair veterinarian advice on the so-called advantages of feeding sulfur salt to livestock.
Sulfur’s role in parasite control
Might as well start with the main topic that always is brought up when talking about sulfur blocks. Let us go over the role of sulfur in controlling pests.
Historically sulfur has been used as a treatment for external parasites. Sulfur-containing compounds are used extensively by horticulturists to control external parasites. Animal use comes in the form of a lime-sulfur solution that is applied externally to the animal. Topical use of sulfur is moderately successful in external parasite control.
The other side to this is that there is no evidence that supports the belief that adding sulfur to the diet will control external parasites such as flies, fleas, ticks, etc. Since there is not any evidence, as far as I have been able to find, the use of sulfur in this way would fall into the category of “old wives tales”. It has not been proven to control parasites and too much of it can also be detrimental to your livestock.
Sulfur is necessary though
Sulfur is a necessary mineral that is need in order to maintain life. It is found in every cell of the body and helps to regulate body functions. In fact concentrations of it are particularly high in hair, skin, and hooves.
Many key compounds within the body including amino acids (methionine, cystine, cysteine, and taurine) contain sulfur. B vitamins (thiamine and biotin) as well. Compounds containing this element are responsible for structural integrity (collagen), chemical reactions (enzymes), oxygen transport (hemoglobin), energy regulation (insulin), and milk let down (oxytocin) as well as many others.
Despite the fact that it is a key mineral necessary for life, adding inorganic sulfur to the diet is not necessarily for the health of most animals. Most animals get adequate amounts of sulfur through organic sources. These include sulfur-containing amino acids, biotin, thiamine, and others in their diet.
Now you may be thinking that with the importance that sulfur plays in a living organism that must mean that you will need to supplement with a block. That is not always true though. Sulfur does not need to be supplemented compared to other minerals.
How they can get it
Under normal circumstances the animal can get all the sulfur their body requires just from their normal diet. They can get it from the forages they consume. Depending on where you are located they can even get it from the water that they drink. Because they can get it naturally it can be very easy to overprovide it.
Plants and microbes are capable of synthesizing sulfur-amino acids from inorganic sources. This means that many feedstuffs including molasses, cottonseed meal, soybean meal, etc. are already rich in it. In fact research has shown that excess amounts in the diet results in reduced animal performance.
When a diet high in non-protein nitrogen is fed is the only exception to when inorganic sulfur is necessary. In this instance the rumen microorganisms need inorganic sulfur in order to manufacture sulfur containing amino acids from the non-nitrogen protein. In this case a common recommendation is to feed a nitrogen to sulfur ration of 10:1.
The negative effects of too much Sulfur
Sulfur toxicity
The margin between desirable and harmful concentrations of sulfur in a ruminant diet is very small. How small you may ask, well according to a paper from the University of Georgia the sulfur requirement is only 0.15% of intake. It also goes on to say that the maximum tolerable level is 0.40%.
When excessive amounts of it are present, greater than the ability of the rumen microbes to utilize it, the excess is absorbed into the blood stream as Sulphides. Sulphides are toxic and often result in reduced appetite and growth rate. Necrosis of brain tissue can also occur in these cases. In addition, some sulfur-compounds can destroy thiamine activity.
Many believe the development of PEM (polio encephalomalacia) is more closely tied with excess sulfur rather than thiamine deficiency. Classic symptoms of PEM include animals that often press their head against a wall or post. They can also become “star gazers” which is where they will stand with their head back over their shoulders looking up at the sky. If not treated with thiamine most affected animals will die within 48 hours.
Mineral interactions
It directly interacts with other essential minerals including copper, selenium, and molybdenum. Chronic exposure to high levels in the diet will have an adverse effect on ruminants, mostly by including copper deficiency. One sign of a copper deficiency is rough hair coat.
Excess amounts in the rumen reduces the bioavailability of copper by the formation of insoluble copper sulfides. The animal will not be able to utilize these sulfides. The copper will be requirement is increased when the excess makes it unavailable. High levels of molybdenum in the diet will make the copper deficiency worse.
A variety of key body systems need copper. A lot of key enzymes needed for reproduction, immunity, and growth require copper. Also, copper is necessary for the metabolism of iron, maintenance of connective tissue, pigmentation of skin and hair, maturation of hoof tissue, and many other functions.
Animals that are mildly to severely deficient in copper will display one or more of the following symptoms: loss of pigment around the eyes, winter coats that are slow to shed out, decreased conception rates, increased days open, hoof problems, and/or depressed immunity.
If you are still not sure what salt block you should go with then check out my previous post “Which color salt block is best?”.