Role of Sulphur in Livestock Nutrition

Pashu Sandesh, 05 August 2023  

Bharti Yadav¹, Praveen Kumar Agrawal² Monika Karnani³, Sheela Choudhary⁴, and Manju⁵

Department of Animal Nutrition

Post Graduate Institute of Veterinary Education and Research (PGIVER), Jaipur

¹ PG Scholar, Department Of Animal Nutrition, PGIVER, Jaipur

²PG Scholar, Department Of Animal Nutrition, PGIVER, Jaipur

³ Assistant Professor, Department Of Animal Nutrition, PGIVER, Jaipur

⁴ Professor& Head, Department Of Animal Nutrition, PGIVER, Jaipur

⁵Assistant Professor, Department Of Animal Nutrition, PGIVER, Jaipur

Introduction:

Sulphur being one of the seven (7) major minerals is believed to be essential for the forms of animal life as Sulphur containing compounds that have metabolic, structural & regulatory functions are ubiquitous.

Sources of Sulphur 

Sulphur concentrations in pasture and conserved forages range widely from 0.5 to >5.0g, kg−1DM, depending on plant species, availability of soil S, N and P, sward maturity and climate.

Usually, cereal grains tend to be low in sulphur (approx. 1g/kg ) but cereal straws and forage grown on biosolids are slightly richer (1.4-4g/kg ) protein supplements rich (2.2-4.9 g/kg ) in sulphur. In plant-based feed, brassica crops such as kale & turnip leaves are rich sources of sulphur.

Bioavailability of sulphur

Inorganic & elemental sulphur is not usually absorbed in the body so not available to animals while the apparent availability of sulphur from plant sources is 50-70%. 

METHIONINE > Ca SULPHATE >NH₄ SULPHATE> Na SULPHATE>Na SULPHIDE > MOLASSESS> Na SULPHIDE>LIGNIN SULPHONATE>ELEMENTS

Nutritive value of sulphur in feeds 

The value of feeds as sources of sulphur for ruminants depends entirely on their availability for MPS. This in turn depends on the co-availability of other factors needed for MPS and therefore presents unique problems. Nutritive value is regarded by some to be more closely related to ratios of sulphur to nitrogen than to sulphur concentration in feeds.

Functions of Sulphur

The functions of sulphur are as perse as the proteins of which it is a part. Sulphur is frequently present as highly reactive sulfhydryl (SH) groups or disulphide bonds, maintaining the spatial configuration of elaborate polypeptide chains and providing the site of attachment for prosthetic groups and the binding to substrates that are essential to the activity of many enzymes. Hormones such as insulin and oxytocin contain sulphur, as do the vitamins thiamine and biotin. The conversion between homocysteine and methionine facilitates many reactions involving methylation. Cysteine-rich molecules such as metallothionein play a vital role in protecting animals from excesses of copper, cadmium and zinc, while others influence selenium transport and protect tissue from selenium toxicity. Glutathione may facilitate the uptake of copper by the liver. Glutathione also protects tissues from oxidants by interconverting between the reduced (GSH) and oxidized (GSSG) state, and may thus protect erythrocytes from lead toxicity. Sulphur is present as sulphate (SO₄) in the chondroitin SO₄ of connective tissue, in the natural anticoagulant heparin and is particularly abundant in the keratin-rich appendages (hoof, horn, hair, feathers, wool fibre and mohair). However, the primary rate-limiting function in sulphur-deprived ruminants is related not to the functions or associations listed above, but to rumen fermentation and microbial protein synthesis (MPS) (Durand and Komisarczuk, 1988). 

Metabolism of sulphur 

Metabolism varies based on the digestion process in monogastric & ruminants. 

 In monogastric elemental & inorganic sulphur is not useful and feed sulphur is converted in organic form in amino acid (cysteine, methionine) and is actively absorbed from the upper small intestine.

   In ruminants, inorganic sulphur is converted into organic form by ruminal micro-flora while organic sulphur enters in sulphide pathway &absorbed from the ruminal wall & small intestine by active transport.

Fig: Primary flows of sulphur in the liquid compartment of the rumen: metabolizable energy and nitrogen supplies, as well as sulphur and phosphorus, determine the most important product, microbial protein, entering the duodenum (amounts of S, g day−1 are from the ‘low’ S treatment of Kandylis and Bray, 1987): the rumen also has a gas compartment into which sulphide diffuses as H₂S. Approximately 50% leaves as sulphide by absorption, eructation and exhalation, when SO₄ is the major dietary source.

Interrelation with other elements & mineral 

Being a reactive element sulphur has a certain interactive relationship with other minerals & affects their availability & absorption in the body.

1. Cu-S-Mo Interrelation

In presence of sulphur high Mo causes Cu deficiency due to the formation of insoluble Cu-Mo-S complex (thiomolybdate) in the GI tract. It reduces cu absorption (formation of Cu- sulphide in the rumen), decreases Cu availability. Thiomolybdate affects S metabolism (sulphide formed).

2. S-Se Interrelation

Due to similar chemical structures, act as competitors of each other. Se AA~ SAA compete for the reactive sites on enzymes. High S levels in diet depresses glutathione peroxidase activity (SE-containing enzyme).

Deficiency of sulphur

Closely related to protein deficiency, sulphur deficiency can have similar detrimental effects on livestock that can negatively impact production and income potential among farmers by:

• Reducing the rate of microbial synthesis, leading to reduced microbial protein and volatile fatty acid production
• Reducing fibre digestion as a result of slower microbial growth in ruminants
• Slowed growth rates
• Reduced feed efficiency
• Reduced milk production
• Reduced feed intake                                                                                                                                                     
• If sulphur deficiency increases in severity without rectification, visible symptoms will become increasingly evident among livestock, such as
• An increased unwillingness to eat
• Excess weight loss
• Stunted growth, dullness and lethargy
• Excessive salivation
• Death

Doses & Supplementation 

• For monogastric animals – S is needed for the methionine synthesis requirement. 
• A diet low in sulphur (less than 0.1% in DM) can be supplemented with 3gm of inorganic S/100g (1 part S to 15 part of NPN) in ruminants.
• In ruminants – Ca Sulphate can also be given to growing cattle,
• Molasses-urea-bran block: these blocks include sulphate of ammonia along with molasses, and urea.
• By method - S fertilization of forage crops, S can also be incorporated in green fodder and forages.  

Sulphur Toxicity

Polioencephalomalacia (PEM) was first reported in 1956 and was described as a neurologic disorder of cattle characterized by blindness, ataxia, recumbency and seizures.  The micro pathological description was laminar cortical necrosis.  This description of PEM is still accurate 50 years later, but several additional causes have been identified.

Polioencephalomalacia in cattle was thought at one time to be caused exclusively by a thiamine deficiency.  The deficiency was thought to develop because the rumen did not produce enough thiamine or products such as amprolium inhibited thiamine production. Some of the confusion surrounding the cause of PEM is because there is no method to accurately evaluate thiamine status in animals.  It is now known that the laminar cortical necrosis observed in the brain can be caused by sulphur toxicity in addition to lead toxicity, salt toxicity, hypoxia, thiamine deficiency and vascular damage in general.  Sulphur toxicity is still responsive to thiamine treatment but is not caused by a thiamine deficiency.  At one time, blind staggers or PEM observed in Wyoming were thought to be caused by selenium toxicity.  This theory has now been discounted and the condition is known to be caused by sulphur toxicity.

When sulphur is ingested in excess, rumen microbes produce too much hydrogen sulphide.  The soluble hydrosulphide anions stay in the rumen fluid phase and hydrogen sulphide gas accumulates in the rumen gas cap.  The hydrogen sulphide is absorbed across the rumen wall into the bloodstream.  This elevated level of sulphide in the blood interferes with cellular energy production. Since the brain has a high requirement for energy production it is one of the most affected body systems.  Sulphide interferes with energy production much in the same way that cyanide does.  It is thought that sulphur and cyanide interfere with cytochrome oxidases, the terminal enzymes of respiratory chains in mitochondria.

Sulphur intake can occur in the feed or water so the total dietary intake of sulphur is needed to evaluate the risk of developing PEM.  This is especially pertinent in Iowa now because of ethanol by-products, especially dried distillers grain with solubles (DDGS).  Ethanol by-products may contain a high concentration of sulphur.  When cattle are transitioning to high sulphate intake conditions, the ruminal sulphide concentration peaks 1 to 3 weeks after the change

Conclusion

Sulphur is a major mineral needed in the body for the synthesis of various protein, vitamins, and hormone synthesis and its deficiency is detrimental to animals in reduced production and efficiency while its toxicity in cattle (PEM) is also a setback to cattle health.

Reference:

Bird, P.R. (1972a) Sulphur metabolism and excretion studies in ruminants. V. Ruminal desulfuration of methionine and cysteine. Australian Journal of Biological Sciences 25, 185–193.

Dewhurst, R.J., Kim, E.J., Evans, R.T., Cabrita, A.R.J. and Fonseca, A.J.M. (2007) Effects of dietary sulphur sources on concentrations of hydrogen sulphide in the rumen head-space gas of dairy cows. Animal 1, 531–535.

Drewnoski, M.E., Ensley, S.M., Beitz, D.C., Schoonmaker, J.P., Loy, D.D. et al. (2012) Assessment of ruminal hydrogen sulphide or urine thiosulfate as diagnostic tools for sulphur induced Polioencephalomalacia in cattle. Journal of Veterinary Diagnostic Investigation 24, 702–709. 

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Kandylis, K. (1984b) Toxicity of sulphur in ruminants: a review. Journal of Dairy Science 67, 2179–2187. 

Kandylis, K. and Bray, A.C. (1987) Effects of variation in dietary sulphur on the movement of sulphur in the rumen. Journal of Dairy Science 70, 40–49.

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Spears, J.W., Burns, J.C. and Hatch, P.A. (1985) Sulphur fertilisation of cool season grasses and effect on utilisation of minerals, nitrogen and fibre by steers. Journal of Dairy Science 68, 347–355.