Definition

Sulphur (S) is an essential mineral for both plants and animals. It is a key component of sulphur-containing amino acids such as methionine and cysteine, which are vital for protein synthesis. In ruminants, sulphur plays a crucial role in the production of microbial protein within the rumen. 

Importance

Sulphur is not only important for protein formation but also forms part of:

• B vitamins such as thiamine and biotin
• The hormone insulin

Adequate sulphur intake supports rumen microbial activity, feed efficiency, and overall animal health.

Sulphur requirements (CVB, 2016)

Sulphur deficiency

A deficiency in sulphur can lead to:

• Reduced feed intake and milk production (due to impaired rumen microbial activity)
• Dull hair coat
• Excessive salivation
• Moist eyes

Sulphur excess

Sulphur toxicity can occur relatively easily:

• Symptoms may appear at 3–4 g/kg dry matter
• CVB (2005) sets a chronic toxicity limit at 4 g/kg dry matter

Effects of excess sulphur

• Acute excess (sulphite form): Nervous system disorders, intestinal inflammation, blindness, muscle twitching, diarrhoea, dehydration, lung and kidney damage, bleeding
• Sulphate form: Less severe; mainly causes osmotic diarrhoea
• Chronic excess: May lead to copper deficiency

Key considerations

• Monitor sulphur levels in the ration to avoid both deficiency and toxicity.
• Balance sulphur intake with other minerals, especially copper.
• Consider feed composition and fertilisation practices that influence sulphur content.

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