Sodium (Na)
Sodium is an alkali metal. It plays an important role in moisture management for both animals and plants. Below, a distinction is made between the role of sodium in animal husbandry and sodium in soil and crops.
Sodium in animals
Sodium (Na), together with chlorine (Cl) and potassium (K), plays an essential role in the osmotic pressure of body cells and thus the moisture balance of the body. Together, these minerals determine the cation-anion difference (also called acid-base balance) of the ration and likewise of the body.
Sodium plays a role in the transmission of nerve impulses and in the production of enzymes essential for the absorption of glucose and certain amino acids. Sodium also has a buffering function in the gastrointestinal tract in the form of sodium carbonate and sodium phosphate. Normally, sodium levels in the blood are kept very constant. To get more clarity on sodium supply, saliva can be examined.
| Category | g/kg dry matter | g/animal/day |
|---|---|---|
| Young cattle from 4 months | 0.6 | 2.3 |
| Young cattle from 9 months | 0.5 | 3.0 |
| Young cattle from 16 months | 0.5 | 4.0 |
| Dry 8-3 weeks to calving | 0.7 | 7.6 |
| Dry 3-0 weeks to calving | 0.6 | 6.6 |
| Lactating (20 kg) | 1.1 | 20 |
| Lactating (40 kg) | 1.4 | 33 |
Sodium deficiency
Sodium deficiency does not cause specific deficiency symptoms, but usually leads to decreased feed intake, fertility and production. Other symptoms that may be observed are emaciation, drowsiness, dry, stiff skin, urine drinking, licking and afterbirth that doesn’t come off.
Sodium excess
Sodium excess may occur alongside excessive salt intake, water deficiency and diarrhea (excessive fluid loss). Symptoms of sodium excess include excessive drinking, a stiff gait and muscle tremors. The CVB (2005) indicates a toxicity limit of 10 g/kg dry matter (for chronically high levels).
Sodium in soil and crop
Sodium plays a role in the moisture balance of plants. A higher sodium content has no effect on grass yield, but it does affect the palatability, and therefore dry matter absorption, of grass and grass silage. Normally, grass and grass silage contain an ample amount of sodium. In contrast, silage maize, CCM, beer brush, pressed beet pulp and cereals are low in sodium.
| Fresh grass | Grass silage | Maize silage | Lucerne | |
| Average | 2.1 | 2.4 | 0.2 | 0.9 |
| Target range | - | 2.0-3.0 | 0.1-0.3 | - |
Sodium is prone to leaching in soil; especially on sandy and valley soils, sodium content is often on the low side. There is competition between sodium and potassium for the uptake of minerals by crops. The analysis Fertilization Manager from Eurofins Agro takes this into account: when, for example, the potassium content is higher, more sodium (salt) is advised for the same sodium content. In this way, the required amount of sodium can still be absorbed by the crop. The Fertilization Guide provides advice for all soil types.