To supply sodium in poultry diets, sodium sulphate is a cost-effective alternative to sodium bicarbonate with positive effects on the Dietary Electrolyte Balance (DEB) and additional benefits on feed and litter quality. Adisseo offers AdiSodiumTM, a pure source of sodium sulphate.
The positive effect of sodium bicarbonate, in DEB studies, has always been due to the supply of sodium and not to the supply of the bicarbonate ion. Dietary bicarbonates should not be confounded with blood bicarbonates, which have to be regulated to ensure physiological functions. Dietary bicarbonates convert straight away to H2O and CO2 in the acidic environment of the gizzard (Hunt, 1970). This CO2 is then quickly eructed and will not have any impact on blood pH. Besides, the DEB calculation only takes into account Na, K and Cl and not HCO3-.
In this context, sodium sulphate can be an alternative source of sodium without chloride. Adisseo produces and sells AdiSodiumTM, a pure source of sodium sulphate. It has been tested in numerous trials (broilers, turkeys or layers) and is now widely used in poultry and pig diets, particularly in France. For example, in a broiler trial by Mercier et al. (2005) similar performance of broilers was obtained with diets containing sodium bicarbonate or AdiSodiumTM (see graph below)
No differences between AdiSodiumTM and sodium bicarbonate on broiler performances (Mercier et al. 2005)
* NaCl also added to the diets to fulfil chloride requirement (0.32% from 0 to 14 days, 0.27% from 14 to 28 days, 0.24% from 28 to 42 days
Another trial has been carried out by De Los Mozos and Mercier (2007) on heat stressed broilers to challenge the belief that dietary bicarbonate ions play a role in hot conditions. The results are shown in the table below. No differences were observed between the sodium bicarbonate and AdiSodiumTM treatments.
No differences between AdiSodiumTM and sodium bicarbonate on broiler performances in temperate and hot conditions (De Los Mozos and Mercier, 2007)
* NaCl also added to the diets to fulfil chloride requirement (0.25% from 0 to 13 days, 0.30% from 13 to 43 days)
Sodium sulphate has another benefit over sodium bicarbonate in that it has a much lower Acid Binding Capacity. The Acid Binding Capacity of sodium sulphate is 96 mEq H+/kg whereas that of sodium bicarbonate is 11 066 mEq H+/kg (Lawlor et al. 2005). This means that, compared to sodium bicarbonate, sodium sulphate can improve digestion in the upper digestive tract of poultry and also improves the efficacy of organic acids, if used.
Scientific literature generally shows that increasing the DEB level in broilers induces an elevation of litter pH. This makes sense as the higher is the DEB, the less acidic is the blood and the more important is the excretion of HCO3-. Higher litter pH induces higher ammonia emissions from the litter. In the trial by Mercier et al. (2005) replacing sodium bicarbonate by AdiSodiumTM to increase the DEB of broiler diets, resulted in a lower litter pH and lower ammonia emissions from the litter (see Graph below).
AdiSodiumTM generates less ammonia emission than sodium bicarbonate (Mercier et al. 2005)
Sodium sulphate has 32 % Na, compared to sodium bicarbonate which has 27% sodium. So 16% less product is required to reach the same DEB level because 1kg of sodium bicarbonate can be replaced by 0.84kg of sodium sulphate. With sodium sulphate, the cost of Sodium in the formulation can be reduced by at least 30% (depending on market conditions).
De Los Mozos J. and Mercier Y. Comparative effect of sodium salts on growth performance and ammonia emission under temperate or cyclic heat stress conditions. 2007. European symposium on poultry nutrition.
Hooge D.M., Cummings K.R. and McNaughton J.L. Evaluation of sodium bicarbonate, chloride, or sulfate with a coccidiostat in corn-soy or corn-soy-meat diets for broiler chickens. 1999. Poultry Science, 78:1300-1306.
Hunt J.R. Fate of ingested sodium bicarbonate in the fowl. 1970. Ann. Biol. anim. Bioch. Biophys, 10:111-118
Lawlor, P.G., Lynch, P.B., Caffrey, P.J., O’Reilly, J.J., and O’Connell, K. (2005). Measurements of the acid binding capacity of ingredients used in pig diets. Irish Veterinary Journal 58: 301-306
Mercier Y., Nuffer S. and Geraert P.A. Dietary adjustment in sodium for growing broilers: bicarbonate or sulphate? 2005. Journées de la Recherche Avicole. Mercier et al. 2005
Mongin P. Recent advances in dietary cation-anion balance : applications in poultry. 1981 Proc. Nutr. Soc (Camb), 40 : 285-294.
Reminder on DEB
Dietary electrolyte balance plays an important role in blood acid-base regulation. Electrolyte supplementation should therefore be adjusted to insure balance between H+ exchanges and HCO3- exchanges. Indeed dietary Na+ and K+ can pump out blood H+. On the contrary, dietary Cl- will aggravate the acidosis by pumping H+ in the blood and by consequence decreasing HCO3- concentration. These exchanges are due to the constant electro-neutrality of body fluids.
Impact of strong ions on acid-base balance
It is recommended to avoid any relative excess of chloride compared to sodium to compensate the metabolic acid load and alleviate regulation processes by bones or kidneys.
The DEB is therefore calculated as Na + K – Cl (Mongin et al. 1981) in mEq/kg. Other divalent ions (Ca2+, Mg2+, SO42-) could also be considered but their impact on blood pH is negligible. SO42- is not even digestible by monogastrics.
Dietary Electrolytic Balance (DEB) has been shown by numerous authors as a very important criterion to maximise animal performances. Indeed, nowadays more and more nutritionists introduce a minimum DEB level as a matrix constraint. But DEB optimization is only valuable if each electrolyte is neither deficient nor in excess in the diet.