SUSTAINABILITY FEED & ADDITIVE MAGAZINE June 2024 59 To assess environmental footprint, we have adopted the Life Cycle Assessments (LCA) methodology. As AdiSodium is a coproduct of methionine with a relatively low value versus the main product, the economic allocation of the global carbon footprint is extremely favorable to the coproduct. This explains why, among all chloride-free sodium sources, AdiSodium has an extremely low climate change value per sodium unit. This LCA report on AdiSodium has finally a value for feed millers who can include these data in their own feeds’ life cycle assessments. But the full benefit really lies in the integration of the positive impact of AdiSodium on the sustainability of animal production. DIETARY ELECTROLYTES CONSIDERATIONS IN EVOLVING FEED FORMULATIONS TO ENSURE SUSTAINABLE ANIMAL PERFORMANCE Dietary electrolytes supply and its relationship with plasmatic Acid-Base homeostasis have been studied in broilers in the early 80’s by Mongin. The relationship between the monovalent ions Na+, Cl- and K+ with the blood pH was clearly established and explained through physiological processes. This effect is, on one hand, related to absorption and ions exchanges at intestinal level with K+ and Na+ playing alkalogenic effect by exchanging with H+, whereas Cl- is acidogenic by exchanging with HCO3 -. On a second hand, this effect is due to cations / anions balance, mainly summarized to Na+ and Cl- at plasma level, that manage the required room for the carbonate buffering system. According to these works, the weighed sum of these mains ions, called Dietary Electrolytic Balance (DEB) and expressed as mEq/kg of feed, was recommended in the range of 220-240 for broilers as an optimum value to ensure optimal growth rate and Feed Conversion Ratio (FCR). However, since that time, feed formulation constraints (strategies), raw materials and synthetic amino availability have changed significantly leading to reduce and substitute soybean meal inclusion in broiler’s feed. Potassium is the only electrolyte that is not specifically supplemented in the diet, meaning its level in feed depends on the used cereals and oilseed-meals and their inclusion rates. Among these raw materials, soybean meal is by far the richest in potassium and all strategies resulting in soybean meal inclusion rate reduction will result also in a DEB decrease. On top of that, crude protein and/or soybean meal substitution mechanically increases the inclusion of lysine that, if supplemented under hydrochloride form, participates also to decrease the DEB value. Thus, maintaining the previously determined DEB target of 220 mEq/kg of feed is not affordable (reachable) anymore. REVISITING DEB TARGET VALUE IN LOW PROTEIN DIET STRATEGY Beyond economic and environmental questions, animal physiology and blood pH regulation continue to follow the same rules and the electrolytes balance needs to be maintained to ensure proper homeostasis. A recent study set-up at the Scottish Agricultural College proposes to address the question of determining the minimum dietary potassium level and re-address the optimum DEB value for broilers in a context of low Crude Protein diet (17.5%). The first outcomes are that the minimum potassium level is in between 0.63 – 0.7 % and increasing potassium level above this value has no
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