ISSUE FOCUS 56 FEED & ADDITIVE MAGAZINE February 2026 EXAMPLES OF GETTING CALCIUM AND PHOSPHORUS RIGHT Calcium (Ca) and phosphorus (P) are the most abundant mineral elements in the body. Most of the body’s Ca and P is stored in the skeleton which is why these minerals are so closely linked to bone health and skeletal integrity. But Ca and P are also involved in several other important pathways such as energy metabolism, blood clotting and neuromuscular function. Insufficient levels or an inadequate ratio of these minerals in the diet can cause several problems such as rickets, tibial dyschondroplasia, lameness, nerve function problems, poor appetite and body weight uniformity. Total blood Ca is typically around 11.5-12 mg/dL, and P is usually approximately 6-7 mg/dL (Figure 5). Approximately 47-48% of blood Ca is ‘ionized’ (metabolically active; Figure 4), whereas the remainder of blood Ca is covalently bound to plasma proteins or associated with anions such as phosphate or lactate. These concentrations do not substantially change with bird age or gender but can be disrupted by various nutrition and management factors. For example, ionized Ca has been observed as low as 0.6 mmol/l. Birds with levels of ionized Ca as low as this will display atypical behaviour, nervous paralysis and elevated mortality. More often, subclinical hypocalcemia or hypophosphataemia are observed, which is associated with low body weight (Figure 6) and poor flock uniformity. 0 5 10 15 20 25 30 35 40 45 50 55 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 Age Mean of ii Ca Figure 3. Typical levels of ionized calcium (mmol/l) found in the blood of broilers (Source: dsmfirmenich, 2023) variable vCA vPHOS 14 12 10 8 6 4 2 0 Mean of Ca & P Age 0 5 10 15 20 25 30 35 40 45 50 55 60 Figure 4. Mean plasma calcium (mg/dL) and phosphorus (mg/dL) concentrations in the blood of broilers (Source: dsm-firmenich, 2023)
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