Investigation of the interaction between separate calcium feeding and phytase supplementation on growth performance, calcium intake, nutrient digestibility and energy utilisation in broiler starters

The interaction between separate calcium (Ca) feeding and phytase supplementation on performance, coefficient of apparent ileal digestibility (CAID) of nitrogen (N), starch, fat and phosphorus (P), total tract retention (TTR) of Ca and P, and apparent metabolisable energy (AME) in broiler starters was investigated. The effect of phytase on the CAID and TTR of P in birds with access to a separate Ca source was of particular interest. Five dietary Ca concentrations (1.3, 4.3, 7.3, 10.3 and 13.3 g/kg) and two inclusion levels (0 or 1000 phytase units [FYT/kg] of feed) of a 6-phytase were evaluated in a 5 × 2 factorial arrangement of treatments. All diets, based on wheat and soybean meal, were formulated to be equivalent in respect of total and non-phytate P contents (5.7 and 3.0 g/kg, respectively). A total of 480, one-day-old male broilers were allocated to 48 cages (8 birds/cage), and cages were randomly assigned to 10 dietary treatments. Birds were also provided with a source of Ca in a separate feed trough. Increasing dietary Ca concentration decreased (P 0.05). Birds fed 1.3 g Ca/kg diet showed the lowest (P 0.05) to the diets with 4.3 g Ca/kg. No significant (P > 0.05) effect of dietary Ca concentration on the CAID of starch, fat and GE was found. Whilst, increasing dietary Ca concentration reduced (P 0.05) retention. There was no effect (P > 0.05) of dietary Ca on AME and toe ash. The previously reported Ca-specific appetite in modern broilers and the ‘phosphoric’ and ‘extra-phosphoric’ effects of phytase were confirmed in this study. Importantly, the current work highlighted the additive outcome of separate Ca feeding and phytase addition.