Interactive effects of calcium, vitamin D3, and exogenous phytase on phosphorus utilization in male broiler chickens from 1 to 21 days post-hatch: A meta-analysis approach

Abstract

Provision of appropriate dietary phosphorus (P) content considering environmental and economic aspects has been challenging for poultry nutritionists during the last decades. For this reason, many studies have focused on factors affecting P utilization in broiler chickens, such as calcium (Ca), cholecalciferol (vitamin D3; VD), and exogenous phytase (EP), but their results have sometimes been accompanied by inconsistencies. Therefore, comprehensive knowledge of the factors affecting P utilization and their interactions is required to draw conclusions from the available results. For this purpose, a meta-analysis was conducted using 79 studies including 719 experimental treatments published between 2011 and 2021, which considered the effects of Ca, EP, and VD on P utilization in male broiler chickens from 1 to 21 days post-hatch. The collected data were fitted well to a mixed model for average daily gain (ADG; R2 = 0.941), average daily feed intake (ADFI; R2 = 0.956), feed conversion ratio (FCR; R2 = 0.989), and tibia ash (TA) content (R2 = 0.984). Linear and quadratic effects of dietary non-phytate P (NPP) content on ADG, ADFI, FCR, and TA content were observed (P < 0.001). Also, results showed the linear and quadratic effects of EP on ADG, FCR, and TA content (P < 0.001). The ADG (P < 0.01) and TA content (P < 0.05) were affected by VD supplementation. The fitted models showed that the increase in dietary Ca content linearly exacerbated all responses (P < 0.001), but such negative effects were alleviated with the increase in dietary NPP content and EP and, or VD addition due to their interactions. Results of the optimization process showed that simultaneous addition of EP and VD resulted in lower NPP concentration required to optimize growth performance and TA content compared to separate supplementation. Also, increasing dietary level of EP (up to 2000 FTU/kg of diet) reduced NPP requirement for optimal growth performance and bone mineralization. It can be concluded that Ca, EP, and VD affect the NPP requirements of broiler chickens, but the magnitude of these effects varies depending on the studied criterion.