Effect of feeding low phytate maize on performance, bone-breaking strength, and intestinal phosphorus transporters in slow-growing chickens during starter phase

SUMMARY: A major portion of the total P present in maize grain is in the form of phytic acid, which affects P bioavailability. The study was undertaken to determine the effect of feeding low phytate maize (LPM) with varying levels of nonphytate phosphorous (NPP) on performance, bone-breaking strength, and intestinal gene expression of phosphorous transporters in Gramapriya birds during the starter phase (up to 42 d). A total of 432 one-day-old Gramapriya chicks were randomly distributed into 6 dietary treatments having 12 replicates with 6 chicks in each replicate. The experimental diets were formulated to contain each of 3 levels of NPP (0.25, 0.33, and 0.45%) using normal maize (NM) or LPM. Higher body weight gain (BWG) and better feed conversion ratio (FCR) among the groups fed diets with LPM compared to those groups fed diets with NM. The variations in the different parameters recorded were analyzed using the general linear model multivariate procedure. The P content of the tibia was higher among the groups fed LPM-based diets compared to those groups fed NM. Na-dependent phosphate co-transporter (NaPi-IIb) expression was higher among the groups fed NM. Further, the mRNA expression of NaPi-IIb was linearly increased among the groups fed lower levels of NPP. At the ileum, the inorganic phosphate transporter-1 expression was linearly increased with decreased levels of NPP supplementation. This study demonstrated the feeding diets with LPM revealed improved BWG, FCR, and higher bone mineralization in Gramapriya birds during the starter phase. Further, it is observed that feeding diets with varying levels of NPP and NM or LPM influenced the expression profile of genes involved in the active transport of P in the small intestine of chickens.