Abstract

A total of 80 male Ross 308 broiler chickens were used in this study to quantify the response and inter-relationship of bird growth performance, dietary nitrogen corrected apparent metabolisable energy (AMEn), and nutrient digestibility as a result of feeding graded levels of supplementary myo-inositol (MYO) with and without exogenous phytase (PHY). Supplementation of diet that was formulated to be insufficient in available Phosphorus (P) with graded levels of MYO improved daily weigh gain (WG) and AMEn intake (P < 0.05; quadratic) and linearly reduced (P < 0.05) the concentration and the secretion of sialic acid (SA) in excreta. Supplementation with PHY improved (P < 0.05) dietary dry matter (DMD) and nitrogen (ND) digestibility coefficients. Dietary phosphorus digestibility (PD) increased with PHY addition as expected but the effect was much more pronounced in the low MYO group compared with high MYO diets as described by the interaction (P < 0.05). The interaction showed that increasing MYO content had no effect in the absence of PHY but it depressed P digestibility in the diets containing PHY. It can be concluded that dietary MYO improves bird growth and possibly intestinal health of broiler chickens. Dietary supplementation with either MYO or PHY may improve growth of chickens although these effects may not always be additive.