Morphometry and mineralization of tibia bone as influenced by dietary phosphorus levels and depletion in finishing broiler chickens

An experiment was conducted to study the effect of feeding different levels of phosphorus and its subsequent depletion at varied levels on tibia bone morphometry and mineralization of finishing broiler chickens. Initially, three test diets were prepared by supplementing dicalcium phosphate to basal diet to achieve 0.3, 0.4 and 0.5% available phosphorus (AP) for starter phase (0-21d) by introducing each diet in twelve groups having nine chicks each. Nine more test diets were also prepared by depleting 0, 25, 50 and 75% of P of each diet that had been tested during starting phase. Thus, during finishing phase (22–42 d), 12 test diets were evaluated in a factorial manner (3x4). At the end of 42 d, 72 tibia bone (6 per treatment) were collected for measurement of morphometry and mineralization. The bone length, width at long axis and short axis, fresh bone weight, percent bone ash and bone calcium did not differ significantly due to either main effect or different dietary combinations. Whereas, higher (P<0.05) dried bone weight and bone P were observed at higher AP levels than lower levels between 22–42 d. Dried bone weight and bone P contents did not differ significantly due to depletion of P and interaction of AP levels and depletion. It was concluded that the phosphorus levels in broiler finisher diet can be kept upto 50% depletion at 0.15% available phosphorus during finishing phase (22–42 d) for optimum bone parameters studies.