Nutritional studies on phosphorus in broiler diets

The present study was carried out within two identical experiments to examine the possible adaptation for gradual deficient dietary non-phytate phosphorus (NPP) and calcium (Ca) in existence of extra vitamin D3 levels in broiler diets, on productive performance,NPP and Ca retention, plasma levels of Ca and P, bone measurements and economic efficiency . 240 unsexed I day old Hubbard broiler chicks were randomly distributed into 6 treatments.There are 3 starter diets: . Control (C) 1.000% Ca and 0.500% NPP with D3 3000IU/ Kg . Medium (M) 0.750% Ca and 0.375% NPP with D3 5000 IU/Kg . Low (L) 0.500% Ca and 0.250%NPP with D3 7000 IU/ Kg .There are also 3 grower diets:. Control (C) 0.900% Ca and 0.450% NPP with D3 3000 IU/ Kg . Medium (M) 0.650% Ca and 0.325% NPP with D3 6000 IU/Kg . Low (L) 0.400% Ca and 0.200% NPP with D3 9000 IU/ Kg Six dietary treatments were distributed according to what birds were fed consecutively during starter and grower phases as (C/C),(C/M), (C/L), (M/M), (M/L) and (L/L) diet. Each treatment comprised of 40 chicks which were split into 4 replicates of 10 chicks each.Results of the first experiment showed that live body weight (LBW) values for birds fed either (C/C) or (C/M) diet were heavier than of those fed (C/L) diet. Body weight gain (BWG) of birds fed (C/M) diet was larger than of those fed (C/L) diet. Birds fed (C/M) diet consumed more feed than of those fed (M/M) diet. Feed conversion ratio (FCR) of birds fed either (C/C) or (C/M) diet were better than of those fed (C/L) diet. Dressing percentage (DP) values appeared significantly similar among different dietary treatments Plasma Ca concentrations indicated that birds fed either (C/C) or (C/M) diet have higher values than of those fed (C/L) diet. Plasma P levels of birds fed (C/C) diet was higher than of those fed (C/L) diet. Plasma alkaline phosphatase (ALP) activity indicated that birds fed (C/L) diet have the highest value. Dry tibia weight (DTW) percentage appeared similar among different dietary treatments. Tibia ash, Ca and P percentages for birds fed either (C/C) or (C/M) diet, were higher than those fed (C/L) diet. Birds fed either (C/M), (M/L) or (L/L) diet have longer tibiae than of those fed (C/L) diet. Also, Birds fed (L/L) diet have broader tibiae than of those fed (C/L) diet. Tibia seedor index (SI) values showed that birds fed (C/L) diet have the lowest value among different dietary treatments. While, tibia breaking strength (TBS) values indicated that, birds fed either (C/C) or (C/M) diet have stronger tibiae than of those fed (C/L) or (M/L) diet. Ca and P retention percentages of birds fed (C/L), (M/L) or (L/L) diet were higher than of those fed (C/C) diet. Economic efficiency (EE) values appeared significantly similar among different dietary treatments. On the other hand, production efficiency factor (PEF) of birds fed (C/M) diet was better than of those fed (C/L). Results of the second experiment showed that LBW values for birds fed (C/C) diet were heavier than those fed (C/L) diet. BWG of birds fed (C/M) diet was larger than of those fed (C/L) diet. Data of daily feed consumption (DFC) indicated that all birds consumed significantly equal amount of feed. FCR of birds fed (C/C), (M/L) or (L/L) diet were better than those fed (C/L) diet. Values of DP appeared significantly similar among different dietary treatments. Plasma Ca levels indicated that birds fed either (C/C) Or (C/M) diet have higher levels than of those fed (C/L) diet. Plasma P levels of birds fed (C/C) or (C/M) diet was higher than of those fed (C/L) diet. Plasma ALP activity indicated that birds fed (C/L) diet have the highest value and birds fed (C/C) diet showed the lowest activity value. Dry tibia weight (DTW) percentage appeared significantly similar among different dietary treatments. Additionally, tibia ash, Ca and P percentages for birds fed (C/C) diet were higher than those fed (C/L) diet. Birds fed (C/C) diet have longer tibiae than of those fed other diets which had similar values. Moreover, tibia width values appeared significantly similar among different dietary treatments. While, TBS values indicated that birds fed either (CIC) or (C/M) diet have stronger tibiae than of those fed (C/L) or (M/L) diet. Tibia SI values showed that birds fed either (C/C) or (C/M) diet, have higher values than those fed (C/L) diet. While TBS values indicated that birds fed (C/C) or (C/M) diet have stronger tibiae than those fed (C/L) or (M/L) diet. Ca and P retention percentages of birds fed either (M/L) or (L/L) diet were higher than of those fed (C/C) diet. Birds fed (L/L)diet recorded the best EE compared to those fed (C/L). PEF of birds fed either (C/C) or (C/M) diet was better than of those fed (C/L).We recommend using less than half of common requirements of Ca and NPP in broiler diets supplemented with extra levels of vitamin D3 (9000 I.U./ Kg), as in (L/L) treatment, in order to diminish feed costs as well as to lessen P emission in the environment devoid of any unfavorable effects on performance, carcass, blood and bone features. Finally, we recommend that Ca and P requirements have to be re-estimated over again.