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Title:Effects of dietary calcium to non-phytate phosphorus ratio and phytase supplementation on growth performance, digestibility, and bone characteristics of broiler chickens
Author(s):Gautier, Alyson Elaine
Advisor(s):Dilger, Ryan N.
Contributor(s):Stein, Hans H.; Parsons, Carl M.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:Three experiments were conducted to evaluate the interrelationships among Ca, non-phytate phosphorus (NPP), and phytase supplementation in diets fed to broiler chickens. Experiment 1 was conducted to evaluate the influence of dietary Ca concentrations by evaluating growth performance, tibia measurements, and apparent retention of broiler chicks. Dietary treatments consisted of 7 concentrations of Ca (0.4, 0.6, 0.8, 1.0, 1.2, 1.4, or 1.6% of the diet) and NPP concentrations were maintained at 0.3%. Growth performance and bone ash of broilers fed 0.6% Ca were improved compared with those fed higher Ca concentrations. Tibia ash and tibia break force were reduced in birds fed Ca inclusions above 0.6%. Tibia reference force indentation measurements exhibited quadratic responses as the Ca inclusion increased from 0.4 to 1.6%. Dietary treatment effects were observed for apparent retention of P and Ca, which decreased linearly or quadratically with increasing Ca concentrations. Experiment 2 evaluated effects of dietary Ca and NPP combinations to create distinct Ca-to-NPP ratios on growth performance, tibia measurements, and apparent nutrient retention in broiler chicks. Dietary treatments contained 3 concentrations of Ca (0.4, 1.0, or 1.6% of the diet) with NPP concentrations either constant at 0.45% or adjusted to maintain a Ca-to-NPP ratio of 2:1 (6 treatments total). No growth performance outcomes were influenced by either Ca concentration or the Ca-to-NPP ratio. Maintaining a constant 2:1 Ca-to-NPP ratio, tibia break force and ash improved as Ca and NPP concentrations increased. Moreover, apparent retention of Ca decreased with increasing Ca concentration and apparent retention of P reduced as the concentrations of Ca and NPP increased. In Experiment 3, the effects of supplementing exogenous phytase in diets of varying Ca and NPP concentrations on growth performance, tibia and organ P concentrations, and apparent nutrient digestibility and retention were evaluated in broiler chicks. Chicks received 1 of 6 dietary treatments that consisted of [control diet with 1.0% Ca and 0.5% NPP; mineral matrix 1 with reductions of 0.15% NPP and 0.16% Ca compared with control; and mineral matrix 2 with reductions of 0.21% NPP and 0.23% Ca compared with control] and phytase supplementation (0 or 1,500 FTU/kg). Phytase supplementation increased BW gain, however, feed efficiency was not influenced by mineral matrix, phytase addition, or their interaction. Feed intake was quadratically influenced by the mineral matrix, but there was no effect of phytase or their interaction. The impact of phytase on tibia ash varied among the dietary mineral matrices, and tibia P content was highest in the control dietary treatment. In contrast to tibia P, concentrations of P in muscle, liver, and spleen were not influenced by dietary treatment. Various interactions among mineral matrix and phytase supplementation were observed for apparent ileal nutrient digestibility and apparent retention values. Overall, results of this research demonstrates that Ca and NPP concentrations, as well their ratio, influenced broiler growth performance, apparent nutrient digestibility and retention, and bone responses in broiler chicks.  
Issue Date:2016-07-19
Rights Information:Copyright 2016 Alyson Gautier
Date Available in IDEALS:2016-11-10
Date Deposited:2016-08

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