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Effects of the Level and Relationship of Calcium and Available Phosphorus on the Growth and Tibia Mineralization of Broiler Starter Chickens

2019; Elsevier BV; Volume: 28; Issue: 2 Linguagem: Inglês

10.3382/japr/pfy077

1542-6629

J.A. Díaz-Alonso, Sergio Gómez-Rosales, M.deL. Angeles, Ernesto Ávila‐González, Carlos López-Coello,

Selenium in Biological Systems

The objective of this research was to evaluate the growth performance and tibia measurements in broilers from 8 to 21 d of age fed diets with increasing levels of aP at adjusted or variable levels of Ca. A total of 168 chicks from 8 to 19 d of age were allocated in pairs per cage and randomly assigned to 6 dietary levels of aP (0.13%, 0.23%, 0.33%, 0.43%, 0.53%, and 0.63%) and 2 Ca:aP ratios, adjusted (adjCa:aP) or variable (varCa:aP). In the AdjCa diets, the Ca:aP ratio was kept at 2:1; in the varCa diets the Ca:aP ratio varied from 7.69 to 1.59. Chicks were weighed at the beginning and end of the experiment. At the last day of the trial, all chicks were killed to determine the tibia ash and Ca and P content in the ash. Data was subjected to ANOVA and linear regression analysis. In broilers fed the adjCa:aP diets, the maximum WG, weight of tibia ash, and weight of P in tibia ash (P < 0.01) were observed at aP levels of 0.40%, 0.52%, and 0.53% aP, and at aP levels of 0.63%, 0.62%, and 0.59% in broilers fed the varCa:aP diets. Broilers fed the adjCa:aP ratio diets had higher (P < 0.01) aP intake, aP intake per g of WG, tibia ash percentage, weight of Ca, and percentage P in tibia ash, but lower feed conversion ratio compared to broilers fed the varCa:aP ratio diets. Regardless of the dietary Ca:aP ratios, the maximum tibia ash percentage (P < 0.01), weight of Ca in tibia (P < 0.01) and percentage of P in tibia (P < 0.05) were estimated at 0.59%, 0.62%, and 0.57% aP. The maximum WG, weight of ash, and Ca and P on tibia ash were reached in broilers fed diets with an aP level of 0.53% and Ca:aP ratio of 2:1 and in those fed diets with an aP level of 0.63% and Ca:aP ratio of 1.59.