Effects of phytase supplementation on eggshell and bone quality, and phosphorus and calcium digestibility in laying hens from 25 to 37 wk of age

Abstract

Effects of dietary available phosphorus (aP) and Ca levels and an Escherichia coli 6-phytase supplementation were studied in Lohmann LSL-Lite hens from 25 to 37 wk of age. Eighty-four hens were used in a completely randomized design with 7 treatments. The treatments were a positive control (PC) diet with 0.45% aP, 3.70% Ca, and 0.16% Na from 25 to 28 wk and 0.38% aP, 3.73% Ca, and 0.15% Na from 29 to 37 wk; a negative control (NC) diet, similar to the PC diet, with 0.22% aP, 3.00% Ca, and 0.13% Na from 25 to 28 wk and 0.19% aP, 3.02% Ca, and 0.13% Na from 29 to 37 wk; the NC diets supplemented with phytase at 150 (NC + 150), 300 (NC + 300), 600 (NC + 600), or 1,200 (NC + 1,200) phytase unit (FTU)/kg; and the PC diet supplemented with phytase at 1,200 (PC + 1,200) FTU/kg. Hen performance, eggshell, and bone quality were measured on a 4-wk basis. Bone breaking strength and ash and apparent ileal digestibility (AID) of P and Ca were determined at 37 wk. One- and 2-way ANOVA were conducted, and Tukey's range test was used to compare multiple means where P ≤ 0.05. No differences in hen performance, eggshell quality, bone breaking strength, bone ash, and P digestibility were observed between the PC and the NC treatments. The NC hens had lower cortical (P < 0.001) and trabecular + medullary bone mineral density (P = 0.004) and total bone mineral content (P < 0.001) than the PC hens. The PC + 1,200 increased cortical bone mineral density (P < 0.001). The reductions of aP and Ca in the NC diet were not deficient for performance but had a minor impact on bone mineralization. The NC + 600 and NC + 1,200 increased AID of P (P = 0.024), and all phytase treatments except the NC + 150 increased AID of Ca (P = 0.010) compared with the NC diet.

Keywords: P and Ca digestibility; bone; eggshell; laying hen; phytase.

Figure 1

Effect of dietary aP and Ca and phytase supplementation on (A) apparent ileal digestibility (AID) of P (P = 0.024; n = 84) and (B) AID of Ca (P = 0.010; n = 84) at 37 wk of age. Apparent ileal digestibility of P and Ca was determined from 35 to 37 wk of age. A positive control (PC) diet, nutritionally complete diet containing 0.45% aP, 3.70% Ca, and 0.16% Na (25–28 wk) and 0.38% aP, 3.73% Ca, and 0.15% Na (29–37 wk); NC, a negative control diet, similar to the PC diet but having 0.22% aP, 3.00% Ca, and 0.13% Na (25–28 wk) and 0.19% aP, 3.02% Ca, and 0.13% Na (29–37 wk); NC + 150, NC + 300, NC + 600, and NC + 1,200, the NC diet supplemented with 150, 300, 600, or 1,200 FTU Quantum Blue phytase (AB Vista, Marlborough, UK)/kg, respectively; and PC + 1,200, the PC diet supplemented with 1,200 FTU Quantum Blue phytase/kg. Data are presented as least squares means with the respective standard errors of the mean. ^a,bMeans within treatment with no common superscript differ significantly (P ≤ 0.05).