Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA.
Poult Sci. 2013 Aug;92(8):2109-17. doi: 10.3382/ps.2013-03068.
The objectives of this study were to determine the ileal digestibility of P in potassium phosphate, phytase-related ileal digestible P release, bone-mineralization-based ileal digestible P equivalency of phytase, and phytase-related efficiency of ileal digestible P utilization for bone mineralization in broiler chickens at 2 dietary concentrations of highly soluble Ca (HSC). Birds were sorted by BW at d 15 posthatch and assigned to 8 cages per diet with 8 birds per cage. Twelve diets were arranged in a 2 × 6 factorial of HSC at 5 or 6 g/kg and P supply treatment at 6 levels consisting of 4 added P levels (P from KH2PO4 added at 0, 0.7, 1.4, or 2.1 g/kg of diet) or 2 added phytase levels (500 or 1,000 phytase units). On d 24 posthatch, ileal digesta were collected for ileal P digestibility (IPD) determination and the left tibia was collected from the 4 heaviest birds in each cage for bone ash determination. Weight gain, G:F, and tibia ash were higher (P < 0.05) at 5 than at 6 g of HSC/kg. Added P from KH2PO4 or added phytase linearly increased (P < 0.001) weight gain, G:F, tibia ash, and IPD. The IPD of KH2PO4 derived from multiple linear regressions of digestible on total P intake for the diets without added phytase showed a reduction (P < 0.05) from 89.5 to 84.5% with increased HSC from 5 to 6 g/kg. Polynomial regressions of digestible P intake on phytase intake indicated that 1,000 units of added phytase released 1.701 or 1.561 g of digestible P in diets containing 5 or 6 g of added HSC/kg, respectively. Polynomial regressions of tibia ash on digestible P or phytase intake in diets containing 5 or 6 g of added HSC/kg at 1,000 phytase units gave digestible P equivalency of 1.487 or 1.448 g, respectively. Thus, phytase-related efficiency of ileal digestible P utilization for bone mineralization was 87.4 and 92.8% in diets containing 5 or 6 g of added HSC/kg, respectively.
本研究的目的是确定钾磷酸盐中磷的回肠消化率、植酸酶相关的回肠可消化磷释放量、基于骨矿物质化的植酸酶回肠可消化磷当量和肉鸡在 2 种高水溶性钙（HSC）饲粮浓度下植酸酶相关的回肠可消化磷利用效率用于骨矿物质化。在孵出后第 15 天，根据体重对雏鸡进行分类，并将其分配到 8 个饲粮笼中，每个笼中 8 只鸡。12 种饲粮采用 HSC （5 或 6 g/kg）和磷供应处理的 2×6 因子设计，磷供应处理由 4 个添加磷水平（KH2PO4 来源的磷分别添加 0、0.7、1.4 或 2.1 g/kg 饲粮）或 2 个添加植酸酶水平（500 或 1000 植酸酶单位）组成。在孵出后第 24 天，收集回肠食糜进行回肠磷消化率（IPD）测定，从每个笼中 4 只最重的鸡中收集左胫骨进行骨灰分测定。5 g/kg 的 HSC 比 6 g/kg 的 HSC 体重增加（P<0.05）、饲料效率（G:F）和胫骨灰分更高。来自 KH2PO4 的添加磷或添加植酸酶线性增加（P<0.001）体重增加、饲料效率、胫骨灰分和 IPD。无添加植酸酶的饲粮中总磷摄入量的可消化磷的多元线性回归表明，HSC 从 5 g/kg 增加到 6 g/kg，KH2PO4 的 IPD 从 89.5%降低到 84.5%（P<0.05）。添加植酸酶摄入量的可消化磷摄入量的多项式回归表明，在含有 5 或 6 g/kg 添加 HSC 的饲粮中，添加的 1000 个单位的植酸酶分别释放 1.701 或 1.561 g 可消化磷。在含有 5 或 6 g/kg 添加 HSC 的饲粮中，胫骨灰分的可消化磷或植酸酶摄入量的多项式回归在 1000 个单位的植酸酶下分别得到 1.487 或 1.448 g 的可消化磷当量。因此，在含有 5 或 6 g/kg 添加 HSC 的饲粮中，植酸酶相关的回肠可消化磷用于骨矿物质化的效率分别为 87.4%和 92.8%。
