Dilger R N, Adeola O
Department of Animal Sciences, Purdue University, West Lafayette, IN 47097, USA.
Poult Sci. 2006 Apr;85(4):661-8. doi: 10.1093/ps/85.4.661.
This study evaluated regression of total P output against dietary P intake to simultaneously estimate endogenous P loss and true P utilization in broiler chicks. Soybean meal (SBM) served as the model ingredient, and a comparison was made between conventional and low-phytate SBM varieties. These feedstuffs were chosen to minimize nutritive differences to dietary phytate content. Low-phytate SBM contained 57% less phytate than conventional SBM. Four isocaloric diets were formulated to contain graded levels of each soybean meal (8 diets total); therefore, the diets also contained graded levels of dietary P. Chromium sesquioxide was included in diets as an indigestible marker, and free access to experimental diets was provided to 288 male broiler chicks from 15 to 22 d posthatch. The experiment was arranged as a randomized complete block design with 6 blocks of 8 cages (6 birds per cage) and similar initial BW across dietary treatments. As P intake ranged from 0.9 to 3.9 g/ kg of DM, apparent prececal P digestibilities increased (linear and quadratic, P < 0.01) for conventional SBM and low-phytate SBM. Increasing linear relationships (P < 0.01) were observed for total P output (mg/kg of DM intake) with graded P intake, regardless of SBM variety. True P retention was greater (P < 0.01) for low-phytate SBM (76.9%) than for conventional SBM (59.8%). Endogenous P estimates were not different between soybean meals (P > 0.10), and an overall estimate of 235 mg of P/ kg of DM intake was observed. This study concluded 1) the regression approach may be applicable in the estimation of endogenous P loss in broiler chicks and 2) the difference in P utilization between conventional and low-phytate soybean meals is influenced by dietary phytate content when broiler chicks are fed P-deficient diets.
本研究评估了总磷排出量相对于日粮磷摄入量的回归关系，以同时估算肉仔鸡的内源磷损失和真磷利用率。以豆粕（SBM）作为模型原料，并对常规豆粕和低植酸豆粕品种进行了比较。选择这些饲料原料是为了尽量减少日粮植酸含量的营养差异。低植酸豆粕的植酸含量比常规豆粕低57%。配制了四种等热量日粮，每种豆粕含有不同梯度水平（共8种日粮）；因此，日粮中的磷含量也呈梯度变化。日粮中添加了三氧化二铬作为不可消化标记物，并在15至22日龄的288只雄性肉仔鸡自由采食实验日粮。实验采用随机完全区组设计，共6个区组，每个区组8个笼子（每个笼子6只鸡），各日粮处理组的初始体重相似。随着磷摄入量从0.9克/千克干物质增加到3.9克/千克干物质，常规豆粕和低植酸豆粕的盲肠前磷表观消化率均增加（线性和二次曲线，P<0.01）。无论豆粕品种如何，随着磷摄入量梯度增加，总磷排出量（毫克/千克干物质摄入量）呈现出增加的线性关系（P<0.01）。低植酸豆粕的真磷保留率（76.9%）高于常规豆粕（59.8%）（P<0.01）。两种豆粕的内源磷估计值没有差异（P>0.10），观察到的总体估计值为235毫克磷/千克干物质摄入量。本研究得出结论：1）回归方法可能适用于估算肉仔鸡的内源磷损失；2）当给肉仔鸡饲喂低磷日粮时，常规豆粕和低植酸豆粕之间的磷利用率差异受日粮植酸含量的影响。
