Holcombe D J, Roland D A, Harms R H
Poult Sci. 1976 Jan;55(1):308-17. doi: 10.3382/ps.0550308.
Two experiments were conducted to determine the extent and ability of laying hens to regulate their phosphorus (P) intake when offered a choice of diets containing different levels of phosphorus. In the first experiment, Babcock B-300 hens, 72 weeks old, received a choice of diets offered in each of two plastic cups. The dietary choices of P levels included: 0.75 percent P vs. 0.75 percent P diet (control), 0.19 percent vs. 0.46 percent P, 1.00 percent vs. 2.43 percent P and 0.19 percent vs. 2.43 percent P diet. The cups were weighed and replenished every three days. After one month, the calcium level in all diets was increased from 3.00 to 6.00 percent calcium and the experiment continued for a second month. The second experiment involved the same dietary choices of P with a constant level of 3.00 percent calcium. Hens in this experiment were 48 weeks old. In both Experiments 1 and 2 the daily feed consumption was determined by weighing all cups at two hour intervals for two days. This procedure was performed after hens had been on the experimental regime for one month. Hens in both experiments clearly regulated their intake of P when offered the above choices. Hens avoided the consumption of the 2.43 percent P diet in favor of the diet containing less P. Consumption of the 2.43 percent P diet, even when avoided to a large extent, reduced both egg production and egg specific gravity. Increased calcium levels in the diets resulted in an increase in consumption of the 2.43 percent P diet. Young hens demonstrated a significant increase in consumption of the 0.46 percent P diet over the 0.19 percent P diet. Both old and young hens in the 0.46 percent P vs. 0.19 percent P group in both experiments maintained egg specific gravity, egg weight and egg production at levels comparable to controls. Results of the two hour feed weighings showed that laying hens in the 0.19% vs. 2.43% P group exhibited a noon-time peak in preferential consumption of P, followed by a marked afternoon-evening decline. This decline occurs both for relative and absolute P intake.
进行了两项实验，以确定产蛋母鸡在可选择不同磷（P）含量日粮时调节磷摄入量的程度和能力。在第一个实验中，72周龄的巴布考克B - 300母鸡可以在两个塑料杯中选择日粮。磷水平的日粮选择包括：0.75%磷对0.75%磷日粮（对照）、0.19%对0.46%磷、1.00%对2.43%磷以及0.19%对2.43%磷日粮。每三天对杯子称重并补充日粮。一个月后，所有日粮中的钙水平从3.00%提高到6.00%钙，并继续实验第二个月。第二个实验涉及相同的磷日粮选择，钙水平恒定为3.00%。该实验中的母鸡为48周龄。在实验1和实验2中，通过每隔两小时称一次所有杯子的重量，持续两天来确定每日采食量。此程序在母鸡进入实验方案一个月后进行。在上述选择条件下，两个实验中的母鸡都明显调节了它们的磷摄入量。母鸡避免食用2.43%磷的日粮，而选择含磷量较低的日粮。即使在很大程度上被避免，食用2.43%磷的日粮仍会降低产蛋量和蛋的比重。日粮中钙水平的提高导致2.43%磷日粮的消耗量增加。与0.19%磷日粮相比，年轻母鸡对0.46%磷日粮的消耗量显著增加。在两个实验中，0.46%磷对0.19%磷组的老母鸡和年轻母鸡的蛋比重、蛋重和产蛋量均维持在与对照组相当的水平。两小时采食量称重结果表明，0.19%对2.43%磷组的产蛋母鸡在中午时分对磷的优先消耗量达到峰值，随后在下午至傍晚明显下降。这种下降在相对和绝对磷摄入量方面均会出现。
