A study for reduction of phosphorus output from ruminant livestock waste

由于来源于植物的植酸盐很容易在瘤胃中被降解，因此植酸磷在反刍动物中的利用率很高。最近，人们用甲醛处理或烘焙来降低油粕的瘤胃降解率，从而提高了这些油粕中蛋白质的利用率。另一方面，这些处理可能抑制了植酸盐的瘤胃降解，因为植酸盐与这些油料粕中的蛋白质强烈结合。首先，我们使用尼龙袋技术研究了处理油料粕中植酸盐的瘤胃降解率。这项研究表明，这些处理都降低了蛋白质和植酸在两种油料粕中的瘤胃降解率，这表明这些处理抑制了反刍动物对植酸的利用。在第二个实验中，我们给绵羊饲喂烘烤菜籽粕，并测定了十二指肠消化中植酸的流量。本试验表明，菜籽粕中的部分植酸没有在瘤胃内降解，增加了植酸进入十二指肠的流量。应尽量减少饮食中的磷，以减少磷排泄到粪便中。在这种情况下，当反刍动物饲喂甲醛或烘焙处理的油籽粉时，必须考虑磷的有效性。在第三个实验中，我们研究了需要大量磷的哺乳奶牛的磷源。我们将乳清作为磷源喂给哺乳奶牛，并将乳清中磷的利用率与磷酸氢钙进行了比较。日粮磷水平控制在其需要量的下限。饲喂乳清和磷酸氢钙的奶牛产奶量和血清磷浓度没有差异，说明乳清和磷酸氢钙对磷的利用率没有差异。

Because dietary phytate originated from plant is easily degraded in the rumen, the availability of phytate phosphorus has been considered to be high in ruminants. Recently, oilseed meals became treated with formaldehyde or roasted to reduce the degradability in the rumen, which improved the availability of protein in these oilseed meals. On the other hand, these treatments are possibly suppressed ruminal degradation of phytate because phytate strongly bound to protein in these oilseed meals.Firstly, we studied ruminal degradability of phytate in the treated oilseed meals using a nylon bag technique. This study showed that ruminal degradation of protein and phytate were reduced by these treatments in both the oilseed meals and suggested that these treatments suppressed phytate availability in the ruminants.In the second experiment, we fed roasted rape seed meals to sheep and the flow of phytate was determined in the duodenal digesta. This experiment indicated that some of phytate in rape seed meal was not degraded in the rumen and the treatment increased the flow of phytate into the duodenum. Dietary phosphate should be minimized to reduce phosphorus excretion into feces. In this situation, phosphorus availability must be considered when ruminants are given oilseed meals treated with formaldehyde or roasting.In the third experiment, we studied phosphorus sources for lactating dairy cows that needed much phosphorus. We fed whey to lactating cows as a phosphorus source and the availability of phosphorus in whey was compared to dicalcium phosphate. The level of dietary phosphorus was controlled to the lower limit of its requirement. Milk production and serum phosphorus concentration did not differ between cows given whey and dicalcium phosphate, which suggested that the availability of phosphorus was not different between whey and dicalcium phosphate.