A study for reduction of phosphorus output from ruminant livestock waste

点击翻译按钮获取中文摘要

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.