The trend of studies on reducing nutrient excretion in poultry and pigs by nutritional approaches

摘要

It has been pointed out that livestock manure is becoming an increasing burden on the environment. The aim of this paper was to search the trend of recent studies on reducing nutrient excretion in poultry and pigs by means of nutrition. The resultsobtained are summarized as follows. 1. It is possible to reduce the amounts of feces excreted in poultry and pigs by improving nutrient digestibilities via enzymes addition (cellulase, protease) and processing of diet (pellet, expander). The amounts of urine excreted in pigs are reduced by about 40 approx 50 percent by feeding amino acids supplemented-low protein diets. 2. It is possible to reduce the nitrogen (N) excretion by about 30 percent 10 percent and 20 percent in pigs, broilers and laying hens,respectively, by feeding amino acids supplemented-low protein diets without a decline in productivity. The reason for the low reducing rate of N excretion in broilers is that it is unable to reduce largely dietary protein level because abdominal fat accumulation increases in broilers fed low protein diets. Further experiments on this point are necessary. 3. It is possible to reduce phosphorus (P) excretion by about 30 percent in both pigs and laying hens and by about 40 percent in broilers by feeding low-P diets supplemended with niicrobial phytase (Aspergillus niger) without a decline in productivity. 4. Recent studies suggest that the amounts of copper (Cu) and zinc (Zn) supplemented to the diets during weaning and growing periods in pigs may be reduced without negative effect on growth-promotion of Cu for young pigs and therefore Cu and Zn excretions decrease. Further studies on this problem are necessary.