Effects of low-protein diet including raw potato starch on nitrogen excretion and ammonia emission in finishing pigs

Abstract

This experiment was designed to assess the effects of a low-protein diet including raw potato starch (RPS) on nitrogen excretion and ammonia emission in finishing pigs. Four castrated male pigs (WLD, 64.0kg) were used for a crossover nitrogen balance study, and another 8 castrated male pigs (WLD, 70.0kg) were for an ammonia emission study in the windowless pigpen. Pigs in each study were divided into two groups, the control group fed with a conventional fattening diet (CP15.7%) and the treatment group fed with a low-protein diet (CP11.6%) containing 20% RSP. Although the dietary treatment with low-protein RPS increased the fecal nitrogen content (P<0.01), the treatment reduced the urinary and total (urinary and fecal) nitrogen contents (P<0.01). The amount of in vitro ammonia emission from the excreta mixture was lower in the low-protein RPS treated pigs than in the control pigs (P<0.05). The ammonia concentration in the windowless pigpen was also less in the low-protein RPS feeding (P<0.01). There were no differences in the growth rate, feed intake and feed conversion ratio between the two experimental groups. These results suggested that RPS is an effective ingredient in the diet for pig fattening because it reduces the nitrogen excretion that is detrimental to the environment.