Impact of nutrition on reduction of environmental pollution by pigs: an overview of recent research.

This paper focuses on research with pigs carried out primarily at the ID-DLO in the Netherlands with the aim to reduce environmental pollution with nitrogen and phosphorus by changing the diet of the animals while maintaining their health and performance. The excretion of phosphorus (P) per growing pig has been more than halved in the last 20 years as a result of intensive nutritional research on P digestibility, requirements for P, and on the efficacy of microbial phytase in pig feeds. Also, nitrogen (N) excretion can be reduced substantially, but this knowledge has not been put into practice as yet. Preliminary results show that ammonia production can be reduced considerably by altering the diet. Studies to reduce the overproduction of sow manure (up to 98% water) showed that voluntary water consumption by non-pregnant sows under thermal neutral conditions was approximately 1.4 higher than the requirements. A water:feed ratio of 2:1 for pregnant sows kept at an ambient temperature of 18-20 degrees C had no detrimental effect on health and nutrient digestibility, but diminished urine production by 3.6 L/day, as compared to that with ad libitum water consumption.