Nutritional possibilities to reduce the N and P excretion of pigs (A review)

Abstract

Manure disposal is a major problem in highly intensive pig production areas, especially for nitrogen and phosphorus, because of water and air pollution. Among farm animals the monogastric species excrete most of the nitrogen and phosphorus, due to the digestibility properties, protein and amino acid supply and improper manure handling. Sows, weaners and slaughter pigs excrete approximately 75%, 45% and 70% of the nitrogen, and 75%, 40% and 60% of the phosphorus consumed, respectively. In total about 34000 ton N and 8000 ton P can potentially pollute the environment yearly from the pig and poultry sector in Hungary. Therefore, it is important to reduce the amount of these elements in the manure and urine. Our objective was to discuss the nutritional possibilities to reduce N and P excretion of pig farming in Hungary. The potential N and P pollution in Hungary is about 5.0 and 1.1 kg per ha of arable land, respectively. These values are far below the legislation in France, Denmark and The Netherlands (Jongbloed et al., 1999). However, by improper manure and slimy handling the regional emission can be even higher. In Hungary the introduction of dietary nutrient recommendations based on ildeal digestible amino acids, ideal protein concept and digestible phosphorus is in progress. Therefore, about 20-percentage reduction in N excretion can be expected. Shifting recommendation from total P to digestible P will not reduce significantly the P emission. Since the P emission per ha is quite low in Hungary and legislation is not foreseen, the dietary inclusion of microbial phytase will depend on economical considerations.