Possibilities to lower the nitrogen and ammonia emissions in growing pigs by adjusting the feed composition

Three different feeding systems were applied for each of which the protein content decreased differently in time, Urine and faeces were collected sepa rately in metabolism cages without volatilisation of ammonia to determine t he daily amount of nitrogen retained and excreted. In the stable the litter was collected after ammonia volatilisation. The samples were analysed for nitrogen. The three feeding systems did not differ in growth, feed conversion or carc ass composition. The nitrogen retention was higher in gilts than in barrows . The percentage nitrogen emission through urine increased with age; the fa ecal nitrogen emission stayed unchanged. The reduction of feed nitrogen red uced the total nitrogen emission by the decrease of the urinary nitrogen em ission. As a consequence, the potential ammonia-emission was reduced. The supply of protein-poor feed and multi-phase feeding is a valid option t o lower nitrogen and ammonia emissions in growing pigs.