Nutrient management is becoming increasingly important for sustainability of the swine industry. Nitrogen excretion in the form of ammonia is a concern for workers both within the barn and outside. Phosphorous is excreted in urine and faeces and could have a major environmental impact if not managed properly. The two projects discussed in this article focussed on specific dietary manipulations to alter nutrient excretions. The first project investigated two nutritional strategies, dietary particle size reduction and enzyme supplementation as means to increase nutrient digestibility and thereby reduce nitrogen and phosphorous excretion. The second project investigated reducing dietary protein and fermentable fibre as means to alter nitrogen excretion.
Reducing particle size below 700 mm proved effective in altering nitrogen excretion patterns, while phytase proved very effective in improving digestibility of dietary phosphorus. The addition of carbohydrase showed little evidence of reducing total nitrogen or phosphorus excretion. A reduction of dietary protein content while balancing for digestible amino acids will especially reduce nitrogen excretion in urine. With dietary fermentable fibre, part of urinary nitrogen excretion can be shifted toward nitrogen excretion in faeces, and thus reduces volatile nitrogen that contributes to bad air quality. The reduction in excess nutrients and odour emissions while sustaining high levels of pork production is critical for long-term survival of a globally competitive pork industry. Together, results indicate that nitrogen and phosphorus excretion patterns can indeed be altered by diet manipulation