Influence of dietary factors on nitrogen partitioning and composition of urine and feces of fattening pigs.

An experiment was conducted to investigate the influence of dietary factors on the partitioning of nitrogen excretion and on the pH and composition of urine and feces of fattening pigs. Sixteen male hybrid pigs of 80 to 90 kg BW were allotted to one of four diets: based on grains, by-products, grains plus tapioca, or grains plus sugar beet pulp. Diets were formulated to have similar contents of NE and CP and a similar lysine:NE ratio. Diets differed in nonstarch polysaccharide content (NSP) and dietary electrolyte balance (dEB). During an 8-d period, urine and feces were quantitatively collected daily in metabolism cages and mixed to a slurry. There was no effect of the diet on total nitrogen excretion (P > .05). However, the nitrogen excretion pattern differed between diets (P < .001). Pigs fed the by-product- and the sugar beet pulp-based diets excreted less nitrogen via urine and more nitrogen via feces than pigs fed the grain- and tapioca-based diets. The type of diet significantly affected the pH of urine, feces, and slurry. The pH of slurry from pigs fed the sugar beet pulp-based diet was .44 to 1.13 units lower than that of slurry from pigs fed the other three diets. An increased dietary NSP content reduced the pH of feces and slurry. A decreased dEB reduced the pH of urine and slurry. We conclude that dietary NSP influences the partitioning of excretory nitrogen between urine and feces. Dietary NSP and dEB can influence the pH of urine, feces, and slurry.