Interactions between phosphorus feeding strategies for pigs and dairy cows and separation efficiency of slurry.
Phosphorus (P) in manure is a nutrient source for plants, but surplus P amended to fields represents a risk to the environment. This study examines the interactions between low-P diets for pigs and dairy cows and the separation of animal slurry into a solid P fraction and a liquid fraction. Replacing inorganic phosphates with phytase in pig feed reduced the concentration of P in slurry by 35%, but supplementing concentrates to dairy cows did not affect the P concentration in cattle slurry. Particle-size fractions of the slurry were not affected by these dietary changes. The amount of dry matter (DM) in the < 0.025 mm fraction was greater in pig slurry than in cattle slurry, but the relative amounts of P and nitrogen (N) were larger in the > 0.025 mm fraction. Replacing feed phosphate, in the form of mono-calcium phosphate, with phytase in the pig diet reduced the separation index (efficiency) of P from 80% to 60%.
Sommer
S G
SG
University of Southern Denmark, Faculty of Engineering, Institute of Chemical Engineering, Biotechnology and Environmental Engineering, Campusvej 55, 5230 Odense M, Denmark.
Maahn
M
M
Poulsen
H D
HD
Hjorth
M
M
Sehested
J
J
D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D005243:Feces / Q000737:chemistry*; D005427:Flocculation; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism*; D012037:Refuse Disposal / Q000379:methods; D013552:Swine / Q000378:metabolism*
D010758:Phosphorus; D009584:Nitrogen