title: Ruminal and total tract phosphorus release from feedstuffs in cattle measured using the mobile nylon bag technique.
abstract: Phosphorus (P) excretion in manure is a concern for dairy and beef producers. Excess P released into surface water runoff can lead to eutrophication and algal blooms in streams and lakes. One approach to reducing P excretion is to reduce dietary P. Data regarding P release from feedstuffs is limited and more precise formulations based on specific feed P release in the digestive tract may be one way to lower excreted P. In this experiment, the mobile nylon bag technique was used to determine the disappearance of P in corn silage, alfalfa hay, Coastal bermudagrass hay, and Tifton-85 bermudagrass hay in steers after ruminal (24 h), ruminal + pepsin/HCl (rumen + PHCl), and ruminal + pepsin/HCl + intestinal (rumen + PHCl + I) incubation. Ruminal disappearance of P differed (p < 0.05) between feedstuffs and by site of incubation. Total tract (rumen + PHCl + I) P disappearance for corn silage, alfalfa hay, Coastal bermudagrass hay, and Tifton-85 bermudagrass hay were 90.6%, 93.7%, 83.8% and 84.0% respectively. The range in P release (approximately 7%) indicates that considering P availability when balancing rations could have a measurable impact on subsequent P excretion from ruminants. More data concerning P availability as affected by other feed ingredients or plant species, maturity, and/or quality are needed to more accurately define P release from ruminant feeds.
authors.affiliation: Texas AgriLife Research, Stephenville, TX, USA.
authors.forename: N M
authors.initials: NM
authors.lastname: Cherry
authors.forename: B D
authors.initials: BD
authors.lastname: Lambert
authors.forename: J P
authors.initials: JP
authors.lastname: Muir
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D007887:Fabaceae; D041981:Gastrointestinal Tract / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D016226:Phosphorus, Dietary / Q000378:metabolism*; D006109:Poaceae; D012417:Rumen / Q000378:metabolism*; D012820:Silage; D003313:Zea mays
chemical_list: D016226:Phosphorus, Dietary; D010758:Phosphorus